KR20050071162A - Layered organoclay composite, method for preparing the same, and polyester nanocomposites prepared using the same - Google Patents

Abstract

The present invention relates to a layered organic clay compound, a method for preparing the same, and a polyester nanocomposite prepared using the same, and more particularly, to a layered clay substituted with an organic agent by mixing an organic agent including a layered clay and a reactive group. After the preparation, the present invention relates to a layered organic clay compound prepared by adding a silane compound and a method for preparing the same. The present invention also relates to a polyester nanocomposite having improved dispersibility of a clay layer prepared through a polymerization reaction of the layered organic clay compound and a polyester monomer. Polyester nanocomposite according to the present invention is excellent in thermal stability, mechanical strength and gas barrier properties can be used in the manufacture of films, containers, engineering plastics, tire cord reinforcement and the like.

Description

Layered organic clay compound, method for preparing the same, and polyester nanocomposite prepared using the same {Layered organoclay composite, method for preparing the same, and polyester nanocomposites prepared using the same}

The present invention relates to a layered organic clay compound, a method for preparing the same, and a polyester nanocomposite prepared using the same, and more particularly, to a layered clay substituted with an organic agent by mixing an organic agent including a layered clay and a reactive group. After the preparation, the present invention relates to a layered organic clay compound prepared by adding a silane compound and a method for preparing the same. The present invention also relates to a polyester nanocomposite having improved dispersibility of a clay layer prepared through a polymerization reaction of the layered organic clay compound and a polyester monomer.

Polymer nanocomposite is a new concept material that dramatically improves the thermal, mechanical and gas barrier properties of existing polymers by peeling clay minerals having a layered structure into nano-sized plate-based units and dispersing them in polymer resin.

This property improvement is due to the fact that the clay mineral has a plate-like structure, which has a large aspect ratio and a large area that can interact with the polymer. However, since the layered clay mineral is hydrophilic and does not mix well with the hydrophobic polymer and the insertion of the polymer between the layers of the clay mineral is not easy, it is not so simple to peel and disperse the layered clay into the polymer resin. Therefore, organic compounds such as alkylammonium are usually inserted between the clay layers to widen the gap between the plates to facilitate the penetration of the polymer resin to produce nanocomposites.

Methods of separating clay minerals into nano-sized plate-shaped basic units and dispersing them in polymer resin include solution method, compounding method, and polymerization method. Among them, compounding and polymerization methods have been studied in the US since the 1980s. The technology has been commercialized in Western countries, including Japan.

The solution method is a method in which an organic clay is immersed in a polymer solution so that a solvent penetrates between layers of clay to disperse the clay layers and to disperse the clay layers in the polymer resin during the drying process. However, the solution method has a very limited solvent capable of dissolving the polymer, and also has a difficulty in recovering it.

In addition, compounding is a technique of inserting and dispersing molten polymer between clay layers by mechanical mixing. While this method is easy and inexpensive to manufacture, it is difficult to disperse the clay layers in the polymer, thereby limiting the improvement of physical properties of the nanocomposite.

Meanwhile, the polymerization method is a technique of dispersing clay layers in a polymer by inserting a monomer between layers of clay minerals and performing a polymerization reaction. This method is easy to insert the monomer between the clay layer by mixing the organic clay and the monomer at the beginning of the reaction, it is possible to manufacture a nanocomposite material in which the clay layers completely peeled in the polymer.

In the production of polyester nanocomposites, first of all, a process of producing a layered organoclay by modifying the surface and interlayer properties of the layered clay with the polyester in a friendly manner is required. The production of layered organic clay by substituting inorganic cations located between layers of clay minerals with hydrophobic organic cations is the most widely used method. Organic cations intercalated between clay layers can increase the interlayers of clay to facilitate the insertion of monomers or polymers between the clay layers, as well as to improve compatibility with clay minerals and polyester resins. .

The most widely used organizing agent for producing layered organic clay is ammonium ions. Since ammonium ions are easily derived from various kinds of amines, they have the advantage that they can be prepared through simple processes or can be purchased at low prices. However, ammonium ions begin pyrolysis at about 200 ° C. and return to their original hydrophilic properties. Due to this low thermal stability, organic clays substituted with ammonium ions are not suitable for the production of nanocomposites with polyester resins requiring processing temperatures of 200 ° C or higher. In addition, the nanocomposites are discolored or decomposed during polymerization or extrusion, resulting in a deterioration in physical properties. Thus, in order to produce polyester nanocomposites requiring high processing temperatures, the preparation of layered organic clays with good thermal stability is essential.

International Publication No. 98/10012 discloses an organic clay-polymer mixture in which a molten polymer having a high melting process temperature and an organic phosphonium cation are inserted between layers of clay to melt-mix a layered organic clay exhibiting high thermal stability. International Publication No. 00/78540 and International Publication No. 00/78855 disclose that nano-layered organic clay substituted with phosphonium ions having a linear or branched alkyl group having 8 or more carbon atoms as a substituent is melt-mixed with a thermoplastic polymer. A method of making a composite is described. However, while the phosphonium ions used in the above patents have excellent thermal stability, but are composed only of aliphatic hydrocarbons, it is difficult to prepare nanocomposites by reaction with polar polymers.

Therefore, in order to manufacture nanocomposites with polymers having polar reactive groups, such as polyester resins, research on layered organic clays having high thermal stability and excellent affinity with polar polymers is required.

In order to solve the problems of the prior art, the present inventors have studied and studied to obtain a polyester nanocomposite having excellent thermal stability, mechanical strength and gas barrier properties, and as a result, a phosphonium organic agent and a silane compound having a reactive group were used. It was possible to obtain a layered organic clay compound by using, it was possible to obtain a polyester nanocomposite having excellent physical properties by using this, the present invention was completed based on this.

Accordingly, an object of the present invention is to provide a method for preparing a layered organic clay compound having excellent thermal stability and high affinity with a polyester resin, and a layered organic clay compound prepared by the above method.

Another object of the present invention is to provide a polyester nanocomposite having excellent thermal stability, mechanical strength and gas barrier properties by improving the dispersibility of the clay layer.

The method for producing a layered organic clay compound according to the present invention for achieving the above object is, by adding an organic agent containing a layered clay and a reactive group in a molar equivalent of 0.1 to 5 times the cation exchange capacity of the layered clay, Providing a layered clay substituted with; And adding and stirring the silane compound in a molar equivalent of 0.1 to 5 times the cation exchange capacity of the layered clay.

The layered organic clay compound according to the present invention for achieving the above object is prepared by the above-described manufacturing method.

In addition, the polyester nanocomposite according to the present invention for achieving the above another object is polymerized polyester monomer by adding 0.1 to 20 parts by weight of the layered organic clay compound prepared by the above-described method with respect to 100 parts by weight of polyester monomer It is made by reaction.

Hereinafter, the present invention will be described in more detail.

As described above, the present invention is prepared by mixing (a) layered clay and (b) an organic agent including a reactive group to prepare a layered clay substituted with an organic agent, and then adding (c) a silane compound.

(A) layered clay

The layered clay usable in the present invention is a natural or synthetic mineral composed of a plate-like layer having a width and length of 100 to 5,000 mu m, a thickness of 6 to 15 mm 3, and an aspect ratio of 100 to 5,000. It is preferable that the cation exchange capacity of the layered clay is 20 meq / 100 g to 200 meq / 100 g, and more preferably, a layered clay having a cation exchange capacity of 50 meq / 100 g to 150 meq / 100 g may be used.

The layered clay is at least one selected from the group consisting of montmorillonite, bentonite, hectorite, fluoride hectorite, bidelite, saponite, nontronite, vermiculite, macadamite, mica and fluorinated mica, and the like. Use montmorillonite.

(B) organic agents containing reactive groups

The organic agent comprising a reactive group according to the present invention is a phosphonium cationic salt containing at least one reactive group capable of chemical bonding with a silane compound and a polyester monomer without thermal decomposition at a temperature of 300 ° C. or higher, and is represented by the following Chemical Formula 1 .

Wherein R ₁ , R ₂ , R ₃ and R ₄ are the same as or different from each other, and are aliphatic hydrocarbons having 4 to 40 carbon atoms, and at least one of R ₁ to R ₄ is a carboxyl group, an amine group, a hydroxy group, an ester group, It is a reactive group chosen from the group which consists of an epoxy group, a silanol group, a carbonate group, and an imide group.

(C) silane compounds

The silane compound used in the present invention can chemically bond with the reactive group of the phosphonium cation salt present between the layers of the organic clay, and also connect the clay and the polyester resin by chemically bonding the polyester monomer during the polymerization reaction. It acts as a coupling agent.

The silane compound may be characterized by R-SiX ₃ . In this case, R is an organic functional group having a reactive group, X means a methoxy group or an ethoxy group that can be converted to a silanol group by hydrolysis. Representative silane compounds include vinylchlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, octadecyltrimethoxysilane, gammaaminopropyltrimethoxysilane, gammaaminopropyltriethoxysilane, N- (2-amino Ethyl) -3-aminopropyltrimethoxysilane, N- (2-vinylbenzylaminoethyl) -3-aminopropyltrimethoxysilane, N-phenyl-gammaaminopropyltrimethoxysilane, gamma glycidoxypropyl tree Methoxysilane, gamma methacryloxypropyltrimethoxysilane, gamma mercaptopropyltrimethoxysilane, gamma-aminopropylphenyldimethoxysilane, gamma propionamido trimethoxysilane, N-trimethoxysilylpropyl-N (Beta-aminoethyl) amine, trimethoxysilyl undecylamine, trimethoxysilyl-2-chloromethylphenylethane, etc. are mentioned.

Looking specifically at the method for producing a layered organic clay compound according to the present invention, first, the above-described layered clay is dispersed in water or a co-solvent of water and alcohol to make a suspension. The phosphonium cation salt containing the said reactive group is added here, and it fully stirs for 1 to 48 hours at 25-100 degreeC. The mixed solution is centrifuged to obtain a solid, which is washed several times with water to remove residual anions, and then freeze-dried to obtain a layered organic clay substituted with a phosphonium cation salt containing a reactive group.

The organic phosphonium cation salt is preferably included in a molar equivalent of 0.1 to 5 times the cation exchange capacity of the layered clay. At this time, if the content of the phosphonium cation salt is less than 0.1 molar equivalent, the substituted phosphonium cation is too small to improve the physical properties, and if the content exceeds the molar equivalent of 5 times, the excess phosphonium cation is the polyester nanocomposite. It may cause a problem of reducing the physical properties by acting as an impurity in the.

In addition, a layered organic clay substituted with a phosphonium cationic salt containing a reactive group obtained by the above-described method is further dispersed in water or a cosolvent of water and alcohol to prepare a suspension. The silane compound is added thereto and sufficiently stirred at 25 to 200 ° C. for 1 to 48 hours. The mixture is centrifuged to obtain a solid, which is then washed several times with water and freeze-dried to obtain a layered organic clay in which a silane compound is bonded to a phosphonium cation salt.

The silane compound is preferably included in a molar equivalent of 0.1 to 5 times the cation exchange capacity of the layered clay. At this time, if the content of the silane compound is less than 0.1 molar equivalent, the introduced silane compound may be too small to improve the physical properties, and if the content exceeds the molar equivalent of 5 times, the polyester monomer may be due to the reaction between the silane compounds. The reaction with becomes difficult.

In addition, the layered clay substituted with the layered clay and the organic agent is dispersed in water or a co-solvent of water and alcohol. The amount of dispersion of the layered clay substituted with the layered clay or the organic agent included in the water or the co-solvent of water and alcohol is It is preferable to disperse | distribute to 3-30 weight part with respect to 100 weight part of solvents.

The layered organic clay compound according to the present invention thus prepared is excellent in thermal stability, and has a high affinity with the polyester resin.

In addition, in the present invention, after mixing the polyester monomer or oligomer and the layered organic clay compound prepared above, to prepare a polyester nanocomposite through a polymerization reaction.

As the polyester resin usable in the present invention, at least one selected from the group consisting of polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate and copolymers thereof, preferably polyethylene terephthalate to be.

0.1-20 weight part of said layered organic clay compound is used with respect to 100 weight part of polyester monomers, Preferably 0.5-10 weight part is used. If the content of the layered organic clay compound is less than 0.1 part by weight, the amount of the layered organic clay is small, so that the physical properties are difficult to increase.

The polymerization process of the polyester nanocomposite in the present invention is as follows.

(1) Ethylene glycol and terephthalic acid are mixed to a slurry reaction tank at a constant molar ratio, usually in a molar ratio of 1: 1 to 1.5, followed by stirring at room temperature.

(2) The mixture is slowly added to a DE (direct esterification) reactor maintained at a temperature in the range of 240 to 270 ° C. over about 2 to 4 hours to effect esterification to prepare an oligomer. At this time, the same amount of oligomer as the mixture added to promote the esterification reaction in the DE reactor can be added in advance.

(3) After transferring the prepared oligomer to a PC (polycondensation) reactor maintained at a temperature range of 270 ~ 290 ℃, the layered organic clay compound is added and stirred. The layered organic clay compound is prepared by adding layered organic clay and antimony trioxide to ethylene glycol, and then improving dispersibility by using ultrasonic waves when stirring. For the polymerization reaction, the pressure was reduced to 0.3 to 0.5 Torr or less, and the polymerization reaction was performed for about 3 to 4 hours.

(4) When the desired intrinsic viscosity is reached, the reaction is stopped and then discharged to prepare a nanocomposite in chip state.

In the present invention, if necessary, an antioxidant, a heat stabilizer, a colorant, an antistatic agent, an ultraviolet absorber, a flame retardant, etc. may be added to the polyester nanocomposite.

Although the present invention will be described in more detail with reference to the following examples and comparative examples, these examples are for illustrative purposes only and do not limit the scope of the present invention.

Example 1

10 g of montmorillonite was dispersed in 500 ml of water to prepare a suspension, and thereto, phosphonium cationic salt HOC ₁₁ H ₂₂ (C ₆ H ₅ ) ₃ P ⁺ Cl ^- 10 g was added thereto, and the mixture was sufficiently stirred at 70 ° C. for 24 hours. The mixture was centrifuged to obtain a solid, washed with water, and then centrifuged again for three times. The obtained solid was lyophilized to prepare a layered organic clay in powder form.

10 g of the layered organic clay prepared above was dispersed in 500 ml of water to prepare a suspension, and ₂ g of a silane compound, NH ₂ (CH ₂ ) ₂ NH (CH ₂ ) ₃ Si (OCH ₃ ) _3, was added thereto for 24 hours at 70 ° C. Was stirred sufficiently. The mixture was centrifuged to obtain a solid, washed with water, and then centrifuged again for three times. The obtained solid was lyophilized to prepare a layered organic clay in powder form.

8.6 kg of terephthalic acid and 3.8 kg of ethylene glycol were mixed and stirred at room temperature in the slurry reactor. The mixture was slowly added to the DE reactor maintained at 258 ° C. over about 3 hours to carry out an esterification reaction to prepare an oligomer. At this time, the same amount of oligomer as the mixture introduced to promote the esterification reaction was previously added into the DE reactor. Half of the prepared oligomer was transferred to a PC reactor maintained at 285 ° C., and then a layered organic clay mixture was added and stirred. In the layered organic clay mixture, 100 g of the layered organic clay prepared above and 2.8 g of antimony trioxide were added to 1,000 g of ethylene glycol, and then the ultrasonic wave was used to improve dispersibility. For the polymerization reaction, the pressure was reduced to 0.5 Torr or lower and the polymerization reaction was performed for about 3 hours. The reaction was stopped when the intrinsic viscosity reached 0.63 dL / g, and then discharged to prepare a nanocomposite in a chip state according to the present invention. Evaluation of physical properties of the prepared polyester nanocomposite is shown in Table 1 below.

Example 2

10 g of montmorillonite was dispersed in 500 ml of water to prepare a suspension, and thereto, phosphonium cationic salt HOC ₁₁ H ₂₂ (C ₆ H ₅ ) ₃ P ⁺ Cl ^- 10 g was added thereto, and the mixture was sufficiently stirred at 70 ° C. for 24 hours. The mixture was centrifuged to obtain a solid, washed with water, and then centrifuged again for three times. The obtained solid was lyophilized to prepare a layered organic clay in powder form.

10 g of the layered organic clay prepared above was dispersed in 500 ml of water to make a suspension, and ₂ g of the silane compound NH ₂ (CH ₂ ) ₂ NH (CH ₂ ) ₃ Si (OCH ₃ ) ₃ was added thereto at 70 ° C. for 24 hours. Stir enough. The mixture was centrifuged to obtain a solid, washed with water, and then centrifuged again for three times. The obtained solid was dried at room temperature to prepare a layered organic clay in the form of a slurry.

A polyester nanocomposite according to the present invention was prepared in the same manner as in Example 1, except that the layered organic clay in the form of a slurry was used. Evaluation of physical properties of the prepared polyester nanocomposite is shown in Table 1 below.

Comparative Example 1

8.6 kg of terephthalic acid and 3.8 kg of ethylene glycol were mixed and stirred at room temperature in the slurry reactor. The mixture was slowly added to the DE reactor maintained at 258 ° C. over about 3 hours to carry out an esterification reaction to prepare an oligomer. At this time, the same amount of oligomer as the mixture introduced to promote the esterification reaction was previously added into the DE reactor. Half of the prepared oligomer was transferred to a PC reactor maintained at 285 ° C., and then a conventional layered clay mixture was added and stirred. The layered clay mixture was added to 1,000 g of ethylene glycol and 100 g of unorganized montmorillonite and 2.8 g of antimony trioxide were added, and then ultrasonic dispersion was used to improve dispersibility. For the polymerization reaction, the pressure was reduced to 0.5 Torr or lower and the polymerization reaction was performed for about 3 hours. The reaction was stopped when the intrinsic viscosity reached 0.63 dL / g, and then discharged to prepare a polyester nanocomposite in a chip state. Evaluation of physical properties of the prepared polyester nanocomposite is shown in Table 1 below.

Comparative Example 2

Except for applying C ₁₂ H ₂₅ (C ₆ H ₅ ) ₃ P ⁺ Cl ^- in place of HOC ₁₁ H ₂₂ (C ₆ H ₅ ) ₃ P ⁺ Cl ^- as the organic agent in Example 1, Polyester nanocomposites were prepared in the same manner as in Example 1. Evaluation of physical properties of the prepared polyester nanocomposite is shown in Table 1 below.

Comparative Example 3

10 g of montmorillonite was dispersed in 500 ml of water to prepare a suspension, and thereto, phosphonium cationic salt HOC ₁₁ H ₂₂ (C ₆ H ₅ ) ₃ P ⁺ Cl ^- 10 g was added thereto, and the mixture was sufficiently stirred at 70 ° C. for 24 hours. The mixture was centrifuged to obtain a solid, washed with water, and then centrifuged again for three times. The obtained solid was lyophilized to prepare a layered organic clay in powder form.

8.6 kg of terephthalic acid and 3.8 kg of ethylene glycol were mixed and stirred at room temperature in the slurry reactor. The mixture was slowly added to the DE reactor maintained at 258 ° C. over about 3 hours to carry out an esterification reaction to prepare an oligomer. At this time, the same amount of oligomer as the mixture introduced to promote the esterification reaction was previously added into the DE reactor. Half of the prepared oligomer was transferred to a PC reactor maintained at 285 ° C., and then a layered organic clay mixture was added and stirred. In the layered organic clay mixture, 100 g of the layered organic clay and 2.8 g of antimony trioxide were added to 1,000 g of ethylene glycol, and then the ultrasonic wave was used to improve dispersibility. For the polymerization reaction, the pressure was reduced to 0.5 Torr or lower and the polymerization reaction was performed for about 3 hours. The reaction was stopped when the intrinsic viscosity reached 0.63 dL / g, and then discharged to prepare a polyester nanocomposite in a chip state. Evaluation of physical properties of the prepared polyester nanocomposite is shown in Table 1 below.

Example 1 Example 2 Comparative Example 1 Comparative Example 2 Comparative Example 3 Melting Point (℃) 255 255 255 254 255 Crystallization temperature (℃) 205 206 206 204 205 Interlayer distance 23 25 12 19 18 Particle Size (μm) 0.5 0.3 1.5 1.2 1.1 Dispersibility (× 10 ³ / mm ² ) 256 342 67 75 76 Flexural Strength (MPa) 128 136 90 95 98 Flexural Modulus (MPa) 3,670 3,850 2,800 2,950 2,940 Oxygen permeability (cc / m ² · day) 76 62 113 102 103

※ The evaluation method of the physical property used in the Example and the comparative example is as follows.

[Property evaluation method]

1) Melting point and crystallization temperature: measured by differential scanning thermal analyzer (DSC).

2) X-ray diffraction experiment: It was used to measure the interlayer distance of the layered organic clay layer of the polyester nanocomposite.

3) Scanning electron microscope: It was used to investigate the size and dispersibility of the layered organic clay particles of the polyester nanocomposite.

4) Transmission electron microscope: It was used to observe the morphology of the layered organic clay layers of the polyester nanocomposite.

5) Flexural strength and flexural modulus: The width of the specimen was 13 mm, the thickness was 3.4 mm, and the span length was 54 mm according to ASTM D790, and then measured at a speed of 2 mm / min. At this time, the measurement temperature was 23 degreeC and the relative humidity was maintained at 55%.

6) Oxygen Permeability: After the biaxially stretched film was placed on an oxygen permeability measuring device (Mocon Ox-Tran 2/20), the measurement was performed at a temperature of 23 ° C. for 24 hours. The relative humidity of oxygen and carrier gas (98% nitrogen + 2% hydrogen) was maintained at 55%.

As can be seen through Table 1, the polyester nanocomposites of Examples 1 and 2 according to the present invention has a larger interlayer distance of the layered organic clay compared to the nanocomposites of Comparative Examples 1 to 3 and facilitates the insertion of polymers. In addition, the dispersibility was improved, and it was confirmed that it had excellent flexural modulus and low oxygen permeability.

The layered organic clay compound according to the present invention has excellent thermal stability, high affinity with a polyester monomer, and the polyester nanocomposite according to the present invention has excellent thermal stability, mechanical strength and gas barrier property, so that films, containers, engineering It can be used in the manufacture of plastics, tire cord reinforcements and the like.

Claims (8)

Adding a layered clay and an organizing agent containing a reactive group in a molar equivalent of 0.1 to 5 times the cation exchange capacity of the layered clay to provide a layered clay substituted with the organizing agent; And Adding and stirring the silane compound in a molar equivalent of 0.1 to 5 times the cation exchange capacity of the layered clay; Method for producing a layered organic clay compound comprising a. The method for preparing a layered organic clay compound according to claim 1, wherein the layered clay has a cation exchange capacity of 20 meq / 100 g to 200 meq / 100 g. The method of claim 1, wherein the organic agent comprising a reactive group is a phosphonium cation salt represented by the following formula (1). Formula 1 Wherein R ₁ , R ₂ , R ₃ and R ₄ are the same as or different from each other, and are aliphatic hydrocarbons having 4 to 40 carbon atoms, and at least one of R ₁ to R ₄ is a carboxyl group, an amine group, a hydroxy group, an ester group, It is a reactive group chosen from the group which consists of an epoxy group, a silanol group, a carbonate group, and an imide group. The method of claim 1, wherein the silane compound is vinylchlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, octadecyltrimethoxysilane, gammaaminopropyltrimethoxysilane, gammaaminopropyltriethoxysilane, N -(2-aminoethyl) -3-aminopropyltrimethoxysilane, N- (2-vinylbenzylaminoethyl) -3-aminopropyltrimethoxysilane, N-phenyl-gammaaminopropyltrimethoxysilane, gamma Glycidoxypropyltrimethoxysilane, gamma methacryloxypropyltrimethoxysilane, gamma mercaptopropyltrimethoxysilane, gamma-aminopropylphenyldimethoxysilane, gamma propionamido trimethoxysilane, N-trimeth Layered organic clay compound, characterized in that at least one selected from the group consisting of oxysilylpropyl-N (beta-aminoethyl) amine, trimethoxysilylundecylamine and trimethoxysilyl-2-chloromethylphenylethane Manufacturing method. The method of claim 1, wherein the layered clay is at least one selected from the group consisting of montmorillonite, bentonite, hectorite, hectoride fluoride, Weidelite, saponite, nontronite, vermiculite, macadamite, mica, and fluorinated mica Method for producing a layered organic clay compound, characterized in that. A layered organic clay compound prepared by the process according to any one of claims 1 to 5. A polyester nanocomposite, which is prepared by polymerizing a polyester monomer by adding 0.1 to 20 parts by weight of the layered organic clay compound according to claim 6 to 100 parts by weight of a polyester monomer. The polyester according to claim 7, wherein the polyester monomer is selected from the group consisting of polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and copolymers thereof. Nanocomposites.