WO2014106799A2 - Bis-glycidyl methacrylate monomers for composite resin formulations for dental use, methods for preparing said monomers, resin formulations for direct dental restoration comprising the same and uses thereof - Google Patents

Abstract

A Bis-glycidyl methacrylate monomer of formula (I) wherein R can be a biphenyl group unsubstituted or substituted by OH, oxygen, amino, or Cl- C4 alkyl; a phenyl group unsubstituted or substituted by OH, oxygen, amino, Cl-3 alkyl; a C2-10 alkyl group unsubstituted or substituted by OH, oxygen, amino, Cl- C4 alkyl; a C2-C10 alkenyl group unsubstituted or substituted by hydroxyl, amino, oxygen, C1-C4 alkyl; Also provided are methods for preparation thereof and uses for the formulation of direct resins for dental restoration, as a solvent and as additives improving the properties of the resin.

Description

 BIS-GLICIDILMETACRI MONOMERS FOR THE FORMULATION OF COMPOSITE RESINS FOR DENTAL USE, METHOD FOR THE PREPARATION OF SUCH BIS-GLICIDILMETACRI MONOMETERS FORMS, FORMULATION OF DIRECT DENTAL RESTORATION RESINES THAT I UNDERTAKE AND MON

TECHNICAL FIELD OF THE INVENTION

The present invention relates to new monomers with improved properties for obtaining composite resins of direct dental restoration, processes for their preparation and dental resin formulations containing said monomers.

BACKGROUND OF THE INVENTION

Composite resins are materials that are used in a wide variety of dental applications and comprise a combination of several bimetacrylic monomers, fillers and a photoinitiator system. Thanks to the continuous development in Materials Science, composite materials have significantly improved their physical, mechanical and biocompatibility properties. Despite these advances, composite resins nowadays have limitations in their clinical application; Problems such as discoloration, abrasion and polymerization shrinkage still persist. The main advances made in its formulation, focus on the continuous development of new inorganic filler materials, leaving the organic matrix virtually unchanged. One of the alternatives available to be able to counteract the problems presented by composite resins, is to replace the monomers that form the organic matrix with others of different structures that, due to their characteristics, represent some advantage compared to the monomers currently used . Dental restoration materials currently used

i they have an organic matrix composed, in large proportion, of bisphenolglycidyl methacrylate (Bis-GMA).

Bis-GMA is a monomer of high molecular weight and therefore has a low post-polymerization contraction, however viscosity is a factor that prevents proper handling in the clinic, so it is diluted with other monomers of lower weight Molecular such as trielylene glycol dimethacrylate (TEGDMA) or urethane dimethacrylate (UDGMA) (known as diluents), however this causes the shrinkage of the material to polymerize greatly. Polymerization contraction is still an important cause of clinical failure of restorations. Due to the decrease in volume, an interstitium is formed between the wall of the cavity and the filling material. This gap is easily accessible to bacteria, which can initiate biodegradation processes, and consequently, the worsening of the marginal adaptation of a compound.

Bis-GMA, TEGDMA and UDMA monomers

As mentioned earlier, Bis-GMA finds wide use in today's commercial dental resin compounds although this monomer is too viscous for use without dilution, and cannot be purified by distillation or crystallization. To solve this problem, TEGDMA and UDMA are used commercially, mainly. However, in recent research, various aromatic diesters have been used experimentally, among which we can mention bis (2- methacryloxyethyl) ester of phthalic acid (MEP), and isophthalic acid (MEI) and terephthalic acid (MET), which have the ability to form ternary eutectic, which is a liquid at room temperature, and whose viscosity is suitable for use in resins of dental use.

Structure of aromatic diesters

 Also in the prior art, tests with modified derivatives of Bis-GMA have been described by changing the hydroxy group to alkoxy groups (methoxy, propoxy, butoxy) in combination with spiro orthocarbonates, obtaining materials with reduced contractions and better mechanical strength.

On the other hand, Dupont developed a urethane dimethacrylic resin, DX-510, whose molecular weight (PM 895) doubles that of Bis-GMA or UDMA, and whose structure has a rigid and flexible part where the polymerizable groups are located. This monomer shows a reduction in polymerization shrinkage because it has a lower number of carbon-carbon double bonds per unit mass.

Other monomers that have been recently patented are the CD-di-HEMA and the TCD-di-HEA, which contain a rigid part (containing the tricycle [5.2.10] ^2.10 dean) and side chains of Optimized size, to improve elasticity, reduce shrinkage tension and decrease marginal filtration.

Tricycle structure [5.2.10]

Also mentioned is Japanese patent JP5320020 (a) entitled "Denture-base resin composition and artificial tooth" which discloses a resin composition comprising a monofunctional (A) monomer (where Rl is acryloyl, methacryloyl, maleoyl, fumaroyl, itaconoyl, vinyl , vinylbenzyl or allyl; R2 is H, C1-C8 is alkyl, C3-C8 is cycloalkyl or phenyl; R3 is H or methyl; n is 1 to 50) according to formula I, and a bifunctional (B) monomer of formula II ( R4 and R5 are Rl; R6 is R3), for example ethyloxy dimethacrylate among other components.

(R ¹ ) - (OCH ₂ CH (R ³ ) H) _n -OR ² (I) (R ⁴ ) - (OCH ₂ CH (R ⁶ ) H) _n -OR ⁵ (II)

For its part, US4001483 (A) discloses a composition for use as a dental sealant comprising an a. alkylene glycol dimethacrylate of formula:

CH ₂ = C (CH ₃ ) COO (CH ₂ CH ₂ 0) _n COC (CH ₃ ) = CH ₂ where n is an integer from 2 to 4, b. a polymerization initiator; C. a polymerization accelerator, and d. a secondary monomer additive selected from the group consisting of glycidyl methacrylate and tetra h id rofurfu rile, in a concentration of about twenty percent to about seventy percent based on the total weight of the composition, components (b) and (c) they are present in smaller effective amounts and the rest of the composition is essentially dimethacrylate.

US patent 5865623 entitled "Flexible dental composite compositions and restorative methods using fexible dental composition", discloses compositions of flexible dental composites comprising (a) between 2 and 15 per weight percent of a portion of flexible monomer comprising one or more flexible co-monomers of general formula

R ¹ -0 - [(CH-R ² ) _n -0-] _z -R ³ where R ¹ and R ³ are acrylate or methacrylate functional groups, R ² is selected from the group consisting of hydrogen, methyl, and ethyl, n is 3 or 5 and z is 3 to 20 and the monomer has an average molecular weight of at least 300, (b) between 30 and 80 percent by weight of a filler portion, c) from 18 to 60 percent by weight of a co-monomer comprising one or more co-monomers capable of polymerizing with the flexible monomer portion and (d) a polymerization catalyst system. The composition is useful for dental restorations of class V and other classes.

JP59070645 (A) discloses a monomer having the following structure 4,4-'bis- (2-hydroxy-3-methacryloxyxypropyloxy) biphenyl ether.

Structure of 4,4 -'- bis- (2-hydroxy-3-methacryloxypropyloxy) biphenyl ether

This monomer is used as a reinforcing adhesive agent to improve the adhesiveness of adhesives especially used for dental therapy. Also, a process is disclosed comprising the preparation of an alpha, beta-unsaturated monocarboxylic acid ester by reaction of glycidyl methacrylate with 4,4'-dihydroxyphenyl ether in the presence of a catalyst (for example a quaternary ammonium salt) or by reacting 4,4'-dihydroxybiphenyl ether with epichlorohydrin in the presence of a base, and reacting the resulting 4,4'-diglycidyloxybiphenyl ether with methacrylic acid in the presence of a catalyst (for example a quaternary ammonium salt). Therefore, there is a need in the prior art to provide new monomers that exhibit a suitable combination of physical, mechanical and biocompatibility properties for the preparation of composites useful in dental applications.

The present invention aims to provide new monomers that allow to obtain resins that exhibit improved material handling properties and the mechanical, optical and biocompatibility properties of dental resins.

The present invention aims to provide new monomers, which make it possible to obtain resins that exhibit an increase in mechanical properties without adversely altering the optical, handling and biocompatibility characteristics of dental resins.

Specifically, the present invention aims at the preparation of dental resins based on a new organic matrix from new bis-glycidyl methacrylate monomers that can be used as solvents and as additives that improve the properties of the resin, and which by their characteristics bifunctional, could also be used in other polymerization reactions as bifunctional crosslinking agents, giving rise to various applications.

The inclusion of these monomers in other vinyl polymerizations would produce an increase in average molecular weights, which would lead to more viscous materials or to produce more viscous solutions. Taking into account the structures of these new compounds could be used to modify the properties of other acrylic polymers, such as hardness, abrasion resistance, viscosity, use temperatures, etc.

BRIEF DESCRIPTION OF THE FIGURES

Figure 1 Infrared spectrum of compound BE-4,4-0H Figure 2 H NMR spectrum of compound BE-4,4-0H

Figure 3 ¹³ C NMR spectrum of compound BE-4,4-0H

Figure 4 Comparison of the FT-IR spectra for the raw material, intermediate compound and bifunctional monomer from 4,4-biphenol.

Figure 5 NMR spectrum ¹ of compound MB-4,4-OH

Figure 6 ¹³ C NMR spectrum of compound MB-4.4-0H

Figure 7 Infrared spectrum of the BE-Fen-OH compound

Figure 8 NMR spectrum ¹ of the BE-Fen-OH compound

Figure 9 ¹³ C NMR spectrum of the BE-Fen-OH compound

Figure 10 Infrared spectrum of compound MB-Fen-OH

Figure 11 NMR spectrum ¹ of compound MB-Fen-OH

Figure 12 ¹³ C NMR spectrum of the MB-Fen-OH compound

Figure 13 Comparison of NMR ¹ spectra for the raw material, intermediate compound and bifunctional monomer from 1,4-benzenedimethanol.

Figure 14 Infrared spectrum of compound BE-1,4-0H Figure 15 NMR spectrum ¹ of compound BE-1,4-0H Figure 2 NMR spectrum ¹³ C of compound BE-1,4-0H Figure 17 Infrared spectrum of compound MB-1.4-0H Figure 18 NMR spectrum H of compound MB- 1.4-0H Figure 19 NMR spectrum 13C of compound MB-1.4-0H Figure 20 Infrared spectrum of compound BE-Cis-OH Figure 21 NMR spectrum ¹ of compound BE-Cis-OH Figure 22 ¹³ C NMR spectrum of the BE-Cis-OH compound

Figure 23 Infrared spectrum of compound MB-Cis-OH

Figure 24 1H NMR spectrum of MB-Cis-OH compound

Figure 25 ¹³ C NMR spectrum of MB-Cis-OH compound

Figure 26 Infrared spectrum of compound BE-l, 7-OH

Figure 27 * H NMR spectrum of compound BE-l, 7-OH

Figure 28 ¹³ C NMR spectrum of compound BE-l, 7-OH

Figure 29 Infrared spectrum of compound MB-l, 7-OH

Figure 30 * H NMR spectrum of compound MB-l, 7-OH

Figure 31 ¹³ C NMR spectrum of compound MB-l, 7-OH

DETAILED DESCRIPTION OF THE INVENTION

The properties of a composite material are given based on the properties of the phases that constitute it, the relative amount of each of them, as well as the geometry of the dispersed phase, such as its shape and size, as well as its distribution and orientation (9, 15-17, 19).

The matrix in a composite material comprises between 30 and 40% of its structure, and has numerous functions (17):

• Joins the components and determines the thermo-mechanical stability of the composite material.

 • Protects the reinforcement material from wear and abrasion, as well as the environment.

 • Helps distribute loads acting as a means of transferring stresses.

• Provides durability and mechanical resistance to the system in general. The role played by the organic matrix within the final properties of the composite material is much more important than that of the dispersed or reinforcement phase (15). One of the characteristics that reinforcements have is that they have a very high elastic modulus, and therefore they are very fragile solids that, in the presence of a load, fracture easily; the combination with a matrix of different nature and characteristics will result in a material with the characteristic of bearing greater loads without presenting immediate fracture (17).

The matrix of a composite material can be composed of ceramic materials, metals or polymers, in this way we have composite materials of ceramic matrix, metal matrix or polymer matrix (15).

The dispersed phase of the composite materials is constituted by a reinforcement material, which can be discontinuous (particles, scales, short fibers) or continuous (fibers or long sheets) (17, 19). Usually, fiber-like reinforcement materials are stronger and harder than any other type of filler, and this is the main reason why most composite materials contain fillers with this geometry (15, 16).

The reinforcement material is also stronger, harder and more rigid than the matrix and its size, shape, concentration and distribution within the composite material, represents one of the greatest parameters to determine its effectiveness (18, 20).

The size of the filler particles can vary in the order of the microns to the nanometers, their shape can vary and present in the form of fibers or cubic or spherical particles, in the same way, the arrangement can range from being completely random, to having a certain orientation, and the mechanical properties of the composite material will vary according to these characteristics (15, 17, 19).

Such is the case of acrylic resins, in which the incorporation of vitreous inorganic fillers, affects properties such as the coefficient of expansion thermal, polymerization contraction and hardness, almost linearly with respect to the percentage of filler included (11).

In general, composite materials are classified according to the type of material that is conforming to the matrix (15, 17).

In metal matrix composite materials (MCM), the use of metals to form the matrix is mainly due to the following reasons: they have applications in a wide range of temperatures, in general they have higher hardness values, the effect of moisture and the danger of flammability is absent, they have high thermal and electrical conductivity and also, compared to pure metals or alloys, they have greater resistance to fatigue and abrasion, as well as lower coefficient of thermal expansion (9, 16, 17).

Similarly, the use of metals within a composite material represents certain disadvantages (19). Among these, we can mention that the materials turn out to be very heavy and are susceptible to corrosion (17).

Composite materials with ceramic matrix (MCC) can be composed of metallic or non-metallic elements. Among the characteristics that ceramic materials possess and that make them useful for the production of composite materials, are: they have a very large application range, have very low densities and also have a very high elastic modulus (15, 17 , 19).

The greatest disadvantage of this type of materials is its fragility, which makes them very susceptible to structural defects (17).

Polymeric matrix (MCP) materials can be considered as the most developed composite materials, in addition to finding a wide variety of applications (19). In addition, the CCMs can be manufactured very easily (17).

CCMs result from a synergistic combination between a high performance filler and a polymeric organic matrix. In these types of systems, the reinforcement provides better mechanical properties to the material, while the organic matrix distributes the loads and increases resistance to wear and corrosion. Thus, in MCPs, the mechanical properties are directly proportional to the properties of the reinforcement material (9, 15, 16, 19).

The limitations of this type of materials also come from the type of polymer matrix being used (15, 17, 19). To cite an example, if thermoplastic polymers are used, then the composite material would have a very limited application temperature range (17).

Structurally speaking, a composite resin for dental use is a crosslinked polymeric material reinforced with dispersed filler particles bonded to the polymer matrix by means of silane type coupling agents (7).

According to the classification addressed above, materials of this type correspond to a polymer matrix composite material with a particulate reinforcement. In Dentistry, the term composite resin refers to a reinforced polymeric system used for the restoration of hard dental tissues, such as enamel and dentin (6).

Composite resins are used to replace lost dental structures, and one of the advantages of this material is the versatility for its application, whether in areas where aesthetics has been compromised, such as in areas subject to many forces, such materials they can be used with good results (21). In addition to these, composite resins are used in a variety of other applications, such as pit and fissure senators, cemented ceramic restorations and other types of fixed restorations (7).

Composite resins for dental use were developed in the early sixties (21-24). The first restorative materials of this type were self-healing; for the next generation, they were photoactivated materials with ultraviolet light. These were then replaced by materials activated by visible light. The following improvements made, have contributed to achieve a composite resin with excellent durability, abrasion resistance and aesthetics that allows to perfectly mimic natural teeth (7, 11, 12).

Resins

A composite resin consists of four main components: polymeric matrix or organic matrix, inorganic filler particles, coupling agent and an initiator-accelerator system (6, 7, 22). All properties and performance of these types of materials depend on the nature of these components; some are broadly related to the filler and the binding agent, while others depend solely on the organic matrix (25).

One of the main benefits of using the polymer matrix is the ability that the material can be molded at room temperature, together with the possibility of doing so in a considerably short time. The benefits provided by the inorganic filler are increased stiffness, hardness and strength, as well as a low thermal expansion coefficient (11).

The majority of composite resins for dental use commercially available today use a mixture of aromatic and aliphatic monomers as components of their organic matrix (5, 7, 11, 21, 22, 26).

The main monomers used for this purpose are listed below:

• Bis-GMA

• TEGDMA

 • UDMA

 • BÍS-EMA6

 • Bis-EMA

• PEGMA Filtek Supreme XT 3M resin contains bis-GMA, UDMA, TEGDMA, BISEN! A, PEGDMA

bis-EMA2,2-bis (4- (2-methacryloxyethoxy) phenylpropane

PEGMA

Structure of bis-EMA2,2-bis (4- (2- methacryloxyethoxy) phenylpropane and PEGMA monomers

Two of the most commonly used monomers for this purpose are glycidyl bisphenol A-methacrylate (Bis-GMA) and urethane dimethacrylate (UDMA). Both monomers have carbon-carbon double bonds at each end of the molecule and can easily polymerize by free radicals (6, 7). In said molecules, each of the double bonds forms part of the polymerization by addition, which gives it the possibility of forming crosslinked networks (11).

The viscosity of these monomers, especially Bis-GMA, is very high, so formulating a resin with a suitable clinical consistency as well as to be able to incorporate the greatest amount of inorganic filler, other bifunctional low molecular weight monomers are used, such as triethylene glycol dimethacrylate (TEGDMA) or Bis-EMA6 (12). The structure of these monomers is shown below.

 Structure n n-6m-eFci BSs-E3 "íSAó

Structure of the Bis-GMA, UDMA, TEGDMA and Bis-EMA6 monomers

The use of bimetacrylic monomers has the advantage of producing polymer chains with a high degree of crosslinking. The result is a rigid matrix highly resistant to softening and / or degradation by heat or solvents such as water or alcohol (7).

Stuffed

Additionally, composite materials include inorganic fillers in order to improve their physicochemical and mechanical properties.

The inorganic filler forms most of the volume or weight of a composite material, depending on the type of resin, the total amount of inorganic filler material incorporated into commercial composite resins ranges between 42 and 85%. The incorporation of the filler particles into an organic matrix significantly improves the mechanical properties of the material (5, 11). Among the properties of a composite resin, which the inorganic filler can improve, are (7):

• Increase of hardness and resistance.

 • Abrasion reduction.

 • Reduction of polymerization shrinkage and thermal expansion.

• Ease of handling by increasing viscosity.

 • Reduction of solubility and aqueous sorption.

 • Increase in radiopacity.

The filler particles most frequently used in the manufacture of these composite materials are produced by grinding, crushing or pulverizing minerals such as quartz, barium glass, barium glass / silica, barium glass, quartz / barium glass, silica, zirconia / silica, mixture of silica, lithium aluminosilicate, sodium silicate and / or zinc alumino and barium aluminosilicate or sol-gel derivatives of ceramic materials, which produces particles with a size in the range of 0.1 to 100 μπι (7, 11). Recently, particles of nanometric size of silica have been incorporated into materials of this type (11, 22).

Many of the glasses used as inorganic fillers have heavy metal oxides such as barium or zinc, which provides radiopacity to be visualized when exposed to X-rays (6).

During the initial development of the composite resins, Bowen showed that the optimum properties of the material depended on the formation of a strong bond between the inorganic filler and the organic matrix, if this did not happen, the filler particles do not act as reinforcement, but as material debilitators (7).

The surface of these fillers is usually treated with a coupling agent that can be used in amounts ranging from 40 to 95% by weight based on the total weight of the composition.

Coupling agents The union of the inorganic phase with the organic phase is achieved by coating the filler particles with a coupling agent having both filler and matrix characteristics. The agent responsible for this binding is a bifunctional molecule called silane (22).

Silanes, are a group of organic compounds that have the particularity of reacting with organic and inorganic substrates, as well as with themselves and with other silanes, this is achieved through complex hydrolysis and condensation reactions to form a wide variety of hybrid structures organic and inorganic (27).

In methacrylate-based resins, the binding agent between the organic matrix and the filler particles is 3-methacryloxypropyl trimethoxy silane (MPTMS), which is a bifunctional molecule capable of reacting with itself, with the agent filling and methacrylate groups. The amount of reactions that occur between these groups will determine the effectiveness of the coupling agent (6). The structure of the MPTMS is illustrated below:

MPTMS structure

The silanization of a filler material can be seen in the figure below. In the presence of water, the methoxy groups (-0-CH ₃ ) are hydrolyzed and converted to silanol (Si-OH) groups, which can bind to other silanol groups located on the surface of the filler particles and form covalent bonds called siloxanes (-Si-O-Si-) (7).

Silanization of inorganic filler

 According to the previous image, it is possible to observe that the methacrylate group of the silane molecule is free to form covalent bonds, once it polymerizes, with other methacrylates from the resinous matrix, thus completing the coupling process (22) .

The silane improves the physical and mechanical properties of the composite resin, as it establishes a stress transfer of the easily deformed phase (resinous matrix), for the more rigid phase (filler particles). In addition, these coupling agents prevent the penetration of water into the BisGMA / filler particles interface, promoting hydrolytic stability inside the resin. Representative examples are 3- methacryloxypropyl trimethoxy silane (MPTMS), vinyl triethoxysilane, dimethyl dichlorosilane, hexamethylene disilazane, dimethyl polysiloxane among others.

Other agents such as 4-META, various titanates and zirconates have been experienced, however, none of these agents proved to be superior to MPS (22).

Photoinitiator system Hardening of materials of this type is carried out by addition polymerization initiated by free radicals. These free radicals can be generated through a chemical reaction or through external energy in the form of light (6, 7, 11). The activation by light is carried out by exposing the material to blue light with a wavelength of 465 nm, said light is absorbed by a photosensitive molecule, such as canforquinone, which generates the free radicals that initiate the process of polymerization The reaction is accelerated by the presence of an organic amine, such as ethyl 2-N, N'-dimethylaminomethacrylate, N, N ^' -dimethyl-para-toluidine and ethyl ρ-Ν, Ν ^' - dimethylaminobenzoate. The total amount of activator and accelerator that is added to a commercial formulation of a composite resin varies between 0.1 and 1% by weight of each of them, based on the total weight of the composite resin composition. (7).

For its part, chemical activation is carried out when an organic amine reacts with a peroxide to form free radicals, which in turn attack the carbon-carbon double bonds and cause the polymerization process (5). In this type of materials, the commercial presentation always comes under two separate components, one of them contains the organic amine while the other has the peroxide group, once they are mixed, the polymerization process occurs immediately (6, 11).

Other additives that can be added to the resin may be polymerization inhibitors, photostabilizing agents, antioxidant agents, and pigments to form the color of the composite resin. A polymerization inhibitor such as hydroquinone (HQ), hydroquinone monomethyl ether or hydroquinone monoethyl ether can be added in an amount of 0.1 to 10% by weight based on the total weight of the composition. A photostabilizer such as Tinubin can be added in an amount of 0.01 to 5% by weight based on the total weight of the composition. An antioxidant such as Irganox (Tetrakis Propionate (3- (3,5-di-tert-butyl-4-hydroxyphenyl) pentaerythritol) and 2,6-di-tert-butyl-4-methyl phenol, butylhydroxytoluene (BHT) can be added in an amount of 0.01 to 5% by weight based on the total weight of the composition: Inorganic pigments yellow, navy blue, or red-iron oxides and iron dioxide Titanium can be added in an amount of% by weight of from 0.005 to 0.5 based on the total weight of the composition.

Some recently introduced composite resins are dual curing, that is, they polymerize by chemical reaction as well as by exposure to visible light. The formulation in this type of products contains initiators and accelerators that allow the generation of free radicals by the two routes described above (6).

Resin Classification

Composite resins for dental use are classified using as a main criterion the average size of particles that are forming in the inorganic matrix thereof (28-30). According to Table 1, several groups of dental composite resins can be distinguished, each with different clinical applications (6, 7).

Table 1 Classification of Composite Resins

 Type of Clinical Uses Size

 Particle Material

Traditional 1-50 μπι High stress areas

Hybrids (1) 1-10 μπι High stress areas a

 where good is required

(2) 0.04-0.2 μπι

 polished.

Microhybrid (1) 0.1-2 μπι High stress areas a

 where good is required

(2) 0.04-0.1 μπι

 polished.

Nanofill 1-100 nm High stress areas at

where good polishing is required. Nanohybrid (1) 0.4 μηι High stress areas a

 where good is required

(2) 1-100 mm

 polished.

Traditional Resins: This type of resins corresponds to one of the oldest products of this type, which is why they receive that name. They use quartz particles or strontium or barium crystals whose size varies between 10 and 50 micrometers (31).

Although these types of resins have acceptable mechanical properties, their clinical use has fallen into disuse. Due to the large dimensions of the charge particles, these types of resins are difficult to polish, in addition to the fact that the detachment of some filler particle causes the formation of small craters. This results in the possibility of trapping various compounds, causing significant pigmentation of the material (7).

Hybrid and microhybrid composite resins; This classification includes materials in whose composition there are two different sizes of inorganic filler particles. The combination of sizes confers unique properties to the materials, since it improves the transfer of tensions between the particles in the composite, thereby increasing the resistance of the resin

(7).

The aspects that characterize these materials are: to have a great variety of colors and ability to mimic the dental structure, less polymerization contraction, low aqueous sorption, excellent polishing and texturing characteristics; abrasion, wear and coefficient of thermal expansion very similar to that of dental structures, formulas for universal use in both the anterior and posterior sectors and different degrees of opacity and translucency in different shades and fluorescence (30).

Nanofill Resins: These contain filler particles between 1 and 100 nm in size along the organic matrix (29, 30). One of the main reasons why particles of such a small scale are incorporated is because their size is below the scale of visible light (400-800 nm), which makes it possible to create materials with high translucency (6 ).

There are two different types of nanoparticles that are added to dental composite resins. The first one is based on monodispersed non-aggregated particles of silica or zirconia, while a second type consists of a controlled size aggregate of these nanoparticles known as nanocluster (24).

In nanoclusters, the particles maintain their original shape and size, and these agglomerate in such a way that they allow to make particles larger than 0.6 microns in size (24).

Nanofill materials can be considered unique, since they have quite acceptable mechanical properties, while presenting excellent optical properties and that over time they are preserved (6).

In summary, the nanofills used in commercial formulations are:

• Silicon oxide

• Zirconium Oxide

As previously mentioned, nanometric particles offer this type of materials the possibility of showing translucency; This feature allows resins to be created with a wide variety of colors and opacities that allow restorations that match the appearance of dental tissues (11).

For chemically activated materials, polymerization begins immediately after mixing of the two components of the material. The degree of polymerization is uniform throughout the entire material, causing a gradual increase in its viscosity (5, 11). For the above the Working time for this group of materials is limited, from 3 to 5 minutes (6).

In the case of light activated materials, polymerization begins only when the material is exposed to light and hardens seconds after this occurs. Although the material has a hard and completely polymerized appearance, it is important to mention that the reaction continues for a period of 24 hours (7). What happens is that not all available double bonds polymerize, in fact, 25% of these remain unreacted within the restoration (24), in addition, a small layer of oxygen-inhibited material remains unpolymerized on the surface of the resin, which is beneficial to be able to apply the technique of ncremental placement in these restorative systems (7).

The time and depth of polymerization of the materials activated by light, depend to a greater extent on the intensity of the lamp as well as the amount of penetration of the beam into the material (5). It is also important to consider that exposure to ambient light for between 60 and 90 seconds, makes the surface of the composite material lose its ability to flow and therefore, its handling becomes difficult (6).

Polymerization shrinkage is the major drawback of these restoration materials and, to this day, all resins suffer from contraction with different values depending on the type to which they belong (32-34).

The polymerization shrinkage values of some current restorative systems may present a final reduction in volume from 0.5% to 3% according to recent publications (21, 24, 32, 35-38).

When the resin has not yet activated its initiator systems, the matrix molecules of a composite resin are separated by an average distance of 0.340 nm, this distance is given by the forces of Van der Waals exerted by the elements that make up each monomer; by polymerizing and establishing covalent bonds with each other, that distance is reduced to 0.154 nm. At the end and together, the polymerized material is more compact and with a smaller volume compared to the same material when it has not polymerized (22, 39).

If we are located within a composite resin restoration, the polymerization contraction causes residual stress, that is, when the polymerization resins produce and accumulate stress that remains within the restoration without being able to dissipate completely (40, 41). To this we must add that if the adhesion of the resin to the cavity walls restricts the volumetric changes, the stress is then transferred directly to the tooth. In bismetacrylates, about 80% of polymerization contraction results in the formation of stress within the tooth structure (23).

The volumetric contraction produces a contraction stress of around 13 MPa, enough to severely deform the resin-tooth interface, causing gaps that can cause the appearance of marginal caries, likewise, stress can overcome the tensile strength of the enamel and cause fractures (37).

Another property that should be considered in the design of dental composites is the coefficient of thermal expansion. The coefficient of thermal expansion is the rate of dimensional change per unit of temperature change. The closer the coefficient of thermal expansion of the resin is close to the coefficient of thermal expansion of dental tissues, the less likely there will be marginal gaps between the tooth and the restoration, as the temperature changes (22).

The coefficient of linear thermal expansion for composite resins ranges from 25 to 68xlO ^"6 / ° C. This value is higher than the values established for enamel (Il, 4xl0 ^{" 6} / ° C) and for dentin 8.3xlO ^"6 / ° C) (11).

The difference in the values for this property can lead to additional stress at the resin-tooth interface, which can lead to the appearance of gaps in the restoration and allow the percolation of oral fluids (6). The polymer matrix of a composite resin for dental use is capable of absorbing water, a phenomenon related to the reduction of surface hardness and wear resistance of the material (11).

The incorporation of water in the resin, can cause solubility of the matrix negatively affecting the properties of the resin, this phenomenon is known as hydrolytic degradation. The quality and stability of the coupling agent is very important to minimize the deterioration of the joint between the filler and the organic matrix and, therefore, the amount of water it can absorb (27).

Aqueous sorption is a property attributed to the organic phase, so the higher the percentage of filler incorporated into the material, the lower it will be. In the case of hybrid composite resins, this value ranges between 5 and 17 μι / mm ³ , and for micro-filling resins it rises to 30 m / mm ³ (6).

The expansion caused by the absorption of water by the material can partially relieve the stress caused by polymerization contraction (42, 43); However, the phenomenon of aqueous sorption is a slow process, and many of the resins require four days to show the greatest possible expansion (6).

The mechanical properties of this type of materials reflect the amount of inorganic filler of which they are composed, the type of filler, the efficiency of the matrix-filler coupling process as well as the porosity of the polymerized material (5, 11). Table 2 presents the main mechanical properties of various composite resins. Table 2 Main mechanical properties of composite resins

Property Resin Resin Enamel Composite composite dentin

 of hybrid

 micro-filled

Resistance to 260 300 384 297

 compression

 (MPa)

Module 6 14 84 18

 Young (GPa)

Stamina 40 50 10 51

 tensile (MPa)

Resistance 80 150 - - Flexural (MPa)

Hardness (VHN) 30 90 408 60

A material with a low elastic modulus deforms in the presence of a load. Compared to enamel, composite resins have only a very small fraction of this value. This represents a problem, since during the masticatory loads, the deformation of the restoration generates stress in the resin-tooth interface (7, 10).

Compressive strength is an important value in this group of materials since, as a result of chewing, it is the main type of force to which they are subjected (6).

Hardness is a property directly related to the amount of inorganic filler and the degree of polymerization (5). The hardness value on the Vickers scale for a resin without inorganic filler is 18, while that for a microhybrid type resin, this value rises to almost 100 (11).

Since its inception, this type of restorative systems has undergone numerous changes in its composition, with improvements in inorganic filler and initiation mechanisms being the main advances that have been achieved (24).

With some exceptions such as Filtek Silorane® (3M ESPE), which is based on a cyclic monomer called silorane; Kalore® (GC América), presents in its organic matrix a high molecular weight bismetacrylic monomer called DX-511; Venus Diamond® (Kulzer), material based on the urethane monomer TCD-DI-HEA; and N'Durance® (Septodont), in whose organic matrix araliphatic or aromatic dimethacrylic monomers and acid dimers of urethane methacrylates are used; The rest of the composite resin-based restorative systems that we can find commercially have as main components the BisGMA / TEGDMA pair (21, 25, 26).

In recent years, the development of new monomers has become a research focus on materials of this type. Recent research allows to demonstrate that the use of alternatives other than Bis-GMA / TEGDMA as a polymer matrix, manages to improve some of the properties of composite resins for dental use, such as flexural strength and flexural modulus, as well as reduce significantly the levels of polymerization contraction (44-52).

The vast majority of the scientific evidence available, leads us to think that the most appropriate way to improve this type of materials is in the synthesis of new monomers that, due to their chemical structure, can improve the properties of the materials of which It is currently available. The new monomers that are designed for this purpose are designed so that they can have some of the following characteristics: reduction of polymerization shrinkage, release of fluoride or some other cariostatic substances, improve mechanical properties and improve biocompatibility by reducing the number of components that are released into the oral environment (14, 23).

According to these characteristics, numerous researchers have designed, synthesized and applied various monomers that meet the above mentioned characteristics. These monomers, according to Vasudeva, can be classified into 4 types (26):

1. Monomer systems with low polymerization shrinkage.

 2. Systems of anticariogenic monomers.

 3. Hydrophobic monomer systems.

 4. Monomer systems of high resistance and high degree of conversion.

Monomer systems with low polymerization shrinkage.

The reduction of the polymerization contraction of the current restorative systems is one of the main challenges to overcome when synthesizing new monomers, since, for the reasons that will be exposed in another section of this work, this characteristic of the restorative systems Current is one of the main factors that determine the longevity of a restoration made with this type of material (32, 38, 53, 54).

The first approach made to achieve this was the use of bicyclic compounds that polymerized by a mechanism called ring opening. Such compounds were reported by Baileys and included a wide variety of monomers that included ortho-spirocarbonates, bicycloacetalactones, trioxabicycloctanes and unsaturated acetals of benzoquinone (23, 55).

The interest in the application of this type of compound in dental resins is derived because they have 30 or 40% less shrinkage than the methacrylates currently used (39). One of the composite resins for dental use that we find in the market is Filtek Silorane® (3M ESPE). Said resin uses, within its composition, an organic matrix based on monomers that polymerize via the opening of rings known as silorans (56).

The main advantage of this new type of compounds is the low polymerization shrinkage. Composite resins based on siloranos have a volumetric contraction ranging from 0.94% to 0.99% according to the method used (48, 57, 58).

Siloranos reveal physical properties comparable to composite resins that are based on methacrylates (59); Also, toxicological studies reveal that silorane-based composites are fully biocompatible (58, 60).

Table 3 describes other monomers of these characteristics that have been synthesized and applied experimentally by various authors. Some of these monomers have a high molecular weight, and others within their structure, have cyclic compounds that open at the time of polymerization. The results of mechanical tests made with composite materials based on these new monomers, reveal that their contraction percentage is significantly lower than that of the BisGMA / TEGDMA pair, while the behavior in terms of its flexural modulus and flexural strength is not visible. significantly affected when compared to a control group. (50, 61-73).

Table 3 Monomers with low polymerization shrinkage

THMPEIB

NA-EG n NA-BG n NA-HG n

TTEMA

Anti-cryogenic monomer systems.

One of the different ideas that emerged to compensate for the adverse effect of polymerization contraction that restorative systems present is to include anti-cryogenic substances that could be released and thus prevent the accumulation of bacterial plaque around a resin-tooth interface impaired (26, 39).

For this purpose, different compounds such as chlorhexidine have been included in experimental materials, observing a certain antibacterial activity caused by the release of this substance; however, the activity is reduced over time as well as Increase the aqueous sorption of these materials, their mechanical properties are reduced over time (74, 75).

In the following scheme you can see different monomers that include in their structure anticariogenic elements that have been synthesized to evaluate their bactericidal properties. These new monomers present mostly the fluorine element within their structure, which gives them the ability to be used as cariostatic agents. In these new monomer systems studied, their ability to release fluoride to the oral environment is sufficient to establish a potential benefit, while the mechanical properties obtained with them are comparable with those of the BisGMA / TEGDMA pair (76-78).

BisFDFA FBBMA

 FBDFA

 BísFGMÁ

 FBGMA

Hydrophobic monomer systems. Aqueous sorption is a phenomenon related to the reduction of surface hardness and wear resistance of the material (11), which is why one of the attempts made to reduce this characteristic in matrix composite materials Polymeric is to achieve monomer systems that do not have the capacity to form secondary joints with water (39).

Modifications in this regard have been reduced in changing some of the structures of the BisGMA monomer. Many of these modifications focus on replacing the pending hydroxyl groups and the methyl groups present in the center of the molecule chain with other atoms of different nature (14).

An example of this is the study by Sankaparandian, who studied the aqueous sorption and hardness of several monomers analogous to BisGMA, where the central methyl groups were replaced by fluorine and aromatic rings. This study allowed to demonstrate that those fluorinated monomers were found to have 10% less aqueous sorption with respect to BisGMA (51).

Monomer systems of high resistance and high degree of conversion.

The mechanical properties of the polymers depend largely on their degree of polymerization and molecular weight, as well as the number of branches and the degree of crosslinking that it presents (2).

Currently, the degree of conversion for the BisGMA / TEGDMA system ranges from 42 to 85% depending on the type of study (33, 41, 79-81). It has been shown that the presence of residual monomer impairs the chemical, physical and mechanical properties of these materials, so new monomers with a better degree of conversion have been proposed (26).

It is known that the increase of the TEGDMA monomer in the formulation of a composite resin improves the degree of conversion of the materials, without However, as the concentration of this linear monomer increases, the mechanical properties decrease (82, 83).

Based on this, several investigations focus on the substitution of the TEGDMA monomer as a diluent of BisGMA, with others whose structure allows to increase the degree of conversion, at the same time that does not harm the mechanical properties of the resulting materials (63, 82, 84 , 85).

Although composite resins are formed by the three-dimensional combination of chemically different materials from each other, it is possible to consider, within this group of components, the organic matrix and the backbone of this type of restorative system (22), and therefore, to attribute to it, the great majority of the inconveniences that these restorative materials present.

The organic matrix of current restorative systems is made up of the Bis-GMA / TEGDMA pair. One of the great disadvantages of these monomers is their degree of incomplete conversion, which results in the formation of less resistant polymers; In addition, its high viscosity prevents the addition of a higher percentage of inorganic filler, reducing its resistance (50).

Polymerization shrinkage is another problem derived from the organic matrix; Factors such as the molecular weight and the degree of crosslinking of the monomers, as well as the amount of inorganic filler contained in the composite material, determine the percentage of contraction of the material (23, 24, 32).

In recent years, this type of materials has undergone numerous experimental modifications, and one of the alternatives that has been presented to counteract these types of problems, focuses on the replacement of the organic matrix, with one that contains new monomers that due to their chemical characteristics, may result in materials with better properties (23).

With the growing demand for increasingly functional and aesthetic restorations, researchers and manufacturers have focused on the development of new technologies that make composite resin an ideal restoration material. The development of new monomers that manage to improve some characteristic of the current composite resin systems, is considered as one of the alternatives that could improve the characteristics and properties of materials of this type.

Therefore, the present invention aims to provide new monomers that allow to obtain an advantageous mechanical performance of materials based on them overcoming the problems of the prior art. The improvements introduced in the properties of resin-based composite materials will allow a step forward in the search for new and better materials that can be used in a greater number of clinical applications with good long-term results.

Therefore, the present invention provides novel monomers that have the general formula (I):

where R can be

a biphenyl group unsubstituted or substituted by OH, oxygen, ermine, or C1-C4 alkyl, carbonyl or carboxyl; a phenyl group unsubstituted or substituted by OH, oxygen, amino, Cl-4 alkyl, carbonyl or carboxyl;

a C2-10 alkyl group unsubstituted or substituted by OH, oxygen, amino, C1-C4 alkyl, carbonyl or carboxyl;

a C2-C10 alkenyl group unsubstituted or substituted by hydroxyl, amino, oxygen, C1-C4 alkyl, carbonyl or carboxyl;

Preferred monomers are those where R has the following meanings:

Obtaining the following monomers:

 -Cis-OH

 B-1.7-OH

Another object of the invention relates to methods for the preparation of said bis-glycidyl methacrylate monomers.

The general method for obtaining the monomer of the general formula (I)

where R can be

a biphenyl group unsubstituted or substituted by OH, oxygen, amino, or C1-C4 alkyl, carbonyl or carboxyl; a phenyl group unsubstituted or substituted by OH, oxygen, amino, Cl-4 alkyl, carbonyl or carboxyl; a C2-10 alkyl group unsubstituted or substituted by OH, oxygen, ermine, C1-C4 alkyl, carbonyl or carboxyl; a C2-C10 alkenyl group unsubstituted or substituted by hydroxyl, ermine, oxygen, C1-C4 alkylcarbonyl or carboxyl, comprises the steps of: a) reacting a compound of the general formula OH-R-OH with epichlorohydrin to give an intermediate compound in the presence of a solvent and b) reacting the intermediate compound obtained from step a) with methacrylic acid in the presence of a solvent and a catalyst to give the compound of general formula (I) according to the following reaction scheme:

where R has the meanings defined above.

In a preferred embodiment of the present invention, the monomer

4,4'-bis [2-hydroxy-3-methacryloxypropoxy] biphenyl is obtained according to a general procedure comprising the steps of: a) reacting a compound of 4.4 bisphenol with epichlorohydrin in the presence of a solvent to obtain the intermediate compound of formula BE-4,4-0H

Y

b) reacting the intermediate compound with methacrylic acid in the presence of a solvent to obtain the compound 4,4'-bis [2-hydroxy-3-methacryloxypropoxy] biphenyl of formula MB-4,4-0H:

Preferably in steps a) of the method of obtaining the MB-4,4-0H monomer, a 4.4 bisphenol compound is reacted with epichlorohydrin in the presence of dimethylformamide as solvent and potassium carbonate to obtain the intermediate compound BE-4 , 4-0H and in step b) said intermediate compound BE-4.4-0H is reacted with stoichiometric methacrylic acid in the presence of dimethylformamide as solvent and triethanol amine to give compound 4,4'-bis [ 2-hydroxy-3-methacryloxypropoxy] biphenyl (MB-4,4-0H) according to the following reaction scheme:

In another preferred embodiment of the invention, the 4,4'-bis [2-hydroxy-3-methacryloxypropoxy] biphenyl monomer of formula MB-4,4-0H is obtained by a method comprising the step of reacting the compound of 4,4- biphenol with glycidylmethacrylate in the presence of a solvent to obtain the compound 4,4'-bis [2-hydroxy-3-methacryloxypropoxy] biphenyl of formula MB-4,4-OH:

Preferably, the 4,4-biphenol compound with the glycidyl methacrylate is reacted in a stoichiometric ratio of 1: 2.5, using triethylamine and hydroquinone as an inhibitor and dimethylformamide as a solvent according to the following reaction scheme:

In another preferred embodiment of the invention, the 1,4-bis [(2- hydroxy-3-methacryloxy propoxy) methyl] phenyl monomer of formula MB-Fen-OH is obtained by means of a process comprising the steps of a) Reacting 1,4-benzenedimethanol and epichlorohydrin in the presence of a solvent to give the intermediate compound BE-Fen-OH of the formula:

 BE-Fen-OH b) reacting said BE-Fen-OH intermediate compound with methacrylic acid in the presence of a solvent to obtain the 1,4-bis [(2-hydroxy-3-methacryloxyl propoxy) methyl compound ] phenyl of formula MB-Fen-OH:

Preferably, in step a) of the process for obtaining the monomer 1, 4-bis [(2-hydroxy-3-methacryloxypropoxy) methyl] phenyl of formula MB-Fen-OH, compound 1 is reacted, 4-benzenedimethanol and epichlorohydrin, in the presence of sodium hydride as catalyst and DMF as solvent to obtain the intermediate compound BE-Fen-OH and in step b) said intermediate of formula BE-Fen-OH is reacted with methacrylic acid in presence of dimethylformamide and triethanol amine according to the following reaction scheme:

In another preferred embodiment of the present invention, the 1,4-bis [2-hydroxy-3-methacryloxypropoxy] butane monomer of formula MB-1,4-0H is obtained by a method comprising a) reacting 1.4 -butanediol and epichlorohydrin in the presence of a solvent to obtain the intermediate compound of formula BE-1,4-OH:

BE- -OH _and b) reacting said intermediate compound BE-1,4-0H with acrylic acid in the presence of a solvent to obtain said compound of formula MB-1,4-0H

MB-L4-ÜM Preferably, in step a) 1,4-butanediol and epichlorohydrin are reacted in the presence of sodium hydride as catalyst and dimethylformamide as solvent to obtain the intermediate compound of formula BE-1,4-0H, and in step b) Said intermediate compound BE-1,4-0H is reacted with acrylic acid in a stoichiometric ratio of 1 to 2.5 in the presence of triethanolamine and dimethylformamide as solvent to obtain said compound of formula MB-1,4-0H according to The following reaction scheme:

Step) Step 2

In another preferred embodiment of the invention, the monomer (Z) -l, 4-bis [2- hydroxy-3-methacryloxy propoxy] -2-butene of the formula MB-Cis-OH is obtained by a process comprising the steps of : a) reacting the cis-2-buten-l, 4-diol and epichlorohydrin compound in the presence of a solvent to obtain the intermediate compound of formula BE-cis-OH

Y b) reacting said BE-Cis-OH intermediate compound with acrylic acid in the presence of a solvent to obtain the compound of formula MB-Cis-OH

 Ί L-OH

Preferably, in step a) the cis-2- buten-1,4-diol compound and the epichlorohydrin are reacted in the presence of sodium hydride as catalyst and dimethylformamide as a solvent to obtain the intermediate compound of formula BE-cis- OH, and in step b) said BE-Cis-OH intermediate compound is reacted with acrylic acid in a stoichiometric ratio of 1 to 2.5 in the presence of triethanolamine as catalyst and dimethylformamide a solvent to obtain the compound of formula MB- Cis-OH according to the following reaction scheme:

Step 2

C

or

I ^" and" o-

OH OH

IVIB-Cis-OH

A further embodiment of the invention the monomer l, 7-bis [2-hydroxy-3-methacryloxy propoxy] heptane of formula MB-l, 7-OH, is obtained by means of a process comprising the steps of: a) react 1,7-heptanediol and epichlorohydrin in the presence of a solvent to obtain the intermediate compound of formula BE-1,7-OH

BE-1/7-OH and b) react the intermediate compound BE-l, 7-OH in the presence of a solvent and a catalyst to obtain the compound of formula MB-l, 7-OH:

Preferably, in step a) 1,7-heptanediol and epichlorohydrin are reacted in the presence of a dimethylformamide as solvent and sodium hydride as catalyst to obtain the intermediate compound of formula BE-1, 7-OH and in step b ) the intermediate compound BE-l, 7-OH is reacted in the presence of dimethylformamide as solvent and triethanolamine to obtain the compound of formula MB-l, 7-OH according to the following reaction scheme:

A further object of the invention relates to dental restoration resin formulations comprising said monomers. Experimental part

Team

Nuclear Magnetic Resonance (NMR) spectra were performed on a JEOL Eclipse +400 spectrometer, using as deuterated chloroform solvent (CDCI ₃ ) at 400 MHz for - H and at 100 MHz for - ¹³ C, using the tetramethylsilane compound (TMS) as reference Chemical shifts (δ) are expressed in ppm. The coupling constants (J) are expressed in Hz. The multiplicity of the signals in the NMR spectra is abbreviated as s: singlet, d: doublet, t: triplet and m: multiplet.

 IR spectra were obtained on a Perkin Elmer FT-IR System 2000 infrared spectrophotometer with Fourier transform (IR-FT). Preparing KBr tablets.

 Scanning electron microscopy (SEM) images were obtained from a JEOL model JSM6300.

 The images of the nanoparticles of the inorganic filler silanized and without silanizing were obtained from a Transmission Electron Microscope (TEM) brand JEOL model JEM 21-00. The samples were prepared by placing a drop of colloidal solution on a copper grid covered with a layer of amorphous carbon and drying under vacuum.

 All reactions were monitored by thin layer chromatography using silica gel and alumina chromatoplacs with a 0.22 mm layer thickness as the stationary phase; various solvent mixtures were used as the mobile phase. As a developer, a Blue-Stain solution and a UV lamp were used.

The polymerizations were made with a Bluephase® light curing unit (Ivoclar-Vivadent) equipped with a visible LED light, which has the possibility of varying the intensity of the light emitted in a range of 1200 mW / cm ² to 460 mW / cm ²

 The dimensions of the specimens were measured using a Mitutoyo digital caliper (Mod. CD-6 "C Mitutoyo corp. Japan).

The 3-point bending test was performed on an Instron universal testing machine (Instron model 1100 Mas USA). Reagents and solvents.

 The different reagents and solvents used for the synthesis of the compounds reported in the present work are described in Tables 4 and 5. The solvents were purified and dried according to the techniques described in the literature (87, 88); The rest of the reagents were used as received.

Table 4 Solvents used

methanol ethanol

CH3OH _H CH _3- CH ₂ -OH

Brand: Sigma, P ⁰ Brand: Sigma Aldrich

 H

 Aldrich

 Molecular weight:

Molecular Weight: 32.04 g / mol 46.07 g / mol HH _H

 H-C-C-O '

Density: 0.791 g / cm ³ Density: 0.789 "g / cm ³

 Boiling Point: 65 ° C

 Boiling Point: 78 ° C

ethyl acetate

CH ₃ COOC ₂ H ₅

 Brand: Sigma 0

 Aldrich

 Molecular Weight: 88.11 g / mol

Density: 0.897 g / cm ³

Boiling Point: 77 ° C

Table 5 List of Reagents used

Density: 1,072 _M0 -OH Density: 1,017 ^HO - - ₀ H g / cm ³ g / cm ³

Boiling Point: 235 ° C Boiling Point: 235 ° C

1,7-heptanediol 4,4-biphenol

 Brand: Sigma Aldrich Brand: Sigma

 Aldrich ^ ... ^ .. ^ - o »

Molecular weight:

132.20 g / mol _or Molecular Weight: 186.21 g / mol

Density: 0.951 g / cm ³ Melting point: 280 ° C

Boiling Point: 259 ° C

sodium hydride

 1,4-benzenedimethanol

 Brand: Sigma

 Brand: Sigma ^ v "-. Aldrich

 Aldrich Molecular Weight: 24 g / mol

 Molecular Weight: 138.16

 Melting point: 800 ° C g / mol

 Melting Point: 114 ° C

triethylamine epichlorohydrin

 Brand: Sigma Aldrich Brand: Sigma Aldrich

 Molecular Weight: Molecular Weight:

101.19 g / mol

92.52 g / mol

Density: 0.7255 g / cm ³ Density: 1.1812 g / cm ³

Boiling Point: 90 ° C Boiling Point: 117, 9 ° C

glycidyl methacrylate methacrylic acid ^{hC JÍ} -OH Brand: Sigma Aldrich Brand: Sigma Aldrich

 Molecular Weight: o Molecular Weight: 86.09 g / mol r- 1

 142.15 g / mol b

Density: 1,015 g / cm ³

Density: 1,042 g / cm ³

 Boiling Point: 163 ° C

Boiling Point: 189 ° C

4-dimethylaminobenzoate from: hydroquinone

^"■■ f ethyl Brand: Sigma Aldrich OH

Brand: Sigma Molecular Weight: 110.11 g / mol

Aldrich ^

 Melting Point: 172 ° C Molecular Weight: 193.24 g / mol

Melting Point: 63 ° C

camphorquinone

 3- (trimethoxysilyl) propyl

 Brand: Sigma Methacrylate

 Aldrich

Brand: Sigma Molecular Weight:

Aldrich ^ - ^ r * ¹ 166.22 g / mol

 Molecular Weight: 248.35 g / mol

 Melting Point: 197 ° C

Density: 1,045 g / mL

Melting Point: 190 ° C

bisphenol A Dimethacrylate; Triethylene glycol dimethacrylate; Glyceryl Brand: Sigma Aldrich

 Brand: Sigma Aldrich Molecular Weight: 286.32 g / mol

Molecular Weight: 512.59 g / mol

From

i ^ J ...-. ...... ^" ^ ÜL ....-. J ... ^ ^nsi Density: 1,092 g / mL

 " " gives

 d: 1,161 g / mL

Synthesis of the Monomers.

Synthesis of the 4,4'-bis [2-hydroxy-3-methacryloxypropoxy] biphenyl) [MB-4,4-OH] monomer.

The synthesis of the MB-4,4-0H monomer was carried out in two different synthetic routes. The first route of synthesis is illustrated below and consists of a two-stage reaction. The first reaction stage consists in the synthesis of intermediate BE-4,4-0H by means of an etherification reaction between 4,4'-biphenol and epichlorohydrin.

Two-step synthetic route for MB-4,4-OH monomer

In a two-mouth ball equipped with magnetic stirrer, 1 g (5 mmol) of 4,4-biphenol and 6 g (21 mmol) of K ₂ C0 ₃ and 10 mL of DMF were added as solvent. The flask was placed in a water bath where the reaction temperature was brought to 55 ° C. Once this temperature was reached, 1.18 g (12 mmol) of epichlorohydrin dissolved in 5 mL of DMF was slowly added. The reaction was maintained under an atmosphere of argon and constant stirring for 12 hours at 55 ° C and continued at room temperature for an additional 48 hours. After this time, 40 mL of acetone was added to the reaction medium and kept under stirring for a period of 1 hour. At the end of this period, the reaction medium was filtered under vacuum using a buchner funnel and a Whatman® filter paper of number 5. The filtered acetone was evaporated to obtain a white solid. The final compound was purified by the technique of recrystallization with ethanol, presenting itself as a white solid.

The compound was characterized by H NMR, ¹³ C NMR, FTIR and Elemental Analysis. NMR (CDCI ₃ , 400 MHz) δ (ppm): 7.46 (d, 4H, J _B , _C 8.7 Hz, H- B), 6.97 (d, 4H, J _C , _B 8.7 Hz, HC), 4.25 (dd, 2H, J _Ea , Eb ll, 0 Hz, J _Ea , _F 3, 1 Hz, H- Ea), 3.99 (dd, 2H, J _Ea , _E b 11 , 0 Hz, J _Ea , _F 5.7 Hz, H-Eb), 3.38 (m, 2H, HF), 2.92 (t, 1H, JG _a , _Gb ≡ J _Ga , _F 4.5 Hz , H-Ga), 2.92 (dd, 2H, JG _b , _Ga 4.9 Hz, JG _b , _F 2.7 Hz, H-Gb). ¹³ C NMR (CDCI ₃ , 100 MHz) δ (ppm): 157.61 (CA), 133.82 (CD), 127.75 (CB), 114.86 (CC), 68.80 (CE), 50, 16 (CF), 44.73 (CG). IR (KBr, cm ¹ ): 2909 (u _sim -CH) 1606, 1500

C Ar), 1247 and 1037 (C- O OC _asym), 1133 (C-O _sim 0-C), 910, 863 and 762 (epoxide skeleton vibration). Elemental Analysis: calculated for Ci ₈ Hi ₈ 0 ₄ : C, 72.47; H, 6.08. . Found: C, 71.67; H, 5.96.

In a second step, the formation of an ester group attached to the vinyl group was carried out by reacting the intermediate compound BE-4,4-0H with methacrylic acid in a stoichiometric ratio of 1: 2.5, using triethylamine, in a concentration of 2% and DMF as solvent. In a two-mouth ball protected from light with aluminum foil, and equipped with magnetic stirrer and thermometer, 0.5 g (16 mmol) of intermediate compound BE-4.4-0H, 0.3 g (41 mmol) were added ) of methacrylic acid, 0.16 g (16 mmol) of triethylamine and 2.5 ml of DMF as solvent. The temperature of the reaction medium was raised to 60 ° C under an atmosphere of argon and constant stirring for 12 hours. After this period of time, it was left under constant stirring at room temperature for an additional 48 hours. At the end of the reaction, 20 ml_ of distilled water were added, forming a white precipitate. Said solid was filtered with a funnel coors and Whatman filter paper of number 5. After having been filtered and dried, the bifunctional monomer was obtained as a white solid.

A second route to obtain the MB-4,4-0H monomer consists of a one-step reaction in which the 4,4-biphenol was reacted with the glycidyl methacrylate, in a stoichiometric ratio of 1: 2.5, using 2% triethylamine by weight as catalyst and 2% hydroquinone by weight as inhibitor.

Second route to obtain the MB-4,4-OH monomer

In a two-mouth ball, equipped with a magnetic stirrer and thermometer, 1 g (5 mmol) of 4,4-biphenol, 1.9 g (13 mmol) of glycidyl methacrylate, 0.05 g of hydroquinone, 0.05 were added g of triethylamine and 2 ml_ of DMF as solvent. The flask was protected from light and placed in a heating blanket at a temperature of 60 ° C. The reaction was maintained under an atmosphere of argon and constant stirring for 18 hours. After that time, 40 ml_ of distilled water were added, observing the precipitation of a light brown solid. Said solid, once dry, was washed successively with ethanol. The resulting solid was filtered using a kitasate flask and a coors funnel equipped with a Whatman paper of number 5; once dried, the bifunctional monomer was obtained as a white solid.

IR and NMR spectroscopy proved to obtain the monomer. NMR (CDCI3, 400 MHz) δ (ppm): 7.46 (d, 4H, J _BC 8.7 Hz, HB), 6.97 (d, 4H, J _C , B8.7 HZ, HC), 4 , 41 (dd, 2H, J _EA , _EB 11.5 Hz, J _EA , _F 4.9 Hz, H-Ea), 4.37 (dd, 2H, J _Eb , Ea 11.5 Hz, J _Eb , _F 5.2 Hz, H-Eb), 4.31 (m, 2H, HF), 4.11 (dd, 2H, J _Ga , Gb 9.6 Hz, J _Ga , _F 4.6 Hz, H- Ga), 4.09 (dd, 2H, J _Gb , _Ga 9.5 Hz, J _Gb , _F 5.8 Hz, H- Gb), 6.16 (s, 2H, H-Ka), 5.62 (t, 2H, J _KJ 1.4 Hz, H-Kb), 1.97 (s, 6H, HJ). ¹³ C NMR (CdCI ₃ , 100 MHz) δ (ppm): 133.6 (CA), 127.8 (CB), 114.5 (C-C), 157.5 (CD), 65.5 (CE , CG), 68.6 (CF), 167.2 (CH), 135, 9 (CI), 18.2 (CJ), 126.2 (CK). IR (KBr, cm-1): 3471 (υΟ-Η), 2926 (OCH), 1697 (υ- C = 0), 1638 (uC = C), 1600, 1500 (uC = C Ar), 1456 (δ -CH), 811 (5C = C). Elemental Analysis: calculated for Ci ₈ Hi ₈ 0 ₄ : C, 66.37; H, 6.43. . Found: C, 65.89; H, 6.16.

Synthesis of the monomer l, 4-bis [(2-hydroxy-3-methacryloxy propoxy) methyl] phenyl [MB-Fen-OH].

The synthesis route used to obtain the MB-Fen-OH monomer is described. The synthetic route consisted of a two stage reaction. The first step is to synthesize the intermediate compound BE-Fen-OH from the etherification reaction between 1,4-benzenedimethanol and epichlorohydrin, using sodium hydride as the base and DMF as solvent. Step i Step;

Synthesis of MB-FE-OH monomer

 In a two-mouth ball equipped with a magnetic stirrer and under an argon atmosphere, 1 g (7 mmol) of 1,4-benzenedimethanol was added together with 0.43 g (18 mmol) of sodium hydride suspended in 10 mL of DMF The system was placed inside a water bath at a temperature of 60 ° C. Subsequently, the reaction was brought to room temperature and 1.6 g (18 mmol) of epichlorohydrin were added. The reaction continued at room temperature for 24 hours. At the end of this time, 30 mL of distilled water were added and subsequently extracted (3 times) with ethyl ether. The organic fraction was separated and 5 grams of sodium sulfate were added to dry. Once dried, the organic fraction was filtered and then concentrated with the help of a rotary evaporator, resulting in a viscous amber liquid.

The column chromatography technique was used for purification of the compound, using alumina and a mixture of cyclohexane: acetone (9: 1) as the mobile phase as the stationary phase. The identification of the portions in which the pure compound is presented was made by making chromatoplates. Once the fractions containing the expected compound were collected, they were evaporated and BE-Fen-OH was obtained as a yellow viscous liquid.

The compound was characterized by H NMR, ¹³ C NMR, FTIR and Elemental Analysis. NMR (CDCI ₃ , 400 MHz) δ (ppm): 7.34 (s, 4H, HA), 4.62 (d, 2H, J _Ca , cb 11.9 Hz, H-Ca), 4.54 ( d, 2H, J _Cb , c _at 11.9 Hz, H-Cb), 3.77 (dd, 2H, J _Da , _Db 11.4 Hz, J _Da , _E 2.9 Hz, H-Da), 3.43 (dd, 2H, J _Db , _Da 11.9 Hz, J _DbE5 5.9 Hz, H-Db), _3.19 (m, 2H, H-5), 2.81 (dd, 2H, J _FaFb 4.9 Hz, J _Ca-E 5 4.2 Hz, H-Fa), 2.62 (dd, 2H, J _Fab , _Fa 5.0 Hz, J _Fb , _E 2.6 Hz, H- Fb). ¹³ C NMR (CDCI ₃ , 100 MHz) δ (ppm): 128.00 (CA), 137.57 (CB), 73, 17 (CC), 70.90 (CD), 50.88 (CE), 44.30 (CF). IR (KBr, cm-1): 1701 (uC = C), 1364 (C-O _asym 0-C), 914 (O _sim C- OC), 914 (epoxide group). Elemental Analysis: Ci ₄ Hi ₈ 0 ₄ (calculated) experimental:% C (67, 18) 64.21,% H (7.25) 9.01,% 0 (25.57) 26.78.

In a second step, the intermediate compound previously synthesized was reacted with methacrylic acid, in the presence of triethylamine, to form a bimetacrylic ester.

The compound was characterized by H NMR, ¹³ C NMR, FTIR and Elemental Analysis. NMR (CDCI ₃ , 400 MHz) δ (ppm): δ: 7.24 (s, 4H, HA), 4.49 (s, 4H, HC), 3.52 (dd, 2H, J _Da , _Db 9 , 5 Hz, J _Da , _E 4.4 Hz, H-Da), 3.45 (dd, 2H, J _Db , _Da 9.5 Hz, J _Db , _E 5.9 Hz, H-Db), 4 , 01 (m, 1H, HE), 4.20 (dd, 2H, J _Fa , _Fb 11.5 Hz, J _Fa , _E 5.3 Hz, H-Fa), 4, 14 (dd, 2H, J _Fab , _Fa 11.7 Hz, J _Fb , 5, 1 Hz, H-Fb), 6.04 (s, 2H, H-Ib), 5.52 (t, 2H, J _HJ 1.5 Hz, H-Ia), 1.87 (s, 6H, HJ). ¹³ C NMR (CDCI ₃ , 100 MHz) δ (ppm): 127.87 (CA), 137.34 (CB), 73.18 (CC), 70.89 (CD), 68.90 (CE), 65.71 (CF), 167.39 (CG), 135.9 (CH), 126.03 (CI), 18.27 (CJ). IR (KBr, cm-1): 3464 (υΟ-Η), 2865 (or _equivalent CH), 1716 (uC = 0), 1636 (uC = C), 1455 (5-CH ₂ -), 813 (5C = C). Elemental Analysis: C ₂₂ H ₃₀ O ₈ (calculated) experimental:% C (62.55) 63.34,% H (7.16) 7.47,% 0 (30.30) 29.19.

Synthesis of the monomer l, 4-bis [2-hydroxy-3-methacryloxypropoxy] butane [ΜΒ-1,4-ΟΗ].

The synthesis route for obtaining the MB-1,4-0H monomer is described. Said synthetic route consisted of a two stage reaction. In the first stage, the intermediate compound BE-1,4-0H was synthesized from an etherification reaction between 1,4-butanediol and epichlorohydrin, in the presence of sodium hydride as a base and DMF as a solvent.

Step 1 Step 2

 MB-1.4-OH

Synthesis route for obtaining the MB-l, 4-OH monomer

In a two-mouth ball equipped with a magnetic stirrer, under an argon atmosphere, 1 g (11 mmol) of 1,4-butanediol was added together with 0.66 g (27 mmol) of sodium hydride dissolved in 5 ml_ of DMF The system was placed inside a water bath at a temperature of 55 ° C. Subsequently, 2.5 g (27) were added to the reaction mixture. moles) of epichlorohydrin previously dissolved in 5 ml_ of DMF. The addition of the components to the reaction medium was done slowly. The temperature was maintained in a range of 50-55 ° C for two hours and after that, it was kept at room temperature for an additional 24 hours. At the end of the reaction, 30 mL of distilled water was added. Subsequently, extractions (3 times) were carried out with ethyl acetate and ether. The organic fraction was separated and 5 grams of anhydrous sodium sulfate were added in order to remove as much water. Subsequently, the organic fraction was filtered and concentrated with the help of a rotary evaporator, observing a yellow liquid.

Purification of the compound was achieved by column chromatography, using alumina and a mixture of cyclohexane: acetone (9: 1) as the mobile phase as the stationary phase. By means of alumina chromatoplates the portions in which the isolated compound is presented and once collected and evaporated, the compound [BE-1,4-OH] was obtained as a yellow liquid.

The compound was characterized by ^ι Η NMR, ¹³ C NMR, FTIR and Analysis. NMR 'H (CDCI ₃ , 400 MHz) δ (ppm): 3.73 (m, 2H, H-Ca), 3.52 (m. 4H, HB), 3.39 (m, 2H, H-Cb ), 3.15 (m, 2H, HD), 2.81 (m, 2H, H-Ea), 2.62 (m, 2H, H-Eb), 1.67 (m, 4H, HA). ¹³ C NMR (CDCI ₃ , 100 MHz) δ (ppm): 26.27 (CA), 71, 18 (CB), 71.38 (CC), 50.85 (CD), 44.24 (CE). FTIR (KBr, cm ¹ ): 1254, 1204 (O _sim C-0-C), 1107 (O _sim C-0-C), 856 (epoxy group). Elemental Analysis: Ci ₀ Hi ₈ O ₄ (calculated) experimental:% C (59.37) 57.78,% H (8.98) 8, 13,% 0 (31.65) 34.09.

In the second stage, a dimethacrylic monomer was formed from the intermediate compound [BE-1,4-0H] and methacrylic acid, the reaction was performed in a stoichiometric ratio of 1 to 2.5. 2% by weight of triethylamine was used as base and DMF as solvent.

In a two-mouth ball equipped with magnetic stirrer, thermometer and light cover, 0.3 g (1.4 mmol) of the intermediate compound, 0.38 g (4.4 mmol) and 0.03 mL of Triethylamine dissolved in 5 mL of DMF. The reaction temperature was brought to 60 ° C and was maintained under an argon atmosphere for 24 hours.

The compound was characterized by ^ι Η NMR, ¹³ C NMR, FTIR and elemental analysis. NMR (CDCI ₃ , 400 MHz) δ (ppm): 1.66 (t, 1H, J _A , _B 3.7; HA), 3.50 (m, 2H; H-Ca, H-Cb), 4 , 04 (m, 3H; HB, HD), 4.23 (d, 2H; H-Ea, H- Eb), 6, 14 (s, 1H; H-Ha), 5.60 (t, 1H, J _Hb , i 1.4 Hz; H-Hb), 1.95 (s, 3H; HI). ¹³ C NMR (CDCI ₃ , 100 MHz) δ (ppm): 26, 17 (CA), 71.54, 71.20 (CB and C-C), 68.69 (CD), 65.65 (CE) , 167.32 (CF), 135.86 (CG), 125.91 (CH), 18.20 (CI). IR (KBr, cm ¹ ): 3444 (υΟ-Η), 2928 (uC-H), 1718 (uC = 0),

. Elemental Analysis: Ci ₈ H ₃ o0 ₈ (calculated) experimental:% C (57.74) 56.81,% H (8.08) 8.28,% 0 (34, 18) 34.91.

Synthesis of monomer (Z) -l, 4-bis [2-hydroxy-3-methacryloxy propoxy] -2-butene [MB-Cis-OH].

The synthesis method for this monomer consists of a two stage reaction. In the first stage, an ether was synthesized from the reaction between cis-2-buten-l, 4-diol and epichlorohydrin in a 2.5 to 1 molar ratio, using sodium hydride and DMF as solvent. . Step 1 Step 2

C

 MB-Cis-OH

Synthesis method for MB-Cis-OH monomer

 In a two-mouth ball equipped with a magnetic stirrer, 1 g (11 mmol) of cis-2-buten-1, 4-diol were added together with 0.68 g (28 mmol) of HNa dissolved in 5 mL of DMF. The balloon was placed in a water bath and the reaction temperature was brought to 55 ° C. At this temperature, 2.62 g (28 mmol) of epichlorohydrin dissolved in 5 mL of DMF were added. The reaction was maintained under an atmosphere of argon and constant stirring for 2 hours at 55 ° C and then at room temperature for an additional 24 hours. After this time, 30 mL of distilled water was added to remove excess hydride and extractions were carried out with ethyl acetate (3 times) and ether (3 times). The organic part was collected, dried with anhydrous sodium sulfate, the solvent was evaporated.

Purification of the compound was carried out by the column chromatography technique, using alumina and a cyclohexane: acetone (9: 1) mixture as the mobile phase as the stationary phase. Once the tubes containing the diepoxide compound were identified, they were collected in a ball flask and the solvent was evaporated in a rotary evaporator. The expected compound was obtained as a yellow liquid.

The compound was characterized by H NMR, ¹³ C NMR, FTIR and Elemental Analysis. NMR (CDCI ₃ , 400 MHz) δ (ppm): 5.74 (m, 2H, J _A , B 4.8 Hz, HA), 4.13 (d, 4H, J _B , _A 4.8 Hz, HB), 3.75 (dd, 2H, J _Ca , c _b 11.5 Hz, J _Ca , _D 2.9 Hz, H-Ca), 3.38 (dd, 2H, J _Cb , c _to 11, 4 Hz, J _Cb , _D 5.9 Hz, H-Cb), 3, 16 (m, 1H, HD), 2.81 (dd, 1H, J _Ea , _Eb 4.9 Hz, J _Ea , _D 4 , 2 Hz, H-Ea), 2.61 (dd, 1H _,, J _Eab , _Ea 5.0 Hz, J _Eb , _D 2.6 Hz, H-Eb). ¹³ C NMR (CDCI ₃ , 100 MHz) δ (ppm): 129.37 (C-1), 66.97 (C-2), 71.00 (C-3), 50.88 (C-4) 44.30 (C-5). IR (KBr, cm ¹ ): 1254, 1095 (O _sim C-0-C), 1011 (½ _m C-0-C), 761 (epoxy group). Elemental Analysis: Ci ₀ Hi ₆ O ₄ (calculated) experimental:% C (59.98) 55.02,% H (8.05) 11.32,% 0 (31.97) 33.66.

For the second stage, bismetacrylic monomer was formed from BE-Cis-OH and methacrylic acid in a stoichiometric ratio of 1 to 2.5, using 2% by weight triethylamine catalyst with respect to the above reagents and using DMF as a solvent.

In a two-mouth balloon equipped with a mechanical stirrer and thermometer, 0.5 g (2.4 mmol) of BE-Cis-OH, 0.5 mL (6 mmol) of methacrylic acid and 0.02 mL of triethylamine dissolved in 2.5 mL of DMF. The flask was placed in a heating blanket and the temperature was brought to 55 ° C. The reaction was kept under stirring, with an argon atmosphere and covered with light with aluminum paper for a period of 18 hours. For the purification of the compound, the column chromatography technique was used, using silica gel as stationary phase and a mixture of dichloromethane: acetone (9: 1) as mobile phase. Once the impurities were separated, 150 mL of ethanol was passed to carry the expected compound. The ethanol was collected and after evaporation, an amber liquid was obtained.

The compound was characterized by H NMR, ¹³ C NMR, FTIR and Elemental Analysis. NMR (CDCI ₃ , 400 MHz) δ (ppm): CDCI ₃ ) δ: 6, 14 (s, 2H; daughter), 5.75 (t, 2H, HA), 5.60 (t, 2H, H- Jb), 4.22 (m, 4H; HF), 4, 11 (m, 4H; HB), 4.05 (m, 2H; HD), 3.52 (dd, 4H, HC), 1.92 (s , 6H; HI). ¹³ C NMR (CDCI ₃ , 100 MHz) δ (ppm): 167.39 (CG), 135.93 (CH), 129.34 (CA), 125.96 (CJ), 71, 17 (CB), 68.82 (CD), 66.94 (CF), 65.71 (CC), 18.26 (C-I). IR (KBr, cm ¹ ): 3441 (υΟ-Η), 2928 (DC-H), 1718

815 (5C = C). Elemental Analysis: Ci ₈ H ₂₈ 0 ₈ (calculated) experimental:% C (58.05) 56.80,% H (7.58) 7.77,% 0 (34.37) 35.43.

Synthesis of the monomer l, 7-bis [2-hydroxy-3-methacryloxy propoxy] heptane [MB-l, 7-OH].

The synthesis route for this monomer consists of a two stage reaction. During the first stage, synthesis of intermediate BE-1,7-OH takes place by means of an etherification reaction between 1,7-heptanediol and epichlorohydrin.

 Step 1 Step 2

Synthesis path for MB.1,7-OH monomer In a two-mouth ball equipped with magnetic stirrer, 0.90 g (28 mmol) of sodium hydride dissolved in 10 mL of DMF was added. After stirring, 2 g (15 mmol) of 1,7-heptanediol and 3.4 g (37 moles) of epichlorohydrin were added slowly. The flask was placed in a water bath and the reaction was maintained under an atmosphere of argon and constant stirring for 12 hours at 55 ° C. At the end of the reaction, 50 mL of acetone was added, which was filtered and evaporated, obtaining a light yellow liquid. In order to eliminate DMF and facilitate the purification process, 4 extractions were made with cyclohexane, which, when evaporated, led to a dark brown liquid.

The purification was carried out by the column chromatography process, using silica as the stationary phase and a dichloromethane-ethyl acetate mixture (8: 2) as the mobile phase. Once the tubes containing 1,7-heptanediol diepoxide were identified, they were collected in a flask and when the solvent evaporated, the expected compound was obtained as a light brown liquid.

The compound was characterized by ^ι Η NMR, ¹³ C NMR, FTIR and Elemental Analysis. NMR (CDCI ₃ , 400 MHz) δ (ppm): 3.71 (m, 2H, H-Ea), 3.49 (m, 4H, HD), 3.37 (m. 2H, H-Eb), 3.14 (m, 2H, HF), 2.79 (m, 2H, H-Ga), 2.61 (m, 2H, H-Gb), 1.59 (m, 4H, HC), 1, 33 (m, 6H, HA, HB). ¹³ C NMR (CDCI ₃ , 100 MHz) δ (ppm): 25.96 (CA), 29.21 (CB), 29.56 (CC), 71.57 and 71.41 (CD and CE), 50 , 85 (CF), 44.28 (CG). FTIR (KBr, cm-1): 1254, 1204 (O _sim C-0-C), 1107 (O _sim C-0-C), 856 (epoxy group). Elemental Analysis: Ci ₀ H ₁₈ O ₄ (calculated) experimental:% C (59.37) 57.78,% H (8.98) 8, 13,% 0 (31.65) 34.09.

In a second stage, the formation of the vinyl monomer was achieved from the reaction between the compound BE-l, 7-OH and methacrylic acid in a stoichiometric ratio of 1: 2.5, using 2% triethylamine by weight and acetone as solvent.

In a two-mouth ball covered in light with aluminum foil, and equipped with magnetic stirrer and thermometer, 0.4 g (1.6 mmol) of the compound BE-l, 7-OH, 0.3 g (4) were added mmol) of methacrylic acid, 0.15 g (1.6 mmol) of triethylamine and 5 ml of acetone as solvent. The reaction was kept under stirring for 24 hours at 55 ° C and at room temperature for another 48 hours.

Purification of the compound was achieved by column chromatography using silica as the stationary phase and a mixture of hexane: acetone (1: 1) as the mobile phase. The expected compound is retained in the column, so once the tubes containing methacrylic acid and unreacted BE-1, 7-OH have been identified, the mobile phase is changed to ethanol. Once collected, it was concentrated in the rotary evaporator and the monomer is obtained as a brown liquid.

The compound was characterized by ^ι Η NMR, ¹³ C NMR, FTIR and Elemental Analysis. NMR (CDCI ₃ , 400 MHz) δ (ppm): 6.14 (s, 2H, H-Ja) 5.59 (t, 2H, H-Jb), 4.22 (m, 4H, HE), 4 , 05 (m, 2H, HF), 3.87 (m, 2H, HG), 3.68 (m, 4H, HH), 1.96 (s, 6H, HI), 1.56 (m, 4H , HC), 1.32 (m, 4H, HB), 1.25 (m, 2H, HA). ¹³ C NMR (CDCI ₃ , 100 MHz) δ (ppm): 26.17 (CA), 71.54, 71.20 (CB and CC), 68.69 (CD), 65.65 (EC), 167 , 32 (CF), 135.86 (CG), 125.91 (CH), 18.20 (CI). IR (KBr, cm ¹ ): 3444 (υΟ-Η), 2928 (uC-H), 1718

Elemental Analysis: Ci ₈ H ₃₀ O ₈ (calculated) experimental:% C (57.74) 56.81,% H (8.08) 8.28,% 0 (34.18) 34.91. Preparation and valuation of composite materials.

Silanization of the filling material.

The preparation and silanization of the filler material was done according to the technique described by Miyasaka (89).

 In a one-mouth ball flask, 4 g of nanometer-sized silica (0.2-0.3 μηη) dispersed in an ethanol / water solution (95/5%) were added in a 5% mass ratio. The flask was kept under stirring for 4 hours at room temperature. After that time, 0.4 g of 3-trimethoxysilylpropyl methacrylate were added, and the reaction was kept under stirring for another hour. Subsequently, the balloon was taken to the rotary evaporator and the ethanol was removed by evaporation. The filler material already silanized was dried in a high vacuum oven at a temperature of 60 ° C for 12 hours.

Preparation of composite materials.

 The method for the preparation of composite materials was carried out according to the technique described by Wilson et al. (90).

In a balloon 500 mg of the silanized filler material was added together with a solution of the organic matrix (monomers, CQ and E4DMA) dissolved in 90% ethanol followed by mechanical stirring for a period of two hours. After this time the ethanol was removed by evaporation under high vacuum and the system was then mixed manually until the composite material was obtained with adequate consistency. The composite materials obtained were placed in amber vials and kept refrigerated until use.

Assessment of flexural strength and flexural modulus.

The flexural strength of the prepared composite materials was evaluated based on the provisions of section 7.11 of the International Standard ISO-4049 Dentistry-Polymer-based filling, restoratve and luting materials (91), while the flexural modulus was evaluated according to the provisions of specification No. 27 ANSI / ADA (92).

Specimens of each 2 x 2 x 25 mm composite material were prepared in a stainless steel shaper or mold on a celluloid strip and a 1 mm thick slide. On the unpolymerized material, another celluloid strip was placed along with another slide exerting digital pressure for the removal of surpluses. Both the celluloid strip and the slide were maintained during the polymerization of the specimens.

The specimens were irradiated with an intensity of 460 mW / mm ² three times per side to give a total time of 90 seconds for each. The polymerization began in the center of the test tube and alternately on each side, overlapping already irradiated areas for a total of 3 on each side until the total length on both sides of the test piece was completed. Surpluses were removed with 600 and 1200 grain abrasive paper and their dimensions measured with an accuracy of 0.01 mm using a digital caliper. The specimens were kept in distilled water at 37 ° C until the time of the test.

The specimens were placed on two 2 mm diameter cylindrical supports, parallel to each other and at a distance between their centers of 20 mm for the three-point bending test in a universal testing machine, using a 1 kN load cell, with a spindle speed of 1 mm per minute, using the Series IX program for data capture.

Flexural strength was calculated using the following formula:

3FÍ

.Tsh ¹ '

Where:

σ = Flexural resistance [MPa] F = Force at the time of fracture [N]

 I = distance between supports [mm]

 b = width of the specimens [mm]

 h = height of the specimens [mm]

The flexural module was calculated using the following formula:

Where :

 E = Flexural modulus (MPa)

 Fi = Registered force where the deformation ceases to be directly proportional to the force recorded in the graph (N).

 1 = Distance between the two supports.

 b = Width of the specimen (mm)

 h = Height of the specimen (mm)

 d = Deflection of the specimen (mm)

The determinations of flexural strength and flexural modulus for each group evaluated were made in triplicate. These values were evaluated using the ANOVA statistical test to observe differences between the groups.

RESULTS

 Synthesis of the monomers.

The chemical structures of the new synthesized monomers were confirmed by using the proton ^ and ¹³ C Nuclear Magnetic Resonance Spectroscopy, Fou rier Transformed Infrared Spectroscopy and Elemental Analysis.

 -Cis-OH

 MB-1.7-OH

Structure of synthesized bisglycidyl methacrylate monomers

Characterization of the compound 4,4'-bis (oxirane-2-ylmethoxy) biphenyl [BE-4,4-OH]

 As described in the experimental section, the MB-4,4-OH monomer was obtained in a two-step reaction, where the compound BE-4,4-OH is used as a precursor.

Physical Properties

The intermediate compound BE-4,4-0H is a white powder soluble in ethanol, methanol and partially soluble in acetone. Its melting point is of 160 ° C and its molecular weight of 298.33 g / mol. This compound was obtained with a yield of 37.23%.

Elemental Analysis

The composition and purity of compound BE-4,4-0H was obtained through the elemental analysis technique. Table 6 shows the experimental values that were obtained, which coincide with those calculated for the expected compound. Also, according to this values, the purity with which this compound was obtained was 98.89%.

Table 6 Elemental Analysis for compound BE-4,4-OH

 Element%%

 Experimental Calculated

C 72.47 71.67

Or 21.45 22.37 *

H 6.08 5.96

Infrared Spectroscopy Analysis

The IR-FT spectrum of compound BE-4,4-0H is presented in Figure 1. The main bands that give evidence of the formation of this compound are: symmetric and asymmetric elongation bands at 1133, 1247 and 1037 cm ^"1 corresponding to the OC-OC group, as well as the 910 cm band ^{" 1} corresponding to the vibration of the skeleton of the epoxy ring. Similarly, the absence of the band between 3200 and 3600 corresponding to stretch υΟ-Η bond present in the starting material, ^4,4' -bifenol confirms the structure of the expected compound.

NMR spectroscopy of ¹ H and ¹³ C The ¹ H NMR spectrum of the BE-4.4-0H compound is shown in Figure 2, in which seven signals with a total integration of eighteen protons corresponding to the expected compound are presented. The signals are presented in the range of 7.46 to 2.77 ppm. The double signals at 7.46 and 6.97 ppm correspond to the protons of the aromatic rings, both signals integrate for a total of eight. Multiple signals at 4.25 and 3.99 ppm correspond to saturated methylene -CH ₂ - bound to oxygen, both signals have an integration of two protons. The multiple signal at 3.38 ppm integrates for two protons and corresponds to the proton of the methine present in the epoxy skeleton. Finally, at 2.92 and 2.77 ppm there are two multiple signals that integrate for a total of four protons and correspond to the methylene groups located within the epoxy skeleton.

Figure 3 shows the ¹³ C NMR spectrum of biepóxido compound synthesized from ^4,4' -bifenol. In it, seven signals are present in a range of 157.6 to 44.7 ppm. The signal at 157.6 ppm corresponds to the quaternary carbon of the aromatic ring located on the side of the ether (aromatic) functional group. The signal at 133.9 ppm comes from the signal emitted by the quaternary carbons of the aromatic rings in the center of the (aromatic) molecule. The signals at 122.7 and 114.9 ppm come from the rest of the carbons that make up the aromatic ring. The 68.8 ppm signal corresponds to the methylene carbon located next to the ether functional group. The signal at 50.2 ppm corresponds to the carbon of the methine present in the skeleton of the epoxide (epoxide). Finally, the signal presented at 44.7 ppm is from the carbon of the methylene corresponding to the epoxide.

Characterization of the compound 4,4'-bis [2-hydroxy-3- methacryloxypropoxy] biphenyl) [MB-4,4-OH]. The MB-4,4-0H monomer was obtained from two synthetic routes; The first one was a two-step reaction, where synthesis and purification of the intermediate compound described in the previous section was required. In a second synthetic route, the monomer was obtained from a single step reaction. In both synthetic routes the bifunctional monomer was obtained.

Physical Properties

 The compound MB-4,4-0H is a white powder with a melting point between 134 and 138 ° C, with a molecular weight of 470, 19 g / mol. It is soluble in THF, partially soluble in acetone and insoluble in hexane, cyclohexane, dichloromethane, ethanol and methanol. The yield for obtaining this monomer was 67% for the synthetic two-step route, while for the one-step route, the yield was 45%.

Elemental Analysis

The composition and purity of compound MB-4,4-0H was obtained by elemental analysis technique. The values obtained by this technique are observed in Table 7. These values coincide with the values calculated for the expected compound.

Table 7 Elemental Analysis for compound MB-4,4-OH

 Element%%

 Experimental Calculated

C 66.37 65.89

Or 27.20 27.95 *

H 6.43 6.16

From these results, it can be established that the purity of the compound is 99.2%. Infrared Spectroscopy Analysis

The infrared spectrum for the compound MB-4,4-0H is shown in Figure 4. The bands present in this spectrum that give evidence of the formation of this compound are: the presence of the signal at 3471 cm ^"1 , the which corresponds to the stretching of the υΟ-Η bond, which is formed in the molecule, in addition to the bands located at 1638 and 811 cm ^"1 , which correspond to the stretching and torsion of the C = C bond respectively. Likewise, the presence of the signal in 1697 cm ^"1 , which corresponds to the stretching of the link

from methacrylic acid, confirms the formation of the monomer. Finally, further evidence is the absence of the signal at 910 cm ^"1 , which corresponds to the vibration of the skeleton of the epoxy ring present in the intermediate compound and which does not occur in the bifunctional monomer.

NMR Spectroscopy of ^ and ¹³ C

In the NMR spectrum of the MB-4,4-0H monomer nine signals are presented with a total integration of thirty protons corresponding to the expected compound. The signals are presented in the range of 7.46 to 1.97 ppm. The double signals that appear at 7.46 and 6.97 ppm, integrate for a total of eight protons and are assigned to the protons of the two aromatic rings present in the molecule. The simple signals that appear at 6, 16 and 5.62 ppm represent the two different protons from unsaturated methylene (CH ₂ = C) at each end of the molecule, said signal integrates for four protons. The multiple signals present at 4.41 and 4.37 ppm integrate for a total of four protons, and come from the protons of the methylene group attached to the oxygen from the alcohol (Ar-0-CH ₂ -). In a displacement of 4.31 ppm a multiple signal is distinguished that integrates for two protons, said signal corresponds to the proton of the methine group (-CH-) presented by the monomer). In 4, 11 and 4.09 ppm there are two multiple signals that integrate for a total of four protons, which correspond to the protons of the methylene group attached to oxygen from methacrylic acid (-CH ₂ -0-C). Finally, a simple signal at 1.97 ppm is assigned to the protons of the methyl group that are at the ends of the molecule (-CH ₃ ), which signal gives a total integration for six protons. The corresponding spectrum is presented in Figure 5.

The ¹³ C NMR spectrum for this compound is presented in Figure 6. A total of ten signals in a range of 167.2 to 18.3 ppm can be observed, which correspond to the expected signals for the synthesized compound. In low fields, the first signal, at 167.2 ppm, comes from the carbon of the carbonyl group belonging to methacrylic acid (-C = 0). The signal at a displacement of 157.5 ppm corresponds to the carbon of the aromatic ring that is attached to oxygen (Ar). The signal located at 135.9 ppm is assigned to the quaternary carbon of the vinyl bond from methacrylic acid (C = CH ₂ ). At a chemical shift of 133.6 ppm, the signal that comes from the carbons of the aromatic rings that are linked together (Ar-Ar) is located. In a chemical displacement of 127.8 ppm a signal appears that comes from one of the central carbons of the aromatic ring (B). At 126.2 ppm, the signal from the carbon of the unsaturated methylene group is located at the ends of the molecule (C = CH ₂ ). At a displacement of 114.5 ppm, the signal corresponding to one of the aromatic ring carbons (Ar-C) can be observed. Towards high fields, the signal that occurs in a chemical shift of 68.6 ppm belongs to the methine group present in the monomer (-CH-). The signal that appears at 65.5 ppm corresponds to the carbons of the methylene groups that are bound to oxygen (0-CH ₂ -CH-CH ₂ -0). Finally, at a displacement of 18.3 ppm, there is a signal that represents the carbon of the terminal methyl group (-CH ₃ ).

Characterization of compound l, 4-bis (ox¡rano-2-lmethoxy) benzene [BE-Fen-OH]

The precursor BE-Fen-OH was synthesized by reacting bis alcohol with epichlorohydrin in DMF, using HNa to generate the reactive species. A Once purified, this product was used for the synthesis of the MB-Fen-OH monomer.

Physical Properties

The compound BE-Fen-OH is a yellow liquid that has a molecular weight of 250.29 g / mol. This is soluble in dichloromethane, acetone and DMF and insoluble in hexane and ethyl acetate. The yield for this reaction was 27%.

Elemental Analysis

The composition and purity of the BE-Fen-OH compound was obtained by elemental analysis technique. The results of this can be seen in Table 8. The values obtained coincide with those calculated for this compound, demonstrating that it was obtained with a purity of 95.5%.

Table 8 Elemental Analysis for the BE-Fen-OH compound

 Element%%

 Experimental Calculated

C 67.18 64.21

O 25.57 26.78

H 7.25 9.01

Infrared Spectroscopy Analysis

The BE-Fen-OH compound was characterized by the Fourier transform infrared spectroscopy technique. The spectrum obtained by this technique is presented in Figure 7. In this spectrum some important bands can be observed that allow demonstrating the formation of the expected compound, among them are: elongation of the link

of the aromatic ring of the compound is represented by a very large signal located at a wave number of 1701 cm ^"1 , the symmetrical and asymmetric elongation bands at 914 and 1364 cm ^{" 1} corresponding to a terminal epoxy ring.

NMR Spectroscopy of ^ and ¹³ C

Figure 8 shows the NMR spectrum corresponding to the compound BE-Fen-OH. In the spectrum seven different signals can be observed that integrate for eighteen protons, which correspond to the expected compound. The signals appear in a range of 7.34 to 2.62 ppm. In low fields, the simple signal that is presented at 7.34 ppm, and which is composed of four protons, corresponds to the protons present within the aromatic ring (Ar). The double signal that appears at 4.62 ppm is composed of four protons and corresponds to the protons of the methylene group located between the oxygen and the aromatic ring (Ar-CH ₂ -0-). The multiple signals at 3.77 and 3.43 ppm correspond to the protons of the methylene groups that are between the oxygen and the epoxy ring (-0-CH ₂ -), both signals integrate for a total of four protons. The multiple signal located at 3.19 ppm is found by integrating two protons, which correspond to the metino groups located in the skeleton of the epoxy ring (D). Finally, the two multiple signals at 2.81 and 2.62 ppm, are integrated by two protons each and correspond to the protons of the methylene group found in the ring of the epoxy skeleton (E).

The ¹³ C NMR spectrum for this same compound can be seen in Figure 9. Six different signals appear in this spectrum that correspond to those expected for the synthesized compound. The signals appear in a range from 137.6 ppm to 44.3 ppm. The signal presented at 137.6 ppm corresponds to the carbon of the aromatic ring that is located next to the methylene group (B). At 128.0 ppm, a signal from the central carbons of the aromatic ring (A) is presented. The signal that It is presented at 73.7 ppm corresponds to the carbon of the methylene group that is between oxygen and the aromatic ring (Ar-CH ₂ -0-). At 70.9 ppm, a signal appears that comes from the carbon of the methylene group located between oxygen and the epoxy ring (-0-CH ₂ -). The signal presented at 50.9 ppm belongs to the carbon of the methine located inside the epoxide ring, while the signal at 44.3 ppm is originated by the carbon of the methylene group of the epoxy skeleton.

Characterization of the compound l, 4-bis [(2-hydroxy-3-methacryloxpropoxy) methyl] phenyl [MB-Fen-OH]

Physical Properties

The MB-Fen-OH monomer is a light yellow viscous liquid that has a molecular weight of 422.47 g / mol. This compound has solubility in acetone, dichloromethane and chloroform. The yield for the second stage of synthesis is 75.9%. The final yield for the synthesis of this monomer is 51.45%.

Elemental Analysis

The MB-Fen-OH compound was characterized by elemental analysis technique in order to know its composition and determine the purity with which it was obtained. Table 9 shows the results of this analysis; according to these, the purity of the synthesized monomer was 98.75%.

Table 9 Elemental Analysis for the compound MB-Fen-OH

 Element%%

 Experimental Calculated

C 62.55 63.34

O 30.30 29.19

H 7.16 7.47 Infrared Spectroscopy Analysis

Figure 10 shows the IR-FT spectrum obtained from the compound MB-Fen-OH. The spectrum shows evidence of the formation of the monomer when the following absorption bands occur: first, the signal that is presented at a wavelength of 3464 cm ^"1 , corresponds to the stretching of the υΟ-Η bond that is found as a group slope in the monomer structure; similarly, the absorption band located at 2865 cm ^"1 is assigned to the asymmetric stretch of the OC-H bond, at a wave number of 1636 and 813 cm ^{" 1} , are present the bands corresponding to the stretching and torsion of the link O-6C = C respectively. In a wave number of 1716 cm ^"1 , a signal is presented that is assigned to the link stretching

Finally, a band corresponding to the symmetric torsion within the plane of the 5-CH ₂ - link is presented at a wave number of 1455 cm -1. One more evidence of the formation of the compound is the absence of the signal at a wavelength of 910 cm ^"1 , which corresponds to the vibration of the skeleton of the epoxy ring, confirming the correct conversion of the epoxy ring into bimetacrylic ester.

NMR Spectroscopy of ^ and ¹³ C

Figures 1 1, 12 and 13 show the NMR spectra of ^ and ¹³ C of the compound MB-Fen-OH. In the NMR spectrum, eight signals can be distinguished that integrate for thirty protons, which were expected for the synthesized compound. The signals appear in a range of 7, 24 to 1.87 ppm. In low fields, the first signal that appears is at 7.24 ppm with an integration of four protons, these correspond to the protons of the aromatic ring (Ar). The signals at 6.04 and 5.52 ppm, come from the vinyl protons that are located at each end of the molecule, these signals have, in total, an integration for four protons. At 4.49 ppm, a multiple signal appears that is integrating for four protons, this signal comes from the protons of the methylene group located between oxygen and the aromatic ring (Ar-CH ₂ -0-). At 4.20 ppm a multiple signal is located that is integrated for four protons, the signal comes from the protons of the methylene group that is located next to the oxygen coming from methacrylic acid (CH-CH ₂ -0). The multiple signal that is located at 4.01 ppm, with an integration of two protons, belongs to the proton of the methine group that contains this molecule (-CH-). The signal at 3.52 ppm represents the protons of the methylene group that are between oxygen and the methine group of the molecule (0-CH ₂ -CH), said signal is composed of four protons. Finally, the signal observed in a chemical shift of 1.87 ppm is composed of six protons and represents the protons of the methyl group (-CH ₃ ).

In the ¹³ C NMR spectrum for this same compound, ten signals in the range of 167.4 to 18.3 ppm can be observed, which correspond to those expected for the synthesized compound. In high fields, the first signal observed at 167.4 ppm corresponds to carbon of the carbonyl group from methacrylic acid (-C = 0). The signal located at 137.3 ppm corresponds to the carbon of the aromatic ring attached to the methylene group (B). The signal located at 135.9 ppm is assigned to the quaternary carbon of the vinyl bond (C = CH ₂ ). A signal from the central carbons of the aromatic ring (A) appears in a chemical shift of 127.9 ppm. At 126.0 ppm the signal corresponding to the carbon of the unsaturated methylene group of the molecule is found (C = CH ₂ ). The signal presented at 73.2 ppm is assigned to the carbon of the methylene group located between the aromatic ring and oxygen (Ar-CH ₂ -0). The signal at 70.9 ppm is assigned to the carbon of the methylene group that is located between oxygen and the methine group of this molecule (0-CH ₂ -CH-). In a chemical displacement of 68.9 ppm, the signal from the methine group that possesses this monomer (-CH-) is located. The signal that is located at 65.7 ppm is assigned to the carbon of the methylene group that is next to oxygen that comes from methacrylic acid (-CH ₂ -0-). Finally, the signal that is in a chemical shift of 18.3 ppm, represents the carbon of the methyl group (-CH ₃ ) that possesses this monomer.

Characterization of compound l, 4-bis (oxirane-2-lmethox!) Butane [BE-1,4-OH].

 The bifunctional monomer from 1,4-butanediol is obtained in a synthetic route consisting of 2 steps. The first of these consists in obtaining the intermediate compound 1,4-bis (oxyran-2-ylmethoxy) butane [BE-1,4-OH].

Physical Properties

BE-1,4-0H is a light yellow liquid with a molecular weight of 202.25 g / mol, soluble in acetone, chloroform and dichloromethane. The yield obtained for this compound was 54%.

Elemental Analysis

The composition and purity of compound BE-1,4-0H was obtained by elemental analysis technique. The values obtained through this technique are observed in Table 10. The values coincide with the values calculated for the expected compound. From these results, it can be established that the purity of the compound is 97.3%.

Table 10 Elemental Analysis for compound BE-l, 4-OH

 Element%%

 Experimental Calculated

C 59.37 57.78

Or 31.65 34.09 *

H 8.98 8.13 Infrared Spectroscopy Analysis

The IR-FT spectrum of compound BE-1,4-0H is shown in Figure 14. In this spectrum, it is possible to observe some bands that give evidence of the formation of the compound, said absorption bands are: in 1254, 1204 and 1107 cm ^"1 are located absorption bands that correspond to the symmetric O _sim and asymmetric O _{as im} elongation modes of the COC link. Likewise, the vibration of the skeleton of the epoxy ring is represented by the band that appears at 856 cm ^"1 . On the other hand, there is more evidence with the absence of the band that corresponds to the stretching of the υΟ-Η bond present in the raw material, which normally appears between 3200 and 3600 cm ^"1 .

NMR spectroscopy of ^ and ¹³ C

The NMR spectrum of the intermediate compound BE-1,4-0H is presented in Figure 15. In it, a total of seven signals can be observed that integrate for eighteen protons, corresponding to the expected compound. The signals range between 3.7 and 1.6 ppm. The signals at 3.72 and 3.38 ppm that integrate for two protons each, are assigned to the methylene protons located between the oxygen and the epoxide ring (-0- CH ₂ -). The multiple signal located at 3.52 ppm, which integrates for four protons, corresponds to the methylene protons located next to the oxygen in the center of the molecule (-0-CH ₂ -CH ₂ -). The signal found at 3.16 ppm, integrates for two protons and corresponds to the proton of the methine in the epoxide ring. The signals found at 2.81 and 2.62 ppm, integrate for a total of four protons and correspond to the methylene protons located in the epoxide ring. Finally, in higher fields, a multiple signal is found at 1.6 ppm, which gives an integration of four protons, this is assigned to the protons of the methylenes that are in the center of the hydrocarbon chain (O-CH ₂ -CH ₂ -CH ₂ -CH ₂ -0). Figure 16 shows the C-NMR spectrum of intermediate compound BE-1,4-0H. In this spectrum, only five different signals are presented due to the symmetry of the molecule; same that correspond to the expected signals for this compound. The range in which they appear ranges from 71.4 to 26.3 ppm. In low fields, the signals that appear at 71.4 and 71.2 ppm are assigned to the carbons of the methylene-bound oxygen of the ether functional group (-CH ₂ -0-CH ₂ -). The signal at 50.8 ppm, is assigned to the methine carbon of the epoxy ring. The signal found at 44.2 ppm is assigned to the methylene carbon of the epoxy ring. Finally, in high fields, a signal appears at 26.3 ppm, which is assigned to the carbons of the methylene found in the center of the molecule (-0-CH ₂ -CH ₂ -_CH ₂ -CH ₂ - 0-).

Characterization of compound 1, 4-bis [2-hydroxy-3-methacryloxy propoxy] butane [MB-1, 4-OH].

Physical Properties

The compound MB-1,4-0H is a light yellow liquid, with a molecular weight of 374.43 g / mol. It is soluble in acetone, chloroform and dichloromethane. The yield for the second stage of synthesis is 67%. The monomer, finally, was obtained with a total yield of 60.5%.

Elemental Analysis

The composition and purity of compound MB-1,4-0H was obtained through the elemental analysis technique. Table 11 shows the values obtained.

Table 11 Elemental Analysis for compound MB-l, 4-OH

 Element%%

Experimental Calculated c 57.74 56.81

Or 34, 18 * 34.91 *

H 8.08 8.28

From the results obtained, it can be established that the purity of the compound is 98.3%.

Infrared Spectroscopy Analysis

Figure 17 shows the IR-FT spectrum for compound MB-1,4-OH. The bands present in this spectrum that give evidence of the formation of the compound are: the signal that can be observed in 3444 cm ^"1 , corresponds to the stretching of the υΟ-Η bond that appears in this molecule, the band that is located at 2928 cm ^"1 corresponds to the stretching of the OC-H link, the bands located at 1637 and 815 cm ^{" 1} , which correspond to the stretching and torsion of the C = C link respectively. Likewise, a signal appears at 1718 cm ^"1 , corresponds to link stretching

0. Finally, the absence of the signal at 910 cm ^"1 , which corresponds to the vibration of the skeleton of the epoxy ring present in the intermediate compound, confirms the formation of the expected compound.

NMR Spectroscopy of ^ and ¹³ C

Figure 18 shows the NMR spectrum of the MB-1,4-0H monomer. In it eight different signals can be observed that integrate for a total of thirty protons, corresponding to the expected compound. The signals range in 6, 14 to 1.66 ppm. In low fields, the signals that are presented at 6, 14 and 5.60 ppm, integrating for each two protons, are assigned to the two different olefinic protons at the terminal end of the CH ₂ = C molecule. The multiple signal that is at 4.22 ppm, integrates for a total of four protons, and corresponds to the protons of the methylene group attached to the oxygen derived from methacrylic acid (0-CH ₂ -CH-). The multiple signal observed at 4.04 ppm and which integrates for two protons, is assigned to the proton of the methine group that is present in this molecule (OH-CH-). The multiple signal observed at 3.51 ppm integrates for eight protons, and is assigned to the protons of the methylene groups located on each side of the ether functional group (-CH ₂ -0-CH ₂ -). The multiple signal at 2.84 ppm integrates for two protons and corresponds to the proton of the hydroxyl group (-OH). Towards high fields, the simple signal presented at 1.95 ppm that integrates for six protons corresponds to the protons of the methyl group (-CH ₃ ). Finally, the signal presented at 1.66 ppm is composed of four protons, which correspond to the protons of the methylene located in the center of the alkyl chain (-CH ₂ -CH ₂ -).

The ¹³ C NMR spectrum for compound MB-1,4-0H can be seen in Figure 19. It shows nine signals that correspond to the expected compound. The displacement of the signals is located in the range of 167.3 to 18.3 ppm. The signal observed at 167.3 ppm corresponds to carbon of the carbonyl group from methacrylic acid (-C = 0). The signal presented at 135.9 ppm corresponds to the quaternary carbon of the methacrylate group (CH ₂ = C). The signal at 125.9 ppm is assigned to vinyl carbon at the terminal ends of the chain (CH ₂ = C-). The signals that can be observed at 71.5 and 71.2 ppm correspond to the two carbons attached to the ether functional group (-CH ₂ -0-CH ₂ -). The signal at 68.7 ppm corresponds to the methyl carbon that is bound to the alcohol (-CH-OH). The 65.6 ppm signal is assigned to the carbon of the methylene group attached to the oxygen from methacrylic acid (0-CH ₂ -CH). The signal that appears at 26.2 ppm is assigned to the carbons of the methylene groups that are in the center of the alkyl chain (-CH ₂ -CH ₂ ). Finally, the signal observed at 18.3 ppm corresponds to the carbon of the methyl group at the ends of the chain (-CH ₃ ). Characterization of the compound (Z) -l, 4-bis (oxiran-2-lmethox¡) -2-butene [BE-Cis-OH].

 As previously described, for the synthesis of this monomer it was necessary to prepare an intermediate compound (Z) -l, 4- bis (oxirane-2-lmethox!) 2-butene, hereinafter referred to as BE- Cis-OH.

Physical Properties

 The compound BE-Cis-OH was a light yellow liquid with a molecular weight of 200.23 g / mol. It is soluble in acetone, chloroform, dichloromethane, ethanol, and methanol. The yield with which this compound was obtained was 47%.

Elemental Analysis

 The composition and purity of the BE-Cis-OH compound was obtained by elemental analysis technique. Table 12 shows the values obtained by this technique. From the results obtained, it can be established that the purity of the compound is 92%.

Table 12 Elemental Analysis for the BE-Cis-OH compound

 Element%%

 Experimental Calculated

C 59.98 55.02

Or 31.97 * 33.66 *

H 8.05 11.32

Infrared Spectroscopy Analysis

The Be-Cis-OH compound was characterized by the infrared spectroscopy technique with Fourier transform, the spectrum obtained by this characterization technique is shown in figure 20. This spectrum allows us to confirm the formation of the compound due to the presence of the following bands: first, the absorption bands in 1254, 1095 and 1011 cm ^"1 correspond to the vibration modes of symmetrical elongation O _sim and asymmetric O _{as im} of the COC bond that forms in the epoxy compound when etherifying the alcohol present in the reagent. Similarly, the vibration of the skeleton of the epoxy ring represented by the band which appears in 761 cm ^"1 confirms the presence of this functional group in the molecule. On the other hand, it is necessary to note that the absence of the band corresponding to the stretching of the υΟ-Η bond present in the raw material, allows confirming the double replacement of the starting alcohol.

NMR Spectroscopy of ^ and ¹³ C

In the NMR spectrum of the intermediate compound BE-Cis-OH, shown in Figure 21, seven signals are presented that integrate for sixteen protons, a number that corresponds to the expected compound. The signals are in the range of 5.74 to 2.61 ppm. The multiple signal at 5.74 ppm, which integrates for two protons, is assigned to the olefinic protons that are in the center of the molecule (-CH = CH-). The double signal at 4.13 ppm is composed of four protons and corresponds to the protons of the saturated methylenes attached to the metins of the center of the molecule (-CH ₂ -CH = CH-CH ₂ ).

 The multiple signals at 3.38 and 3.75 ppm, which integrate for two protons each, correspond to the saturated methylene located between the oxygen and the epoxy skeleton. The signal at 3.16 ppm is being integrated for a total of two protons, and is assigned to the methodic protons located within the epoxy ring. Finally, the multiple signals at 2.81 and 2.61 ppm, which integrate for 2 protons each, are assigned to the methylene protons within the epoxide ring.

The ¹³ C NMR spectrum corresponding to this compound is shown in Figure 22. Five signals can be observed in it. they fall within the range of 129.4 to 44.3 ppm. The signal presented at 129.4 ppm corresponds to the olefinic carbon of the center of the molecule (-CH = CH-). The signal located at 67.0 ppm belongs to the carbon of the methylene group located between oxygen and the epoxy ring. The signal at 71.0 ppm is assigned to the methylene group that locates between oxygen and unsaturated methine in the center of the molecule (= CH-CH ₂ -0-). Towards high fields, the signal presented in 50.9 ppm belongs to the carbon of the methine group that is located within the epoxide skeleton, while the signal at 44.3 ppm corresponds to the methylene group of the same epoxide.

Characterization of compound (Z) -l, 4-bis [2-hydroxy-3-methacryloxypropoxy] -2-butene [MB-Cis-OH].

 Physical Properties

 The MB-Cis-OH compound is presented as a light yellow liquid with a molecular weight of 372.41 g / mol soluble in ethanol, acetone, DMF, chloroform and dichloromethane. The yield for the second stage of synthesis is 66%, which gives us a final yield of 56.5%.

Elemental Analysis

 The composition and purity of the MB-Cis-OH compound was determined through the Elemental Analysis characterization technique. According to the results obtained, which are shown in Table 13, the purity with which the compound was obtained was 97.8%.

Table 13 Elemental Analysis for compound MB-Cis-OH

 Element%%

 Experimental Calculated

C 58.05 56.80

Or 34.37 35.43 *

H 7.58 7.77 Infrared Spectroscopy Analysis

Figure 23 shows the IR-FT spectrum for the compound MB-Cis-OH. In this spectrum, some bands of importance can be observed that give evidence of the formation of the expected compound: the signal that is presented at a wave number of 3441 cm ^"1 , corresponds to the stretching of the υΟ-Η bond present in this molecule; absorption band that is located at 2928 cm ^"1 corresponds to the asymmetric stretching of the OC-H link, at a wave number of 1637 and 815 cm ^{" 1} , bands are located that correspond to the stretching and torsion of the link

respectively. Similarly, at 1718 cm ^"1 , a signal corresponding to the stretch of the link is located

0. A band can be observed at a wavelength of 1455 cm ^"1 , which corresponds to symmetric torsion within the plane of the 5CH ₂ link. - The absence of the signal at a wave number of 910 cm ^{" 1} , which corresponds to the vibration of the skeleton of the epoxy ring, it can also confirm the formation of the expected compound.

NMR Spectroscopy of ^ and ¹³ C

The NMR spectrum for this compound is presented in Figure 24. In the spectrum seven signals are seen that integrate for a total of twenty-eight protons, which correspond to the expected compound. The signals are in the range of 6, 14 to 1.92 ppm. The signals at 6, 14 and 5.71 ppm integrate for a total of four protons, these correspond to the two vinyl protons of the terminal unsaturated methylene (CH ₂ = CH). The signal at 5.57 ppm that integrates for 2 protons, comes from the olefinic protons that are in the center of the chain (-CH = CH-). The multiple signal at 4.22 ppm that integrates for four protons, corresponds to the protons of the methylene group located next to the oxygen that comes from methacrylic acid (-CH ₂ -0-). The multiple signal at 4.11 ppm is composed of four protons, corresponding to the methylene groups located between oxygen and the vinyl group (= CH-CH ₂ -0-). The multiple signal at 4.05 ppm that integrates for two protons corresponds to the saturated methine that is presented in this monomer. The signal that appears at a displacement of 3.68 ppm is composed of two protons, which correspond to the proton of the hydroxyl group (-OH). The multiple signals at 3.52 and 3.45 ppm that integrate for four protons are assigned to the protons of the methylene group located between the oxygen and the methine of this molecule (-0-CH ₂ -CH). Finally, the simple signal located at 1.92 ppm that integrates for six protons, is assigned to the protons of the methyl group present in the chain (-CH ₃ ).

The ¹³ C NMR spectrum for this compound can be seen in Figure 24. In it, nine signals in the range of 167.4 to 18.3 ppm can be observed that correspond to those expected for the synthesized compound. The signal presented at 167.4 ppm corresponds to the carbonyl group carbon from methacrylic acid (-C = 0). The 135.9 ppm signal is assigned to the vinyl quaternary carbon at the end of the molecule (-C = CH ₂ ). The signal presented at a displacement of 129.3 ppm corresponds to the olefinic carbon of the center of the chain (-CH = CH-). A signal corresponding to unsaturated methylene located at the end of the molecule is found at 126.0 ppm (-C = CH ₂ ). At a displacement of 71.2 ppm, a signal corresponding to the carbon of the methylene group located next to the vinyl group in the center of the chain is observed (= CH-CH ₂ ). At 68.8 ppm a signal appears corresponding to the carbon of the saturated methine group (-CH ₂ -CH-CH ₂ ). In a displacement of 66.9 ppm, the signal that comes from the carbon of the methylene group located next to the oxygen from methacrylic acid (-CH ₂ -0) is located. At 65.7 ppm there is a signal that corresponds to the methylene located between oxygen and saturated methine of this molecule (0-CH ₂ -CH-). Finally, the signal located at 18.3 ppm corresponds to the carbon of the methyl group (-CH ₃ ).

Characterization of compound l, 7-bis (ox¡rano-2-lmethoxy) heptane [BE-1,7-OH].

The MB-1, 7-OH monomer was synthesized in a two stage reaction. In the first one, the intermediate compound BE-l, 7-OH was synthesized and purified. Physical Properties

The intermediate compound BE-l, 7-OH is a light yellow liquid with a molecular weight of 244.33 g / mol, soluble in DMF, ethyl acetate, dichloromethane, chloroform and ethanol. The yield with which this compound was obtained was 37.5%.

Elemental Analysis

 The composition and purity of the compound BE-l, 7-OH was obtained through the elemental analysis technique. The values obtained by this technique are shown in Table 14. From the results obtained, it can be established that the purity of the compound is 96.5%.

Table 14 Elemental Analysis for compound BE-l, 7-OH

 Element%%

 Calculated Experimental c 63.91 61.71 or 26, 19 * 27.95 *

H 9.9 10.34

Infrared Spectroscopy Analysis

The IR-FT spectrum of the compound BE-l, 7-OH is presented in Figure 26. The bands that give evidence of the formation of the compound are: the bands in 1261, 1096 and 1021 cm ^"1 that correspond to the mode of symmetric and asymmetric elongation of the OC-OC bond Likewise, the vibration of the skeleton of the epoxy ring is represented by the band that appears at 808 cm ^"1 . Also, we have one more evidence with the absence of the band that corresponds to the stretching of the υΟ-Η bond present in the raw material, and that normally appears between 3200 and 3600 cm ^"1 .

NMR Spectroscopy of ^ and ¹³ C Figure 27 represents the ¹ H NMR spectrum of said compound, in which there are seven signals that integrate for twenty-four protons, corresponding to the expected molecule. The signals are observed in the range of 3.71 to 1.33 ppm. The multiple signals that occur at 3.71 and 3.37 ppm that integrate for a total of four protons, are assigned to the protons of the methylene group located between the epoxide and the oxygen. The multiple signal present at 3.49 ppm, which integrates for four protons, corresponds to the methylene protons in the center of the alkyl chain located next to the oxygen (-0-CH ₂ -CH ₂ -). The signal located at 3, 14 ppm, integrates for two protons, and is assigned to the proton of the methine in the epoxide. The signals that appear at 2.79 and 2.61 ppm integrate for a total of four protons and are assigned to the methylene protons located in the epoxide. Towards high fields, we found two signals, at 1.59 and 1.33 ppm that integrate for a total of ten protons, being assigned to the methylene protons that are located in the center of the alkyl chain (-CH ₂ -CH ₂ -CH ₂ -CH ₂ -CH ₂ -).

The ¹³ C NMR spectrum of this intermediate compound is shown in Figure 28. It shows seven different signals in the range of 71.56 and 26.0 ppm, these signals correspond to the expected compound. The two signals presented at 71.6 and 71.4 ppm are assigned to the two carbons attached to oxygen (-CH ₂ -0-CH ₂ ;). The signal that is presented at 50.8 ppm is attributed to the methoxy carbon of the epoxide. The signal that appears at 44.3 ppm corresponds to the epoxy methylene carbon. The signals found at 29.6 and 29.9 ppm correspond to the 4 carbons of the methylenes located in the center of the chain (-CH ₂ -CH ₂ - CH ₂ -CH ₂ -CH ₂ -CH ₂ - CH ₂ -). Finally, the signal that we can observe at 26.0 ppm corresponds to the methylene carbon located exactly in the center of the molecule's hydrocarbon chain (-CH ₂ -CH ₂ -CH ₂ -).

Characterization of the compound (l, 7-bis [2-hydroxy-3-methacryloxypropoxy] heptane [MB-l, 7-OH].

Physical Properties The bifunctional monomer MF-l, 7-OH is an amber liquid with a molecular weight of 416.51 g / mol. The yield for this second stage was 87.08%, giving a final yield for this monomer of 62.25%.

Elemental Analysis

 The compound MB-l, 7-OH was characterized by the Elemental Analysis technique to obtain its composition and purity. The results of this test are shown in Table 15. According to these, the bifunctional monomer was synthesized with a purity of 96%.

Table 15 Elemental Analysis for compound MB-l, 7-OH

 Element%%

 Experimental Calculated

C 60.56 58.34

Or 30.73 * 30.3 *

H 8.71 11.36

Infrared Spectroscopy Analysis

The IR-FT spectrum for the MB-Cis-OH monomer is shown in Figure 29. This spectrum allows us to observe some bands that give evidence of the formation of the expected compound: the signal that is presented at a wavelength of 3458 cm ^"1 , is due to the stretching of the υΟ-Η link; a signal corresponding to the asymmetric stretching of the uC-H link is located at a wave number of 2858 cm ^{" 1} . The presence of the double terminal links is evidenced by the bands that are located at a wave number of 1634 and 814 cm ^"1 , which correspond to the stretching and torsion of the link

respectively. Finally, in 1711 cm ^"1 , the signal corresponding to the stretching of the link is presented

The Absence of the signal at a wavelength of 910 cm ¹ , which corresponds to the vibration of the epoxy ring skeleton, can confirm the complete functionalization of this group and the correct insertion of methacrylate groups into the final compound.

NMR Spectroscopy Analysis of H and ¹³ C

The H NMR spectrum for this compound is presented in Figure 30. In it we can see the presence of ten signals, whose integration corresponds to a total of thirty-six protons, corresponding to the expected compound. All signals are presented in a range of 6.14 to 1.2 ppm. In low fields, the first two signals at 6.14 and 5.59 ppm correspond to the two olefinic protons at the end of the chain (CH ₂ = C-). Multiple signals that appear in 4.22 integrate for a total of two protons, and are assigned to the protons of the methine group. The triple signal that appears at 3.87 ppm, and which integrates for two protons, corresponds to the methine protons attached to the pending hydroxyl group (- CH ₂ -CH-CH ₂ -). Towards high fields, there is a multiple signal at 3.68 ppm that integrates for two protons and is assigned to the protons of the hydroxyl group (-OH). The multiple signal that appears at 3.52 ppm is composed of a total of eight protons, which are assigned to the methylene protons that are on each side of the oxygen (-CH ₂ -0-CH ₂ -). The simple signal that is located at 1.96 ppm integrates for six protons, and is assigned to the methyl protons from methacrylic acid (-CH ₃ ). The multiple signal at 1.56 ppm is being integrated for four protons, which correspond to the methylene protons in the center of the hydrocarbon chain (C). The signal at 1.32 ppm is integrated for four protons, and these come from the methylene located on both sides of the methylene in the center of the chain (-CH ₂ -CH ₂ -CH ₂ ). Finally, the signal at 1.25 ppm is composed of two protons, which correspond to the methylene group that is exactly at the center of the hydrocarbon chain of the molecule (A). The ¹³ C NMR spectrum for this monomer is presented in Figure 31. In said spectrum a total of eleven signals can be located in a range of 167.2 to 17.9 ppm, which correspond to those expected for the synthesized compound. Towards low fields, the signal that occurs in a chemical shift of 167.1 ppm corresponds to the carbonyl group from methacrylic acid (-C = 0). At a chemical shift of 135.8 ppm, the signal that comes from the quaternary carbon of the monomer terminal vinyl bond is located (C = CH ₂ ). The signal that is located at a displacement of 125.8 ppm corresponds to the carbon of the unsaturated methylene group that is located at the terminal end of the monomer (C = CH ₂ ). Towards high fields, the signals located at 71.6 and 71.4 ppm belong to the methylenes attached to the ether functional group (-CH ₂ -0-CH ₂ -). The signal that is located in a displacement of 68.5 ppm belongs to the carbon of the methine group present in the bifunctional monomer (-CH ₂ -CH-CH ₂ -). At a chemical shift of 65.8 ppm, a signal corresponding to the methylene group attached to the oxygen coming from methacrylic acid (-CH-CH ₂ -0) is presented. The signal at 29.2 ppm corresponds to the saturated methylene groups located in the center of the molecule (carbons B and C). At a chemical displacement of 25.9, a signal is presented that comes from saturated methylene that is located exactly in the center of the bifunctional compound (carbon A). Finally, the signal presented at 17.9 ppm corresponds to the carbon of the methyl group located at the terminal ends of this compound (CH ₃ -).

Preparation of composite materials.

Four photopolymerizable composite materials were prepared manually using different organic matrices based on Bis-GMA, using as diluents a mixture of TEGDMA with the monomers MB-Fen-OH, MB-Cis-OH and MB-l, 7-OH . The photoinitiator system used was composed of the ethyl camphorquinone / 4-dimethylaminobenzoate pair; both in a percentage of 0.5% of weight. As filler material, silanized silicon oxide particles of nanometric size were used in a percentage of 40% by weight with with respect to the total composite material. Table 16 shows the composition of the organic matrix of the different composites produced.

Table 16 Composition of the organic matrix of the composites evaluated

Material Monomer Monomer Monomer

 1 2 3

 (%) (%) (%)

 MY Bis-GMA TEGDMA

 (65%) (35%)

 M2 Bis-GMA TEGDMA MB-Fen-OH

 (65%) (20%) (15%)

 M3 Bis-GMA TEGDMA MB-Cis-OH

 (65%) (20%) (15%)

 M4 Bis-GMA TEGDMA MB-l, 7-OH

 (65%) (20%) (15%)

Assessment of flexural strength and flexural modulus

The flexural strength of the prepared composite materials was evaluated based on the provisions of section 7.11 of the International Standard ISO-4049 Dentistry-Polymer-based filling, restorative and luting materials (105), while the flexural modulus was evaluated according to what is established in specification no. 27 ANSI / ADA (106).

The specimens were irradiated with an intensity of 460 mW / mm ² . The specimens were kept in distilled water at 37 ° C until the time of the test.

The arithmetic mean and standard deviation for the Flexural Resistance (MPa) values of each of the groups evaluated is shown in Table 17, while Table 8 presents the values obtained for the Flexural Module (MPa). Table 17 Arithmetic Mean and Standard Deviation for Flexural Strength (MPa) values of composite materials

Medium Deviation Group N

 typical

 MI 52.33 5.39 3

 M2 65.30 6.30 3

 M3 51.96 2.76 3

 M4 49.44 4.31 3

 Total 54.75 7.69 12

Table 18 Arithmetic Mean and Standard Deviation for the Flexural Modulus (MPa) values of composite materials

Medium Deviation Group N

 typical

 MI 4949.72 274.85 3

 M2 5717.81 172.07 3

 M3 4969.53 147.94 3

 M4 4390.46 231.94 3

 Total 5006.88 524.99 12

A posthoc test is performed, and the results are presented in tables 19 and 20 for resistance and flexural modulus respectively.

Table 19 Table of homogeneous subsets for Flexural Strength (MPa) of materials

Material N Subset

 1 2

 M4 3 49.44

M3 3 51.96 MI 3 52.33

 M2 3 65.30

 Sig. 0.884 1.000

Table 20 Table of homogeneous subsets for the Flexural Module (MPa) of the materials

Material N

 Subset

 1 2 3

 M4 3 4390.46

 MI 3 4949.72

 M3 3 4969.52

 M2 3 5717.80

 Sig. 1.00 0.999 1,000

The results of the multiple comparison test performed for the flexural strength of these materials, allows to determine that the property decreases, in a decreasing manner, as follows: M2> M3 = M1 = M4. While for the flexural modulus, the decreasing order for the materials is as follows: M2> M1 = M3> M4.

For both flexural properties, it is important to note that the material called M2, presents statistically significant differences to the rest, achieving better properties compared to the control resin. The organic matrix composition contains the MB-Fen-OH monomer in a percentage of 15% by weight with respect to the entire organic component of the composite. The reason that can explain the significant increase in the values of the flexural properties is due to the presence of an aromatic ring in the monomer, which reinforces the polymer structure of the Bis-GMA / TEGDMA pair. In the case of Flexural Strength, the rest of the materials MI, M3 and M4 do not present significant differences between them. The composition of the materials MI and M4 has, in addition to the Bis-GMA / TEGDMA pair, the monomers MB-Cis-OH and MB-l, 7-OH respectively; both monomers, being linear, do not provide greater resistance to the polymeric structure when compared to the resin used as the M3 control group.

Finally, for the Flexion Module, the material that presented the lowest statistically speaking value was called M4. This material contains the MB-1, 7-OH monomer within its composition. Analyzing the structure of the compound, the presence of a seven-carbon hydrocarbon chain in the center of the molecule can be observed, this characteristic, makes the resulting polymer have a lot of flexibility, and therefore contributes to obtain a lower flexural modulus when compared with the resin used as a control.

Conversion Degree Determination

To assess the degree of conversion of the materials an Infrared Spectrometer with Fourier Transformer Perkin Elmer FT-IR System 2000 was used. An infrared spectrum was obtained from the materials before and after polymerization. In each of the spectra obtained, the height of the absorption band of the aliphatic C = C bond at 1638 cm ^"1 , and of the absorption band of the aromatic C = C bond located at 1609 cm ^{" 1 were determined} . The aromatic C = C bond vibration was used as internal reference. The monomer conversion percentage was determined according to the following equation:

Conversion Degree (* one -

Table 21 shows the arithmetic averages and standard deviations for the degree of conversion values of each of the materials evaluated. Table 21 Arithmetic Mean and Standard Deviation for the Conversion Degree values of composite materials

Medium Deviation Group N

 typical

 MI 70.26 0.17 3

 M2 74.19 0.03 3

 M3 69.36 2.47 3

 M4 67.92 0.87 3

 Total 70.43 2.67 12

The post-hoc test was performed to determine between which groups these differences exist, the results are shown in Table 22.

Table 22. Table of homogeneous subsets for the Degree of Conversion of materials

Material N Subset

 1 2

 M4 3 67.92

 M3 3 69.36

 MI 3 70.26

 M2 3 74.19

 Sig. 0.884 1.000

According to the results of the multiple comparison test performed for the degree of conversion, this property decreases, in a decreasing manner, as follows: M2> M3 = M1 = M4.

Accordingly, material M2, presents values of degree of conversion significantly higher than the rest of the materials evaluated. This characteristic can justify the fact that this material presented the best mechanical properties, since according to several authors, There is a clear linear relationship between the degree of conversion, and the flexural properties of the materials.

Conclusions

 Mixtures of the monomers synthesized with BisGMA and TEGDMA allow the incorporation of 40% by weight of silanized nanometric size silicon oxide to make easily handled composite resins. Other publications concerning the manual preparation of composite resins with experimental monomers, report that the percentage of inorganic filler used ranges between 40 and 50%. For a commercial resin, and according to the manufacturer's specifications, the percentage by weight of inorganic content varies between 70 and 80%.

The composite materials made in the present invention, using the experimental monomers MB-Cis-OH and MB-l, 7-OH have mechanical properties similar to those observed in composite resins that use only BisGMA / TEGDMA as components of the organic matrix. That is, the new composite resins can be used for direct restoration of teeth, since they have the same mechanical properties as a conventional composite resin. In addition, since the reported monomers have a higher molecular weight than TEGDMA, the contraction is expected to be less than that of commercial resins.

The material containing the experimental monomer MB-Fen-OH has significantly greater mechanical properties than those presented by composite resins that use only BisGMA / TEGDMA as the organic matrix. This characteristic makes it a commercially competitive resin with the resins that are currently marketed.

Therefore, the liquid monomers described in the present invention can be used for the formulation of composite resins for direct dental use, improving the mechanical properties of commercial resins and therefore, increasing their strength and durability. References

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Claims

 1.- A bis-glycidylmethacrylate monomer, characterized by the formula (I)

where R can be

a biphenyl radical unsubstituted or substituted by OH, oxygen, amino, or C1-C4 alkyl, carbonyl or carboxyl; a phenyl group substituted by OH, oxygen, amino, Cl-3 alkyl, carbonyl or carboxyl; a C2-10 alkyl group unsubstituted or substituted by hydroxyl, oxygen, amino, C1-C4 alkyl, carbonyl or carboxyl; a C2-C10 alkenyl group unsubstituted or substituted by hydroxyl, amino, oxygen, C1-C4 alkyl, carbonyl or carboxyl;

2. - A monomer according to claim 1, characterized in that

R is selected from biphenyl, 1,4-dimethyl-phenyl, C4-C7 alkyl, C2-C4 alkenyl.

3. - A monomer according to claim 1, characterized in that it is 4,4'-bis [2-hydroxy-3-methacryloxypropoxy] biphenyl of formula MB-4,4-0H

4. A monomer according to claim 1, characterized in that it is 1, 4-bis [(2-hydroxy-3-methacryloxypropoxy) methyl] phenyl of formula MB-Fen-OH

5. A monomer according to claim 1, characterized in that it is

6. - A monomer according to claim 1, characterized in that it is

7. - A monomer according to claim 1, characterized in that it is

 ? · <¾;. · · J-OH

8.- A method for obtaining the monomer of the general formula (I), characterized in that it comprises the steps of: a) reacting a compound of the general formula OH-R-OH with epichlorohydrin to give an intermediate compound in the presence of a solvent and b) reacting the intermediate compound obtained from step a) with methacrylic acid in the presence of a solvent and a catalyst to give the compound of general formula (I) according to the following reaction scheme:

wherein R has the meanings indicated in claim 1.

9. A method for obtaining the 4,4'-bis [2-hydroxy-3-methacryloxypropoxy] biphenyl monomer according to claim 3, characterized in that it comprises the steps of: a) reacting a compound of 4, 4-bisphenol with epichlorohydrin in the presence of a solvent to obtain the intermediate compound of formula BE-4,4-0H

Y

b) reacting the intermediate compound with methacrylic acid in the presence of a solvent to obtain the compound 4,4'-bis [2-hydroxy-3-methacryloxypropoxy] biphenyl of formula MB-4,4-0H:

10. The method for obtaining the 4,4'-bis [2-hydroxy-3-methacryloxypropoxy] biphenyl monomer according to claim 9, characterized in that in step a) a compound of 4.4 is reacted -bisphenol with epichlorohydrin in the presence of dimethylformamide as solvent and potassium carbonate to obtain the intermediate compound BE-4,4-0H and in step b) said intermediate compound BE-4,4-0H is reacted with methacrylic acid in relation stoichiometric in the presence of dimethylformamide as solvent and triethanolamine to give the compound 4,4'-bis [2-hydroxy-3-methacryloxypropoxy] biphenyl (MB-4,4-0H) according to the following reaction scheme:

11. A method for obtaining the 4,4'-bis [2-hydroxy-3-methacryloxypropoxy] biphenyl monomer of formula MB-4,4-0H according to claim 3, characterized in that it comprises the step of making Reacting the 4,4-biphenol compound with the glycidyl methacrylate in the presence of a solvent to obtain the 4,4'-bis [2-hydroxy-3-methacryloxypropoxy] biphenyl compound of formula MB-4,4-0H:

12. The method for obtaining the 4,4'-bis [2-hydroxy-3-methacryloxypropoxy] biphenyl monomer according to claim 11, characterized in that the 4,4-biphenol compound is reacted with the glycidylmethacrylate in a stoichiometric ratio of 1: 2.5, using triethylamine and hydroquinone as inhibitor and dimethylformamide as solvent according to the following reaction scheme:

13. A method for obtaining the l, 4-bis [(2-hydroxy-3-methacryloxypropoxy) methyl] phenyl monomer of formula MB-Fen-OH according to claim 4, characterized in that it comprises the steps of a ) reacting 1,4-benzenedimethanol and epichlorohydrin in the presence of a solvent to give the intermediate compound BE-Fen-OH of the formula:

 BE-Fen-OH b) reacting said BE-Fen-OH intermediate compound with methacrylic acid in the presence of a solvent to obtain the 1,4-bis [(2-hydroxy-3-methacryloxypropoxy) methyl] phenyl compound of formula MB -Fen-OH:

14. A method for obtaining the l, 4-bis [(2-hydroxy-3-methacryloxypropoxy) methyl] phenyl monomer of formula MB-Fen-OH according to claim 13, characterized in that it comprises the steps of: a) reacting the 1,4-benzenedimethanol and epichlorohydrin compound, in the presence of sodium hydride as a catalyst and DMF as a solvent to obtain the intermediate compound BE-Fen-OH and b) reacting said intermediate of formula BE-Fen-OH with methacrylic acid in the presence of dimethylformamide and triethanolamine according to the following reaction scheme:

 Step 1 step

15. A method for obtaining the monomer l, 4-bis [2-hydroxy-3-methacryloxypropoxy] butane of formula MB-1,4-0H according to claim 5, characterized in that it comprises a) reacting 1 , 4-butanediol and epichlorohydrin in the presence of a solvent to obtain the intermediate compound of formula BE-1,4-0H:

BE-1.4-OH _and b) reacting said intermediate compound BE-1,4-0H with acrylic acid in the presence of a solvent to obtain said compound of formula MB-1,4-0H

MLÍ-1.4-ÜH

16. A method for obtaining the 1, 4-bis [2-hydroxy-3-methacryloxypropoxy] butane monomer of formula MB-1,4-0H according to claim 15, characterized in that it comprises a) reacting 1 , 4-butanediol and epichlorohydrin in the presence of sodium hydride as catalyst and dimethylformamide as solvent to obtain the intermediate compound of formula BE-1,4-0H, and b) reacting said intermediate compound BE-1,4-0H with acrylic acid in a stoichiometric ratio of 1 to 2.5 in the presence of triethanolamine and dimethylformamide as solvent to obtain said compound of formula MB-1,4-0H according to the following reaction scheme

17. A method for obtaining the monomer (Z) -l, 4-bis [2-hydroxy-3-methacryloxypropoxy] -2-butene of the formula MB-Cis-OH, according to claim 6, characterized in that It comprises the steps of: a) reacting the compound cis-2-buten-l, 4-diol and epichlorohydrin in the presence of a solvent to obtain the intermediate compound of formula BE-cis-OH

Y

b) reacting said BE-Cis-OH intermediate compound with acrylic acid in the presence of a solvent to obtain the compound of formula MB-Cis-OH

 M8-Cw-Oíi

18. A method for obtaining the monomer (Z) -l, 4-bis [2-hydroxy-3-methacryloxypropoxy] -2-butene of the formula MB-Cis-OH, according to claim 17, characterized in that understand the stages of

a) reacting the compound cis-2-buten-l, 4-diol and epichlorohydrin in the presence of sodium hydride as catalyst and dimethylformamide as a solvent to obtain the intermediate compound of formula BE-cis-OH, and

b) reacting said BE-Cis-OH intermediate compound with acrylic acid in a stoichiometric ratio of 1 to 2.5 in the presence of triethanolamine as catalyst and dimethylformamide as a solvent to obtain the compound of formula MB-Cis-OH according to The following reaction scheme:

Step 1 Step 2

C

 MB-Cis-OH

19. A method for obtaining the l, 7-bis [2-hydroxy-3-methacryloxypropox!] Heptane monomer of formula MB-l, 7-OH, according to claim 7, characterized in that it comprises the steps from: a) reacting 1,7-heptanediol and epichlorohydrin in the presence of a solvent to obtain the intermediate compound of formula BE-1,7-OH

BE-1.7-OH and b) react the intermediate compound BE-l, 7-OH in the presence of a solvent and a catalyst to obtain the compound of formula MB-l, 7-OH:

20. A method for obtaining the monomer l, 7-bis [2-hydroxy-3-methacryloxypropoxy] heptane of formula MB-l, 7-OH, according to claim 7, characterized in that it comprises the steps of: a) reacting 1,7-heptanediol and epichlorohydrin in the presence of dimethylformamide as solvent and sodium hydride as catalyst to obtain the intermediate compound of formula BE-1, 7-OH and b) reacting the intermediate compound BE-1, 7- OH in the presence of dimethylformamide as solvent and triethanolamine to obtain the compound of formula MB-1, 7-OH according to the following reaction scheme:

21. - A direct dental restoration resin formulation, characterized in that it comprises at least a first bis-methacrylate monomer selected from the group consisting of Bis-GMA, TEGDMA, UDMA, Bis-EMA6, Bis-EMA, PEGMA; at least a second bis-methacrylate monomer according to claim 1, which is capable of acting as a solvent for and polymerizing with said first bis-methacrylate monomer, and a photoinitiating system.

22. - A direct dental restoration resin formulation according to claim 21, characterized in that said photoinitiator system It comprises camphorquinone and an organic amine, selected from 2-N, ethyl N'-dimethylaminomethacrylate, Ν, Ν'-dimethyl-para-toluidine and ρ-Ν, Ν'-ethyl dimethylaminobenzoate.

23. - A direct dental restoration resin formulation according to claim 21, characterized in that it also comprises between 42 and 85% by weight of a filling material.

24. - A direct dental restoration resin formulation according to claim 23, characterized in that said filling is selected from quartz, barium glass, barium glass / silica, barium glass mixture, quartz / barium glass, silica, zirconia / silica, mixture of silica, lithium aluminosilicate, sodium and / or zinc aluminosilicate and barium aluminosilicate or sol-gel derivatives of ceramic materials.

25. - A direct dental restoration resin formulation according to claim 23, characterized in that said filling is selected from dispersed nanoparticles or silicon oxide and Zirconium nanocluster having a particle size ranging from 1 to 100 nm .

26. - A direct dental restoration resin formulation according to claim 24, characterized in that said filling has a particle size ranging from 1 to 100 μηι.

27. - A direct dental restoration resin formulation according to claim 24, characterized in that said filling also comprises between 40 and 85% by weight based on the total weight of the composition of a coupling agent.

28. - A direct dental restoration resin formulation according to claim 27, characterized in that said a coupling agent is selected from [3-methacryloxypropyltrimethoxysilane (MPTMS), vinyl triethoxysilane, dimethyl dichlorosilane, hexamethylene disilazane, dimethyl polysiloxane.