DK151816B - HYDROGEL WITH APPLICABILITY AS MEDICAL HYDROGEL AND METHOD OF PRODUCING THEREOF - Google Patents

Description

DK 151816 B

The present invention relates to a hydrogel useful as a medical hydrogel (such as contact lenses, artificial organs, etc.) and consisting of a chemically bonded, phase-separated, self-cured, thermoplastic, water-insoluble, water-swellable graft copolymer and from ca. 10% by weight to approx. 95% by weight of water, based on the weight of the copolymer, which copolymer is prepared by copolymerization of a hydrophobic macromolecular monomer and a hydrophilic copolymerizable monomer.

Considerable research and development has been devoted to the purpose of obtaining hydrophilic polymers having sufficient wet strength to be rendered substantially water insoluble. Eg. is a type of increased wet strength hydrophilic polymer described in U.S.A. U.S. Patent Nos. 2,976,576 and 3,220,960 (Otto Wichterle et al. and

2; DK 151816 B

M.E. Ref030 et al., Journal of Applied Polymer Science, Vol. 9, pages 2425-2435 (1965)). Pissing polymers are prepared by simultaneously polymerizing a water-soluble monoester of acrylic acid or methacrylic acid in which the ester moiety contains at least one hydrophilic group, such as a hydroxy group, and cross-linking the monomer with a polyunsaturated, crosslinking agent such as ethylene glycol dimethacrylate as it polymerizes. The amount of such a cross-linking agent is usually less than about 10%. 1 molfo of the monoester. Such polymerizations are generally carried out in the presence of a redox initiator.

10 Hydrophilic polymers with improved wet strength derived from a polymer obtained by copolymerizing a water-soluble vinyl monomer containing at least one nitrogen atom with a small amount of a bifunctional monomer have also been described. Pissing polymers have been proposed as being useful for various biomedical applications due to their compatibility with body tissues and / or mucosa. Some of these polymers are described in U.S.A. U.S. Patent Nos. 3,659,524 and 5,767,731 (Maurice Seiderman).

One of the necessary factors in the preparation of these known hydrophilic polymers having an increased wet strength consists in the use of a small amount of polyunsaturated, crosslinking agent. Since the amount of crosslinking agent used is generally very small, the amount can be varied only slightly. Therefore, it is not possible to effectively adjust the final properties of the hydrophilic polymer by varying the amount of crosslinking agent. Various attempts to avoid this problem have been described in U.S.A. U.S. Patent No. 3,503,942 (Seiderman) and U.S. Pat. Patent No. 3,758,448 (Paul Stamberger).

IN USA. U.S. Patent No. 3,786,116 describes the pioneering discovery in the preparation of chemically linked, phase-separated, thermoplastic graft copolymers. These copolymers are basically polymers of the physically cross-linked type (as opposed to chemically cross-linked) and have been referred to as "self-cured" or "self-reinforced" thermoplastic graft copolymers. This phenomenon arises by providing a controlled dispersion of a single phase macromolecular side chain within the polymer phase backbone (matrix). Because all the macromolecular monomer side chain regions are an integral part or are placed between large ·. ν 'DK 151816Β 3 segments of the polymer backbone, has the resulting graft copolymer properties as a cross-linked polymer if there is a large difference between Tg or Tm in the backbone and the side chain segments.

This is the case up to the temperature required for breaking 5 of the thermodynamic crosslink in the dispersed phase. In order for the dispersed phase region of the graft copolymers to impart the desired crosslinking or "self-curing" effect, it is important that the macromolecular monomers comprising the dispersed phase region have substantially the same molecular weight, i.e. that the 10 macromolecular monomers must have a Mw / Mn ratio which is not substantially above ca. 1.1. Macromolecular monomers having a wider molecular weight distribution, i.e. a ratio of approx. 1.5 or 2, will usually comprise very low molecular weight polymers which impart a "copolymeric" effect on the polymer backbone, and very high molecular weight polymers which will form another dispersed phase or region having a size. , which is different from the mainly dispersed phase. The end result is a poor quality opaque polymer in relation to the desired physical properties of the polymer backbone.

The hydrogel according to the invention is characterized by the characterizing part of claim 1.

Compared to the known outer hydrogels, the hydrogel according to the invention is transparent and clear and can therefore be used as a medical hydrogel such as contact lenses, artificial organs, etc. The copolymer contained in the hydrogel can produce moisture absorption and water permeability (useful for dialysis tubes) as well as impart antistatic properties to various products.

The graft copolymer of the hydrogel of the invention assumes a "T" type structure when only one side chain is copolymerized into the hydrophilic, co-3q polymeric backbone. However, when more than one side chain is copolymerized into the hydrophilic polymer backbone, the graft copolymer can be characterized as having a comb-like shape, illustrated as follows:

DK 151816B

4 c-c-c-b-c-c-c-b-c-c-c ...

I I

a a

I I

a a

I I

aa wherein "a" represents a substantially linear, normally hydrophobic polymer of uniform molecular weight or a copolymer of sufficient molecular weight to express the physical properties of at least one of the substantially linear, hydrophobic polymers, and "b "5" represents a reacted and copolymerized end group chemically bonded to the side chain "a" integrally copolymerized into the polymer backbone, and "c" is the hydrophilic polymer backbone with uninterrupted molecular weight segments to provide the physical properties of The hydrophilic polymer is expressed. The basic skeleton of the graft copolymer of the hydrogel according to the invention contains at least approx. 20 uninterrupted returned monomeric units in each segment. However, it has been found that at least approx. 100 uninterrupted recurrent monomeric units in each segment provide particularly desirable physical properties. It has been found that this state provides a graft copolymer having the same properties as the hydrophilic polymer backbone. In other words, the presence of segments containing at least approx. 20 uninterrupted recurrent monomeric units graft copolymers with the physical properties associated with the polymeric backbone, such as water solubility and water swelling properties.

The polymeric backbone segments of the chemically bonded, phase-separated, self-cured, hydrophilic, thermoplastic graft copolymer in the hydrogel of the invention are derived from acrylic acid, a hydroxyalkyl acrylate, a dialkylacrylamide or vinyl acetate.

The invention further relates to a process for the preparation of the present hydrogel, which is characterized by the method of claim 7.

A particularly preferred example of hydrophilic monomer is vinyl acetate.

5

DK 151816 B

The vinyl acetate is copolymerized with the copolymerizable, hydrophobic, macromolecular monomer having a copolymerizable double bond at its molecular chain end, and after copolymerization, the resulting graft copolymer is saponified to make the polymeric backbone hydrophilic. In other words, the polymeric backbone contains polyvinyl alcohol.

As will be apparent from the description of the copolymerizable macromolecular monomers described below, the choice of the copolymerizable end groups includes any commercially available copolymerizable monomer. Accordingly, the choice of respective copolymerizable end groups on the macromolecular monomer as well as the copolymerizable monomer can be made based on relative reactivity conditions under the respective copolymerization reaction conditions suitable for copolymerization. Thus, by simply examining the reactivity of various comonomer pairs in the literature, one is able to provide the appropriate end group on the macromolecular monomer and the copolymerizable monomer. Preferably, the r-values of the respective copolymerizable moieties will be as close to unity as possible, as will be well known to those skilled in the art of copolymerization. Eg. copolymerizes an acrylate or methacrylate-terminated macromolecular monomer with acrylates and methacrylates under free radical conditions in a manner determined by the respective reactivity conditions of the monomers.

As will be explained below, the preferred combination of favorable properties that the graft copolymer of the hydrogel of the invention possesses, the large segments of uninterrupted copolymers, hydrophilic skeletons, and the integrally copolymerized, linear, hydrophobic polymers controlled molecular weight side chains and narrow molecular weight distribution.

The term "linear" as discussed above is used in the usual sense of the term to refer to a polymeric backbone which is free of crosslinking.

The term "hydrophilic" as mentioned above is used in its conventional sense to refer to a polymeric or monomeric substance or system which absorbs or adsorbs water.

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DK 151816 B

The term "hydrophobic" as discussed above is used in its conventional sense to refer to a polymeric substance which rejects water.

The side chain polymers having substantially uniform molecular weight 5 comprise substantially linear, hydrophobic polymers and copolymers prepared by anionic polymerization of an anionic; polymerizable monomer, as mentioned above, or mixture thereof, resulting in a polymer which is hydrophobic. The side chain polymer will apparently be different from the hydrophilic polymer backbone.

It is preferred that at least one segment of the graft copolymer side chain polymer of the present invention has a molecular weight sufficient to express favorable properties of the respective polymers. In other words, the physical properties of the side chain polymers, such as the glass transition temperature (Tg), will be expressed. The molecular weight of the polymeric side chains is between 2,000 and 50,000. Particularly desirable results have been obtained when the polymeric side chains have a molecular weight in the range of approx. 10,000 to approx. 35,000, preferably in the range of from approx. 12,000 to approx. 25,000.

In view of the unusual and improved physical properties possessed by the thermoplastic graft copolymer in the hydrogel of the invention, it is believed that the monofunctionally bound polymeric side chains which have a substantially uniform molecular weight form what are known as "regions" , which appear as scattered droplets deposited in the matrix matrix of the polymer backbone. Since the regions or droplets are microscopic, they are generally below wavelength too light through the base skeletal polymer. The final obtained podeco polymer is clear or transparent. The hydrophobic polymeric side chains which produce the self-curing or self-reinforcing effect on the hydrophilic polymer backbone increase the wet strength of the final polymer.

The copolymerizable, hydrophobic, macromolecular monomers.

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DK 151816 B

The hydrophobic polymeric side chains of the chemically bonded, phase-separated, self-cured, hydrophilic graft copolymers are preferably produced by anionic polymerization of a polymerizable monomer or combination of monomers. Such monomers have the formula r [z] · X, where 5 r is a lower alkyl group, Z is repeating monomer units of a vinyl aromatic compound: with up to 12 carbon atoms and / or of a conjugated diene of 4-8 carbon atoms, with a value such that the molecular weight of the polymer is between 2,000 and 50,000, and X is a polymerizable group. The first step in preparing the copolymerizable, hydrophobic, macromolecular monomers consists in producing reactive polymers. Reactive polymers are conveniently prepared by contacting the monomer with an alkali metal hydrocarbon or alkoxide salts in the presence of an inert organic diluent which does not participate in or generate the polymerization reaction.

The monomers containing olefinic groups suitable for preparing the hydrophobic macromolecular monomers are, as mentioned, the conjugated dienes containing 4 to 8 carbon atoms per minute. molecule, 2o, and the vinyl-substituted aromatic hydrocarbons containing up to ca. 12 carbon atoms. Particularly preferred monomers include styrene, α-methylstyrene, butadiene and isoprene.

The initiators of these anionic polymerizations are any alkali metal hydrocarbons and alkoxide salts which form a monofunctional reactive polymer, i.e. only one end of the polymer contains a reactive anion. The catalysts found suitable include hydrocarbons having lithium, sodium or potassium represented by the formula RMe, wherein Me represents an alkali metal such as sodium, lithium or potassium, and R represents a hydrocarbon group, e.g. an alkyl group containing up to approx. 20 or more carbon atoms, preferably up to about 8 carbon atoms, an aryl group, an alkyl group or an aralkyl group. Examples of alkali metal hydrocarbons include ethyl sodium, n-propyl sodium, n-butyl potassium,

DK 151816 B

8 n-octyl potassium, phenyl sodium, ethylthithium, sec-butyllithium, t-butyllithium and 2-ethylhexyllithium. Sec-butyllithium is the preferred retarding initiator because it has a rapid initiation which is important in the preparation of polymers with narrow molecular weight distribution. It is preferred to use the alkali metal salts of tertiary alcohols such as potassium t-butyl alkoxylate when polymerizing monomers with a nitrile or carbonyl functional group.

in

The alkali metal hydrocarbons and alkali metal alkoxylates are either commercially available compounds or can be prepared by known methods, such as by reacting a halogenated hydrocarbon, a halogenobenzene or an alcohol with the appropriate alkali metal.

in

Generally, an inert solvent is used to facilitate heat transfer and appropriate mixing of initiator and monomer.

Hydrocarbons and ethers are the preferred solvents. Solvents useful in the anionic polymerization processes include the aromatic hydrocarbons such as benzene, toluene, xylene, ethylbenzene, t-butylbenzene, etc. Suitable are also the saturated aliphatic and cycloaliphatic hydrocarbons such as n-hexane. n-heptane, n-octane, cyclohexane and the like. In addition, aliphatic and cyclic ether solvents, e.g. dimethyl ether, diethyl ether, dibutyl ether, tetrahydrofuran, dioxane, anisole, tetrahydropyran, diglyme, glyme, etc .. The rates of polymerization are higher in the ether solvents than in the hydrocarbon solvents and small amounts of ether in the hydrocarbon solvent increase polymerization.

The initiator amount is an important factor in anionic polymerization because it determines the molecular weight of the reactive polymer.

DK 151816 B

r 9

If a small amount of initiator is used relative to the amount of monomer, the molecular weight of the reactive polymer will be greater than 5 if a greater amount of initiator is used. In general, it is advisable to add the initiator dropwise to the monomer (when it is the order of addition) until the characteristic color of the organic anion persists, and then add the calculated amount of initiator to the desired molecular weight. The preliminary drop addition serves to destroy contaminants and thus enables better control of the polymerization.

For the preparation of a polymer with narrow molecular weight distribution, it is generally preferred to simultaneously introduce all the relative types of substances into the system. By this technique, polymer growth is accomplished by the subsequent addition of monomers at the same rate to an active, terminated group, without chain transfer or termination. Once this is done, the molecular weight of the polymer is controlled by the ratio of monomer to initiator, as can be seen from the following equation: molecular weight - moi monomer molecular weight τα .., a ,. -i mole initiator x a reactive polymer monomer 20 As can be seen from the above equation, high initiator concentrations lead to the formation of low molecular weight polymers, whereas low initiator concentrations lead to the formation of high molecular weight polymers.

The concentration of the monomer loaded on the reaction vessel may vary within wide limits and is limited by the ability of the reaction apparatus to remove the heat of polymerization and to appropriately mix the resulting viscous solutions of the reactive polymer. Monomer concentrations as high as 50% by weight or more based on the weight of the reaction mixture can be used. However, the preferred monomer concentration ranges from ca. 5 ° to approx. 251 ° to obtain a suitable mixture.

DK 151816 B

As can be seen from the above formula and the aforementioned "monomer concentration limitations, the initiator concentration is critical, but can be varied according to the desired molecular weight of the reactive polymer and the relative concentration of the monomer. In general, the initiator concentration may be from about 0.001 to about 0.1 mole of active alkali metal per mole of monomer or more The initiator concentration will preferably range from about 0.01 to about 0.004 mole of active alkali metal per mole of monomer.

The polymerization temperature will depend on the monomer. In general, the reaction can be carried out at temperatures of about -100 ° 0 and up to approx.

100 ° G. When aliphatic hydrocarbon diluents are used, the preferred temperature is from approx. -10 ° 0 to approx. 100 ° C. With ethers as the solvent, the preferred temperature ranges from approx. -100 ° C to approx. 100 ° 0th The polymerization of styrene is generally carried out at slightly above room temperature, and polymerization of α-methylstyrene is preferably carried out at lower temperatures, e.g. -80.

The preparation of the reactive polymer can be carried out by adding a solution of the alkali metal hydrocarbon initiator in an inert organic solvent to a mixture of monomer and diluent at the desired polymerization temperature, and leaving the mixture with or without stirring until the polymerization is complete. . An alternative method consists of adding monomer to a solution of the catalyst in the diluent at the desired polymerization temperature and at the rate at which it is polymerized. In both processes, the monomer is quantitatively converted to a reactive polymer as long as the system remains free of impurities which inactivate the anionic types of substance. However, as stated above, it is important to add all of the reactive components together and quickly to ensure uniform molecular weight distribution of the polymer.

The anionic polymerization must be carried out under carefully controlled conditions to exclude substances that destroy the catalytic action of the catalyst or initiator. Eg. such impurities as water, oxygen, carbon monoxide, carbon dioxide and the like.

Thus, the polymerizations are generally carried out in dry equipment using anhydrous reactants and under an inert gas atmosphere such as nitrogen, helium, argon, methane and the like.

Γ

u DK 151816 B

The reactive polymers described above are capable of undergoing further reactions including further polymerization.

Thus, if an additional monomer such as styrene is added to the reactive polymer, the polymerization is renewed and the chain grows until no more monomeric styrene is left. Alternatively, if another different anionic polymerizable monomer is added, such as butadiene or ethylene oxide, the above reactive polymer initiates the polymerization of the butadiene or ethylene oxide, and the finally obtained reactive polymer resulting therefrom is made of a polystyrene segment and a polybutadiene or polyoxyethylene. -segment.

A diblock-hydrophobic copolymer can be prepared by bringing the first reactive polymer, e.g. a reactive polymer of a vinyl-aromatic compound such as reactive polystyrene or reactive poly (α-methylstyrene) in contact with another anionic polymerizable monomer, e.g. a conjugated diene such as butadiene or isoprene. In this way, a reactive diblock polymer is obtained which can be terminated by the methods used in the practice of the present invention. Using this technique, a reactive diblock polymer of the following formula can be obtained: Θ

A-B

wherein A is a polymer block of a vinyl-aromatic compound and B is a polymer block of a conjugated diene. Copolymerizable, macro-molecular monomers having a diblock structure are described in U.S.A.

25 Patent Application Serial Ho. 347.116. '

As stated above, the reactive polymers used in the process of the present invention are characterized by a relatively uniform molecular weight, i.e. that the distribution of molecular weights in the mixture of prepared reactive polymers is quite narrow. This is in marked contrast to the typical polymer, where the molecular weight distribution is quite wide. The difference in molecular weight distribution is particularly evident from an analysis of the gel permeation chromatogram of commercial polystyrene (Dow 666u) produced by free radical polymerization and of polystyrene prepared by the anionic polymerization process used in the practice of the process of the invention. They are responsive

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Thus, polymers prepared by the process of the invention are characterized by having an Mw / Mn ratio which is not substantially greater than ca. 1.1, where Mw is the weighted average molecular weight of the reactive polymer and Mn is the number of numerical average molecular weight of the reactive polymer determined by conventional analytical techniques such as gel permeation chromatography (G-PC).

The reactive polymers herein are terminated by reaction with a halogen-containing compound which also contains a polymerizable moiety such as an olefinic group or an epoxy or thioepoxy group. Suitable halogen-containing termination agents include the vinyl haloalkyl ethers wherein the alkyl groups contain 6 or fewer carbon atoms, such as methyl, ethyl, propyl, butyl, isobutyl, sec-butyl, amyl and hexyl, vinyl esters or haloalkanoic acids, wherein the alkanoic acid contains 6 or fewer carbon atoms. , such as acetic acid, propionic acid, butyric acid, valeric acid and capric acid, olefinic halides with 6 or fewer carbon atoms such as vinyl halide, allyl halide, methallyl halide, 6-halo-1-hexene, etc., halides of dienes such as 2-halo methyl-1 ; or propylene oxide. The halogen group may be chlorine, fluorine, bromine or iodine, but preferably it is chlorine. Anhydrides of compounds with an olefinic group or an epoxy or thioepoxy group may also be used, such as maleic anhydride, acrylic anhydride or methacrylic anhydride.

Termination of the reactive polymer is accomplished simply by adding the termination agent to the solution of reactive polymer at the temperature at which the reactive polymer is prepared. The turnover is immediate and the yield is theoretical. A slight molar excess of the terminating agent relative to the amount of anionic initiator may be employed, although the reaction is carried out on a mole-to-mole basis.

The termination may be carried out in any suitable inert

is DK 151816 B

is solvent. In general, it is advisable to use the same solvent system as used in the preparation of the reactive polymer. . ·. A preferred embodiment of the process of the invention comprises performing the termination reaction in a hydrocarbon solvent instead of the polar ether-type solvents such as tetrahydrofuran. It has been found that hydrocarbon solvents such as the aromatic hydrocarbons, saturated aliphatic and cycloaliphatic hydrocarbons cause several differences in the reaction conditions and in the resulting product. F.

For example, the quenching reaction can be carried out at higher temperatures with hydrocarbon solvents than with the ether solvents.

Due to the nature of the reactive polymer and the monomer from which it is made, or because of the nature of the terminating agent, in some cases, certain adverse side reactions occur, resulting in an impure product. P.eks. For example, the carbanion in certain reactive polymers tends to react with functional groups or any active hydrogen atoms in the terminating agent. Thus, although acrylyl chloride or methacrylyl chloride act as termination agents due to the presence of the ehlor atom 20 in their structure, they thus provide e.g. also a carbonyl group in the terminated polymer chain, and this carbonyl group can provide a center of attack by another highly reactive polymer. The resulting polymer either has twice the expected molecular weight or contains some chlorine, which shows that some of the reactive polymer has been terminated by reaction with another reactive polymer or with one of the active hydrocarbons from the acrylyl or methacrylyl chloride. .

It has been found that the means for alleviating the above drawback are to make the reactive carbanion less susceptible to reaction with the functional groups or any active hydrogen atoms of a termination agent. A preferred method of making the reactive polymer more susceptible to the adverse reaction consists of "protecting" the particularly reactive polymer with a less reactive reactant. Examples of some preferred "protecting agents" include the lower alkylene oxides, i.e. one having 8 or fewer carbon atoms, such as ethylene and propylene oxide, diphenyl = ethylene, etc. The "protective" reaction gives a product which still

14 DK 151816B

is a reactive polymer, but provides a cleaner product when then reacted with a termination agent containing a functional group or active hydrogen.

It has been found that diphenylethylene is an excellent "protector" part 5 when terminating agents such as e.g. vinylchloralkanoater.

A particularly preferred "protective agent" is an alkylene oxide such as ethylene oxide. This reacts with the reactive polymer during degradation of its oxirane ring. The following is a typical illustration of the "protective reaction" which shows the reaction of ethylene = 10 oxide as a covering agent with a reactive polymer prepared by polymerization of styrene with sec-butyllithium as initiator: ΓΊΘΘ ΓΊ ΘΘ sec.-Bu- -CHOCH —- CHOCH li + CH0 GH9 -> - sec.-Bu - CHOCH - CHCJCH — CH9CH90H-II 16¾ v 1 6¾

The · protective reaction is carried out quite simply as in the case of the termination reaction by adding the covering reactant to the reactive polymer at polymerization temperatures. Reaction 15 takes place immediately, just as in the case of the termination reaction, a slight molar excess of the covering reactant can be used relative to the amount of initiator. The reaction takes place on a mole-to-mole basis.

It will be seen that when a large molar excess of alkylene oxide is reacted with the reactive polymer, a reactive polymer having two polymeric blocks is prepared. A typical example of polystyrene segments and polyoxyalkylene segments is as follows: “1 Θ ® sec.- Bu — CH2CH — CH2CH (CH2CH2O) x—

Conveniently, both of the above described with ethylene oxide "protected" polymers may be terminated with a compound containing a moiety which can react with the anion of the covered polymer and a polymerizable end group, including the following typical compounds: acrylyl chloride, methacrylyl chloride, vinyl 2-chloroethyl ether. , vinyl chloroacetate, r

DK 151816 B

chloromethylmaleic anhydride and esters thereof, maleic anhydride (yields half esters of maleic acid after protonation with water), allyl chloride and methallyl chloride, and vinyl benzyl chloride.

The reaction of the above "protected" reactive polymers with both acrylyl chloride and methacrylyl chloride can be illustrated by the following reactions:

II

ch2 = c - c - Cl. . © Θ sec.-Bu ^ -CH2-CH - (0Η20Η20) χ — CH2CH20 + li --- ► L bi r -I o

,. II

sec-Bu - CH2-OH - (CH2 CH2 O) x-CH2 OH2OCC = CH2 + LiCl c. O Jn H «wherein n is a positive integer of about number and R 1 is either hydrogen or methyl.

When an epihalohydrin is used as the final reagent, the resulting polymer contains a terminal epoxy group. This terminal epoxy group can itself be used as the polymerizable group, such as in the preparation of a polypropylene oxide backbone graft copolymer, or can be converted to various other useful polymerizable end groups by any of several known reactions.

As an embodiment of the process according to the invention, the finished reactive polymer containing an epoxy or thioepoxy end group can be reacted with a polymerizable carboxylic acid halide, such as acrylic acid halide, methacrylic acid halide or maleic acid halide, to prepare a p-hydroxyalkyl, methacrylate or maleate ester as the polymerizable end portion of the polymer of substantially uniform molecular weight. The same polymerizable esters can be prepared from the epoxy-terminated polymer by first converting the epoxy group to the corresponding glycol by heating the polymer together with aqueous sodium hydroxide, followed by conventional esterification of the glycol end group with the appropriate polymerizable carboxylic acid or acid halide.

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The resulting glycol obtained by the aqueous hydrolysis of the epoxy group in the presence of a rabbit can be converted to a copolymer by reaction with a high molecular weight dicarboxylic acid, such as may be prepared by polymerization of a glycol or diamine with a 5 molar excess. of phthalic anhydride, maleic anhydride, succinic anhydride or the like. These reactions can be modified to obtain a polystyrene cap and a polyamide cap (nylon). The glycol-terminated polymer can also be reacted with a diisocyanate to form a polyurethane. The diisocyanate can e.g. be the reaction product 10 of a polyethylene glycol having an average molecular weight of 400 with a molar excess of phenylene diisocyanate.

In another embodiment of the invention, an organic epoxide is copolymerized with a terminated polymer containing an epoxy or thioepoxy end group. The resultant graft copolymer is characterized by a base skeleton with continuous segments of at least approx. 20 and preferably at least approx. 30 recurring units of the organic epoxide. Preferred organic epoxides include ethylene oxide, cyclohexene = epoxide and styrene oxide, i.e. those with 8 or fewer carbon atoms. With simple hydrolysis, the backbone polymer can be made hydrophilic.

If it is desirable to isolate and further purify the macromolecular monomer of the solvent from which it was prepared, any of the known methods employed by those skilled in the art can be employed in the recovery of polymeric materials. These methods include: (1) solvent-non-solvent precipitation, (2) solvent evaporation in an aqueous medium, and (3) solvent evaporation such as vacuum roll drying, spray drying, freeze drying, and (4) steam jet coagulation.

Isolation and recovery of the macromolecular monomer is not a critical feature of the invention. In fact, the macromolecular monomer need not be recovered at all. As stated otherwise, the macromolecular monomer, once formed, can be combined with the appropriate monomer and polymerization catalyst to perform the graft copolymerization in the same system as that in which the macromolecular monomer was prepared, provided that the solvent 35 and the materials in the macromolecular monomer preparation container do not poison the catalyst or act in a harmful way

17 DK 151816B

to the graft copolymerization process. Thus, careful selection of the solvent and purification of the reactor system in the preparation of the macromolecular monomer can ultimately result in a great saving in the preparation of the graft copolymers of the invention.

As stated above, the macromolecular monomers, which eventually become the side chains of the graft copolymers by being integrally polymerized into basic le tp o lymers, must exhibit a narrow molecular weight distribution. methods for determining the molecular weight distribution for polymers, such as the macromolecular monomers, are known. Using these known methods, the weighted average molecular weight (Mw) and the numerically average molecular weight (Mn) can be determined and the molecular weight distribution (Mw / Mn) can be determined for the macromolecular monomer. The macromolecular monomers 25 must have almost a Poisson molecular weight distribution or, in fact, be monodisperse in order to have the highest degree of functionality, i.e. that the ratio Mw / Mn will not be significantly above 1.1. Preferably, the ratio Mw / Mn of the novel macromolecular monomers will be less than ca. 1.1. The macromolecular monomers of the present invention, as mentioned above, have a narrow molecular weight distribution as well as purity following the process of their preparation, as described above. Thus, it is important that the sequence of steps in preparing the macromolecular monomers be maintained in order to obtain the optimum results in terms of the favorable properties of the graft copolymers.

As can be seen from the foregoing, the hydrophobic copolymerizable macromolecular monomers of the present invention are generally indicated by the following structural formula:

W “O—”

II

O — pcj ✓'Τ '*

O CM

W

U p 3/1

H \ M

ω o j 0 o

'T

0 = 0 w σ1

ISLAND

U

(D

I h

H

(1)

CO

ft

CM

W

ISLAND

w

___ISLAND

i__I

CM

ω

ISLAND

J?

CM

PM

V4 / ^ ri

H

FM

H

Wherein I is the residual residue of the monofunctional anionic initiator, P is at least one anionic polymerized monomer, P is at least one anionic polymerized monomer which is the same or different from P1, E is either hydrogen or lower alkyl, R 'is either hydrogen or

ISLAND

II

-C-ox, wherein X is either hydrogen, lower alkyl or a monovalent metal, n is a positive integer of at least ca. 20, m is either 0 or a positive integer, and the sum of n and m is such that the molecular weight of the macromolecular monomer is at least approx. 2000 and preferably between approx. 5000 and approx. 50,000, o, q, r and s are either 0 or 1, and p is either 0 or a positive integer in the range of 1 to approx. 8, with the proviso that when o and p are 1, q is equal to 0, r is 0 or 1, s is 0 or 1, and t is 0, and when o is 0, p can be a positive, whole number, and q, r, s and t can be 0 or 1, when o, q, r, s and t are 0, p is a positive integer, s can be 0 or 1, and u and v are either 0 or 1, with the proviso that when u is 1, v is equal to 0, and when v is 1, u is equal to 0, which copolymerizable macromolecular monomer is characterized by having a substantially uniform molecular weight distribution, so that its Mw / Mn ratio is not substantially above approx. 1.1, where Mw is the weighted average molecular weight of the monomer and Mn is the numerically average molecular weight of the monomer.

1 2

As mentioned above, P and P are polymers of vinyl aromatic compounds and conjugated dienes.

The copolymerizable hydrophilic (water-soluble) compounds.

The copolymerizable monomers suitable for obtaining the hydrophilic polymeric backbone of the graft copolymer must be water soluble or capable of being made water soluble after copolymer isation. These compounds are selected from acrylic acid, a hydroxyalkyl acrylate, a dialkylacrylamide or vinyl acetate.

The above "copolymerizable, hydrophobic, copolymerizable, macromolecular monomer" copolymerized with the copolymerizable comonomer forming the hydrophilic copolymeric backbone7 20

DK 151816 B

should be present in quantities ranging from approx. 1 weight $ to approx. 95% by weight relative to the copolymerizable comonomer which forms the hydrophilic polymeric backbone. Stated otherwise, the chemically bonded, phase-separated, thermoplastic graft copolymers which have hydrophilic polymeric backbones comprise (1) from ca. 1 weight $ to approx. 95% by weight of the copolymerizable, hydrophobic, macromolecular monomer having a narrow molecular weight distribution, and (2) from ca. $ 99 weight to approx. 5% by weight of the copolymerizable monomer forming the hydrophilic polymeric backbone. Preferably, the graft copolymer will contain up to ca. About 60% by weight and preferably from ca. 2% by weight to approx.

40 weight fo of the hydrophobic macromolecular monomer described above to obtain the final mechanical strength of the polymer.

The copolymerization of the copolymerizable, hydrophobic, macromolecular monomer and the copolymerizable monomer forming the hydrophilic polymeric backbone of the graft copolymer (and optionally a small amount of a suitable monomer or modifying monomer sometimes referred to in the prior art) , can be performed by solution polymerization, emulsion polymerization, bulk polymerization, suspension polymerization and non-aqueous suspension polymerization.

It is generally desirable, upon completion of the copolymerization reaction, to remove any copolymerizable, hydrophobic, macromolecular monomer that has remained unreacted in the polymerization system. The removal of the mafromomolecular monomer can be accomplished by any suitable means, such as solvent extraction.

If desired, and especially in the case of bulk polymerization, the copolymerization may be carried out in a molded form, such as a contact lens mold.

In such a case, a cross-linking agent may be added during the copolymerization reaction to further enhance the wet-jet properties of the graft copolymer. Suitable crosslinking agents for this purpose include ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, divinylbenzene and ΪΤ, Κ-methylene-bis-methacrylamide. The amount of crosslinking agent used generally depends on the degree of crosslinking desired. Appropriate amounts of cross-linking agent may range from approx. 0.1 wt. 2 weight percent or generally less than 1 mole $ based on the weight of the monomer forming the hydrophilic polymeric backbone.

Γ DK 151816 Β 21

If a polymerization catalyst is used for the copolymerization, polymerization conditions appropriate for the catalyst should be used. P.eks. For example, oil or solvent-soluble peroxides such as benzoyl peroxide are generally effective when the copolymerizable, hydrophobic, macromolecular monomer is copolymerized with an ethylenically unsaturated monomer under bulk conditions, in solution in an organic solvent such as benzene, cyclohexane, toluene and xylene, etc. or in aqueous suspension. Water-soluble peroxides, such as sodium, potassium, lithium and ammonium persulfates, etc., are useful in aqueous suspension and in emulsion systems. In the copolymerization of many of the copolymerizable, hydrophobic, macromolecular monomers, such as those having an ethylenically unsaturated end group and a polystyrene, polyisoprene or polybutadiene repeat unit, an emulsifier or dispersant can be used in an aqueous suspension system. In these systems, particular advantages can be obtained by dissolving the water-insoluble polymerizable macromolecular monomer in a small amount of a suitable solvent, such as a hydrocarbon. By this novel technique, the comonomer copolymerizes with the polymerizable macromolecular monomer 20. in the solvent, in an aqueous system surrounding the solvent polymer is stained. The polymerization catalyst is of course selected so that it will be soluble in the organic phase of the polymerization system.

The polymerization catalyst used may be any of the catalysts suitable for polymerizing compounds containing ethylenic unsaturation (provided that the above criteria are met) and which are preferably free-radical catalysts. Of particular interest are catalysts such as azobisisobutyronitrile and peroxide catalysts. Some examples of suitable peroxide = catalysts include hydrogen peroxide, benzoyl peroxide, tert-butyl peroctoate, phthalic acid peroxide, succinic peroxide, benzoylacetic acid peroxide, coconut oil oleic acid peroxide, tertiary peroxide, stearic acid peroxide, stearic acid = peroxide

22

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The preferred catalyst is a catalyst which is effective at moderately low temperatures, such as about 45-85 ° C.

In addition to the free-radical polymerization catalysts, the catalysts may include such materials which polymerize primarily by opening the epoxide group, such as the epoxy-terminated, copolymerizable, hydrophobic, macromolecular monomer. Such catalysts include p-toluenesulfonic acid, sulfuric acid, phosphoric acid, aluminum chloride, stannous chloride, ferric chloride, boron trifluoride, boron trifluoride-ethyl ether complex and iodine. It may be desirable to use a multistage polymerization process.

The amount of catalyst used depends on the type of catalyst system used and is generally from approx. 0.1 to approx. 10 parts by weight per 100 parts: monomer mixture and preferably ranges from approx. 0.1 to approx. 1 part by weight 100 parts. • monomer.

The copolymerization is generally carried out at a temperature of approx. room temperature to approx. 165 ° C. However, it is generally preferred to initiate the polymerization at a relatively low temperature, such as from ca. 40 ° C to approx. 85 ° C, and then increase the temperature to approx. 90 ° C to approx. 165 ° C as the reaction proceeds, and preferably 20 after most of the reaction has been completed. The most preferred initial temperature range for polymerization is between ca. 45 ° C and 70 ° C. The polymerization is usually carried out under self-generated pressure in a closed reaction vessel. However, any suitable means can be used to prevent substantial evaporation of any of the monomers.

The copolymerization is generally completed at approx. 4 to approx. 48 hours and preferably ends in approx. 6 to approx. 24 hours. Of course, it is understood that time and temperature are inversely related. That is, the temperature used at the upper end of the temperature range will produce polymerization processes which can be terminated at near the lower end of the time interval.

23

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r

After the copolymerization, the graft copolymer can be cured by any suitable means, if desired. However, due to the self-reinforcing and self-curing effect of the graft copolymers of the present invention, such post-curing is generally not necessary, except in applications where extreme strength is required. In the event that a post-curing reaction is desired, this may be carried out in a mold or mold cavity corresponding to the general or exact shape and / or size of the desired product. After the polymer is finished, including any post-cure, a solid, rigid and clear copolymer is obtained. The prepared product can then be swollen in a suitable liquid until equilibrium is reached or until a hydrogel containing the desired amount of liquid such as an aqueous liquid is reached. In addition, it should be noted that the hydrogels can be obtained by swelling the polymers in the hydrogel of the invention with water-soluble swelling agents instead of aqueous solutions. Some examples of water-soluble swelling agents include ethylene glycol, the liquid polyethylene glycols, the glycol esters of lactic acid, formamide, dimethylformamide, dimethyl sulfoxide and the like.

2q The copolymers of the hydrogel according to the invention, in addition to being formed in situ, can be processed by compression molding, extrusion molding or injection molding. It is also contemplated within the scope of the present invention that the copolymer can be applied as a coating to other substrate materials. In this case, the pod copolymers of the hydrogel of the invention are particularly useful since they contain both hydrophilic and hydrophobic groups. One or the other of these groups or both may be present with the coated substrate.

As stated in U.S.A. U.S. Patent No. 3,786,116 is the copolymerizable or reactive end group of the hydrophobic macromolecular monomer copolymerized with the second monomer, specially selected based on the relative reactivity ratios of the second monomer selected to form the hydrophilic, polymeric backbone.

Thus, the present invention provides a means for controlling the structure of the graft copolymer. More specifically, the control of the structure of the graft copolymer can be achieved by any or all of the following ways:

DK 151816 B

1) by determining the reactivity ratio of the copolymerizable, hydrophobic, macromolecular monomer to the other monomer during the copolymerization reaction, a pure graft copolymer free of contamination with homopolymers can be prepared; 2) by controlling the rates of monomer addition during the copolymerization of the copolymerizable, hydrophobic, macromolecular monomer, and the other comonomer, the distance between the side chains of the polymer structure can be controlled; and 3) the size of the seed chain can be predetermined and controlled at the anionic polymerization step in the preparation of the copolymerizable, hydrophobic, macromolecular monomer.

!

It will be apparent to those skilled in the art that by the appropriate choice of termination agents, all copolymerization mechanisms can be utilized in the preparation of the controlled, phase-separated graft copolymers.

Of fundamental importance is the fact that the location of the side chain in the polymeric backbone depends on the terminal group of the macromolecular monomer and the second copolymerizable monomer. Thus, the distribution of the side chain polymer along the backbone polymer is controlled by the reactivity ratio of the respective monomers.

As stated above, according to the invention, the copolymerizable hydrophobic macromolecular monomers with the monomers forming the hydrophilic polymeric backbone in a predictable manner, as determined by relative reactivity ratio.

It can be shown that the present copolymer equation: dM1 M1 „r1 mVm2 + 1p“ X η dir LirJ Mx, 2 ~ p + r

L Ir J

25 is simply reduced to the approximation: (2) 4 ^ π

dM r M

m Α * ν »· Ρλ7> δ 1 i η · π · ΰ7»? τηΩη · α4 · 1 βττώ τηηΊ olrtfl η λΔυι 4-υ »λ 4 * · ΐ 25 -1

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i i_

Thus, the copolymerizations of the macromolecular monomer (M1) with other monomers (M) are described only by r-values and compositions of monomer addition. Re-grouping of Equation (2) gives: t-7 \ "2 dM ^ / M ^ io conversion K5) r = —Ί -y = L --- r dM / M $ conversion M 2

The reactivity ratio r can be judged from a relatively low conversion sample from a single copolymerization experiment. The validity of this notion of predictable and controllable reactivity of the copolymerizable, hydrophobic, macromolecular monomer can thus be established. It has been found that the reactivity of commercially available monomers with the copolymerizable, hydrophobic, macromolecular monomers with different end groups correlates with available literature values for r-reactivity ratios.

Following the above procedures, graft copolymers having unique property combinations are prepared. These unique combinations of properties are made possible by the above-described method, which forces compatibility of otherwise incompatible polymeric segments. These incompatible segments segregate into phases of their own kind. Thus, in the case of the present seed copolymers having a hydrophilic polymeric backbone and a hydrophobic polymeric side chain, separate phases of the respective polymers are formed. The product morphology consists of a hydrophobic region which spreads into a hydrophilic polymer matrix. The hydrophobic regions are interconnected by water-soluble chain segments. The hydrophobic regions act as cross-links and provide the wet strength of the water-swollen polymeric backbone. The degree of swelling in water can be controlled by the amount and molecular weight of the copolymerized, hydrophobic, macromolecular monomer and by the composition of the water-soluble or hydrophilic polymeric backbone. An example type comprises a material wherein the hydrophilic backbone is composed of a 5/95 acrylic acid / ethyl acrylate to 100/0 acrylic acid / ethyl acrylate and a methacrylate terminated polystyrene having a molecular weight in the range of about 10,000 to approx. 35eOOO and a weight range of 20 to approx. 80i of the total product. This product can be swollen with water to obtain a useful hydrogel.

_I I

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26

The dissolution properties of the graft polymers in the hydrogel of the invention differ from "random" copolymers. While in the case of a random copolymer, dissolution properties can be treated as if they were for a new polymer composed of a single monomer unit, the graft copolymers in the hydrogel of the invention contain elements of the properties of the incoming homopolymer chains. As soon as the interaction between the two different polymer chains becomes dominant, incompatibility and phase separation become the rule.

For example, when a graft copolymer consisting of the water-soluble and water-insoluble component chains is added to a compounded latex, interaction between the polymeric thickener and latex particles, pigments or clay takes place, and the polymeric thickener molecules collapse. Since two homopolymer chains are incompatible, the hydrophobic chains are assembled to form a microgel particle. The Elok-15 culture progresses rapidly to form large aggregates, and finally a network is formed where all particles are bonded together by latex thickener molecules, where microgel particles from the hydrophobic portion of the thickener molecules act as crosslinking points. Using polymeric materials such as industrial thickening agents, flocculants, etc., the most effective structures are block or graft copolymers containing two incompatible homopolymer chains, i.e. that one is hydrophilic and the other is hydrophobic. The hydrophilic portion of the molecule solubilizes the hydrophobic portion to render the entire molecule water (or alkali) soluble. However, when the thickener is added to a compounded latex, interaction between the thickener and latex particles, clay or pigments takes place and the graft copolymer reduces its water solubility. The hydrophobic portion of the molecule becomes water-insoluble and aggregates to form a microgel as it is incompatible with another portion of the molecule.

The invention is further explained in the following examples.

In each case, all materials must be clean and care must be taken to keep the reacted mixtures dry and free of contaminants. All parts and percentages are parts by weight and percentages, with 35 unless otherwise explicitly stated.

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27 I I_

Example 1 (Preparation of hydrophobic, macromolecular monomer) I

preparation of a polystyrene terminated with allyl chloride.

A stainless steel container is charged with 76.56 parts of A.O.S. grade benzene (thiophene free) which has previously been dried by lime 5 molecular sieves and calcium hydride. The vessel is heated to 40 ° G and 0.015 parts of diphenylethylene is added to the reactor using a hypodermic syringe. A 12.1 $ solution of sec-butyllithium in hexane is added portionwise to the reactor until a permanent orange-yellow color is maintained, at which time an additional 0.885 parts (1.67 10 moles) of sec-butyllithium solution is added, followed by addition of 22.7 parts (218 moles) of styrene over a period of 44 minutes. The reactor temperature is maintained at 36-42 ° C. The reactive polystyrene is terminated by adding 0.127 parts of allyl chloride to the reaction mixture. The resulting polymer is precipitated by the addition of an α-olefin = 15 polystyrene benzene solution in methanol and the polymer precipitates out of solution. The cc-olefin-terminated polystyrene is dried in an air dryer with circulating atmosphere at 40-45 ° C and then in a fluidized layer to remove trace amounts of methanol. The methanol content after purification is 10 parts per million. The molecular weight of> 0 polymer determined by membrane phase osmometry is 15,400 (theoretically 13,000) and the molecular weight distribution is very narrow, i.e. that Mw / Mn is less than 1.05. The macromolecular monomer has the following structural formula: OH 30 H 2 (CH 3) CH-OH 2 CH - CH 2 -CH = CH 2 L o where n has such a value that the molecular weight of the polymer is 15,400.

Example 2 (Preparation of hydrophobic, macromolecular monomer) Preparation of poly (q-methylstyrene) completed with allyl chloride.

A solution of 472 g (4.0 mole) of α-methylstyrene in 2500 ml of tetrahydro = furan is treated dropwise with a 12 $ Ts solution of n-butyllithium in hexane until a persistent pink color. An additional 30 ml (0.383 mol) of this n-butyllithium solution is added, resulting in the development of a clear red color. The temperature of the mixture is then lowered 28

DK 151816B

to -80 ° C and after 30 minutes at this temperature 4.5 g (0.06 mol) of allyl chloride is added. The red color disappears almost immediately, indicating the termination of the reactive polymer. The resulting colorless solution is poured into methanol to precipitate the α-olefin-terminated poly (oc-methylstyrene), which by vapor phase osmometry is shown to have a numerically average molecular weight of 11,000 (theoretically 12,300), and the molecular weight distribution is very narrow, i.e.. that Mw / Mn is less than 1.05. The prepared macromolecular monomer has the following structural formula: CH * in 3 CH 5 CH 2 CH 2 CH 2 - J-CH 2 - c - ch 2 ch = ch 2 l 61 10 wherein n has such a value that the molecular weight of the polymer is 11,000.

Example 3 (Preparation of hydrophobic, macromolecular monomer)

Production of polystyrene completed with vinyl chloroacetate.

A solution of 1 drop of diphenylethylene in 2500 ml of cyclohexane at 40 ° C is treated portionwise with a 12 $ solution of sec-butyllithium in cyclohexane until a pink color persists, at which time another 18 ml is added ( 0.024 mol) sec-butyl = lithium followed by 312 g (3.0 mol) styrene. The temperature of the polymerization mixture is maintained at 40 ° C for 30 minutes. Then the reactive polystyrene is quenched by treatment with 8 ml (0.040 mol) of diphenylethylene and then terminated by treatment with 6 ml (0.05 mol) of vinyl chloroacetate. The resulting polymer is precipitated by adding the cyclohexane solution to methanol and the polymer is separated by filtration. Its numerically average molecular weight determined by vapor phase osmometry is 12,000 (theoretical 13,265) and the molecular weight distribution is very narrow, i.e. that Mw / Mn is less than 1.06. The macromolecular monomer produced has the following structural formula: r in 9? CH 3 CH 2 (CH 3) CH — CH 2 —CH - ch 2 —C — CH 2 COCH = ch 2 o in 6 wherein n has such a value that the molecular weight of the polymer is 12,000.

I I_ DK 151816 B.

29 ·

Example 4 (Preparation of Hydrophobic, Macromolecular Monomer)

Preparation of poly (q-methylstyrene) terminated with vinyl = chloroacetate.

A solution of 357 g (3.0 mole) of α-methylstyrene in 2500 ml of tetrahydrofuran is treated dropwise with a 12 $ solution of t-butyllithium in pentane until a pink color is persisted, then an additional 15.0 is added. ml (0.03 mol) of the t-butyllithium solution resulting in the development of a clear red color. The temperature of the mixture is then lowered to -80 ° C, and after 30 minutes at this temperature 10 5.6 ml of diphenylethylene are added. The resulting mixture is poured into 5.0 ml (0.04 mole) of vinyl chloroacetate and the poly (oc-methylstyrene) thus completed is precipitated with methanol and separated by filtration.

Its numerically average molecular weight determined by vapor phase osmometry is 14,280 (theoretical, 12,065) and the molecular weight distribution is very narrow. The macromolecular monomer produced has the following structural formula: chJ O 0

I 3 T II

CH 3 CH 2 (CH 5) OH - ch 2 - c --- ch 2 c - CH 2 COCH = ch 2 - 6 wherein n has such a value that the molecular weight of the polymer is 14,280.

Example 5 (Preparation of Hydrophobic, Macromolecular Monomer)

Preparation of a polystyrene terminated with vinyl-2-chloro => 0 ethyl ether,

A solution of 1 drop of diphenylethylene is mixed at 40 ° C dropwise with a 12 $ solution of t-butyllithium in pentane until a pink color persists, at which time an additional 30 ml (0.04 mole) of the t-butyllithium solution is added. followed by 312 g (3.0 mol), 5 styrene. The temperature of the polymerization mixture is maintained at 40 ° C for 30 minutes, after which the reactive polystyrene is terminated by treatment with 8 ml (0.08 mol) of vinyl-2-chloroethyl ether. The resulting polymer is precipitated by adding the benzene solution to methanol and the polymer is separated by filtration. Its numerically average 0 molecular weight determined by vapor phase osmometry is 7,200 (theoretical 7870),

DK 151816 B

And the molecular weight distribution is very narrow, i.e. that Mw / Mn is less than 1.06. The prepared macromolecular monomer has the following structural formula: (ch5) 3c - ch2 - ch - ch2ch2 and = ch2

L 6 -L

wherein n has such a value that the molecular weight of the polymer is 7200.

Example 6 (Preparation of hydrophobic, macromolecular monomer)

Production of polystyrene completed with epichlorohydrin.

A benzene solution of reactive polystyrene is prepared as set forth in Example 5 and terminated by treatment with 10 g (0.10 mol) of epichlorohydrin. The resulting finished polystyrene is precipitated with 10 methanol and separated by filtration. Its molecular weight determined by vapor phase osmometry is 8660 (theoretical 7757) and its numerically average molecular weight distribution is very narrow. The macromolecular monomer produced has the following structural formula: (ch3) 2 - c - ch 2 - ch - ch 2

Example 7 (Preparation of hydrophobic, macromolecular monomer)

Production of polystyrene terminated with methacrylyl chloride.

To a solution of 0.2 ml of diphenylethylene in 2500 ml of benzene is added dropwise a 12% solution of n-butyllithium in hexane until a light reddish-brown color persists. An additional 24 ml (0.051 mol) of this n-butyllithium solution is added and then 416 g (4.0 mol) of styrene is added, resulting in the development of an orange color. A temperature of 40 ° 0 is maintained throughout by external cooling and by controlling the rate at which the styrene is added. This temperature is maintained for a further 30 minutes after all the styrene has been added and the temperature is then lowered to 20 ° C, after which 4.4 g of I

DK 151816 B

Ethylene oxide (0.1 mole) is added, causing the solution to become colorless. The reactive polymer is then terminated by reaction with 10 ml (0.1 mole) of methacrylyl chloride. The resulting polymer has a numerical average molecular weight of 10,000 determined by vapor phase osmometry. The macromolecular monomer has the following structural formula: r-0

II

CH5CH2CH2CH2 - ch2 - CH - CH2CH20CC = CH2. o in k where n has such a value that the molecular weight of the polymer is 10,000.

Example 8 (Preparation of Hydrophobic, Macromolecular Monomer)

Preparation of polystyrene terminated with methacrylylohloride.

10 A stainless steel container is filled with 32 gallons of A.C.S. grade benzene (thiophene free) which had previously been dried using lime molecular sieves and calcium hydride. The reactor is heated to a temperature between 38 and 40 ° C and 10 ml of diphenylethylene is added to the reactor by means of a hypodermic syringe. An 11.4 $ solution of sec-butyllithium in hexane is added portionwise to the reactor until a permanent orange-yellow color (60 ml) is obtained, at which time an additional 1,562 kg of sec-butyllithium in hexane is added to the reactor. followed by the addition of 37,455 kg of purified styrene over a period of 1 hour and 40 minutes. The reactor temperature is maintained at 38-40 ° C. The 20 reactive polystyrene is quenched by the addition of 127.1 g of ethylene oxide and the reaction solution changes from a red-orange color to a yellow color. The resulting quenched reactive polystyrene is then reacted with 260 ml of methacrylylohloride and the solution changes to a very pale yellow color. The methacrylate-terminated polystyrene is precipitated by adding the polymer-benzene solution to methanol, after which the polymer precipitates out of the solution. The polymer is dried in an air dryer with circulating atmosphere at 40-45 ° C and then in a fluidized layer to remove traces of methanol. The molecular weight of the polymer determined by membrane phase osmometry is 13,400, and the 30 molecular weight distribution is very narrow, i.e. that Mw / Mn is less than 1.05.

DK 151816B ·., 32

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Example 9 (Preparation of Hydrophobic, Macromolecular Monomer)

Preparation of polystyrene, Aer is completed with maleic anhydride.

A stainless steel container is filled with 2.5 liters of A.C.S. grade benzene (thiophene free) which has previously been dried using Linde-5 molecular sieves and calcium hydride. The reactor is heated to 40 ° C and 0.2 ml of diphenylethylene is added to the reactor by means of a hypodermic syringe. A 12.1% solution of sec-butyllithium in hexane is added portionwise to the reactor until a permanent orange-yellow color is obtained (0.7 ml), at which time an additional 22.3 is added to the XO. ml of sec-butyllithium solution followed by the addition of 421.7 g of styrene over a period of 16 minutes. The reactor temperature is maintained at 40-45 ° C. 5 minutes after the styrene addition is complete, ethylene oxide is added intermittently beneath the surface of a lecture flask until the solution is water-white.

X5 1 hour after the ethylene oxide addition is complete, 20.55 ml of maleic anhydride benzene solution (the maleic anhydride solution was prepared by dissolving 84 g of maleic anhydride in 550 g of purified benzene) is added to the quenched reactive polymer. One hour after the addition of the maleic anhydride solution, the reactor contents are discharged and precipitated in methanol. The polystyrene terminated with maleic acid halves had a molecular weight of approx. 14-000 determined by gel penetration chromatography. The polymerizable macromolecular monomer has the following structural formula:

.--.ISLAND

II

SEC. butyl - CH2-CH - CH2CH20C

A, \ h L U Jn ||

CH

HOC ^

II

0

Example 10 (Preparation of hydrophobic, macromolecular monomer) Preparation of polybutadiene terminated with allyl chloride.

C.P. grade 1,3-butadiene (99% purity) is condensed and collected in 1-pint soda bottles. These bottles had been oven-baked for 4 hours at 150 ° C, purged with nitrogen under cooling and then encapsulated with an I-33

DK151816B

perforated metal capsule using butyl rubber and polyethylene foil linings. These bottles containing the hutadiene are stored at -10 ° C with a nitrogen pressure height (10 psi) in a laboratory freezer before use. Hexane solvent is charged to the reactors and heated to 50 ° C followed by the addition of 0.2 ml of diphenylethylene by syringe. Sec-butyllithium is added dropwise to the reactor via a syringe until the red diphenylethylene anion color lasts for at least 10-15 minutes. The reactor temperature is lowered to 0 ° C and 528.0 g of butadiene is charged to the polymerization reactor followed by L0 addition of 17.4 ml (0.02187 mole) of a 12 $ sec. Butyllithium solution in hexane when half the amount of butadiene is reached. has been added to the reactor. The butadiene is polymerized for 18 hours in hexane at 50 ° C.

After the polymerization, 400 ml portions of the solution of the anionic polybutadiene solution in the reactor L5 are transferred to encapsulated bottles under nitrogen pressure. Allyl chloride (0.48 ml, 0.00588 mol) is injected into each of the bottles. The jellyfish are clamped in water baths at temperatures of 50 ° C and 70 ° C for a period of time between 1 hour and up to 24 hours. The samples in each of the bottles were short-stopped with methanol and ionol solution and analyzed by gel penetration chromatography. Each of the samples is water-white, and the analysis of the gel permeation chromatography scanners shows that each of the samples had a narrow molecular weight distribution.

Multiple comparative tests were performed in bottles coming from the same amount of reactive polybutadiene which was quenched with 2-chloro = 25 butane (0.4 ml, 0.00376 mol) as the terminating agent. The resulting polymers, which were terminated with 2-chlorobutane, were yellow in color and, after standing for a period of 24 hours at 70 ° C, were found to have a wide molecular weight distribution, as evidenced by the gel penetration chromatography scanner. It will be seen that the reaction and reaction product of 2-chlorobutane with anionic polybutadiene is different from the reaction and reaction product of allyl chloride and anionic polybutadiene.

Example 11 (Preparation of hydrophobic, macromolecular monomer).

Preparation of methacrylate terminated polyisoprene.

A 3.8 liter Chemoglas bowl reactor is charged with 2.5 liters of purified heptane, which has previously been dried by lime-molecular sieves and 34

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calcium chloride, followed by the addition of 0.2 ml diphenylethylene as indicator and the reactor sterilized by dropwise addition of a solution of tert-butyllithium ($ 12 in hexane) until the characteristic pale yellow color is maintained. The reactor is heated to 5 to 40 ° C and 19.9 ml (0.025 mol) of a 12 $ solution of tert.-butyllithium in hexane is injected into the reactor by a hypodermic syringe, followed by the addition of 551.4 g (4.86 mol) of isoprene. The mixture is allowed to stand for 1 hour at 40 ° C and 0.15 mol of ethylene oxide is charged to the reactor to quench the reactive 20 polyisoprene. The quenched reactive polyisoprene is maintained at 40 ° C for 40 minutes, then 0.041 moles of methacrylyl chloride are charged to the reactor to terminate the quenched reactive polymer. The mixture is kept for 15 minutes at 40 ° C followed by removal of the methane solvent by vacuum stripping. Based on the gel-permeation chromatography scanners for polystyrene, the molecular weight of the methacrylate-terminated polyisoprene by gel permeation chromatography was approx. 10,000 (theoretically 15,000). The methacrylate-terminated polyisoprene macromolecular monomer has a structural formula as follows: -i 0,, li (CH 5) 3 - c - ch 2 ^ ch 2 - ch 2ch 2oc - c = ch 2 / c = \ k L ° y H Jn 5 Example 1 12 (Preparation of hydrophobic, macromolecular monomer) Preparation of q-olefin-terminated polyisoprene.

A 3.8 liter Chemoglas bowl reactor is charged with 2.5 liters of purified heptane, which has previously been dried using a Linde molecular sieve and calcium hydride, followed by the addition of 0.2 ml of diphenylethylene 25 as indicator. The reactor and solvent are sterilized by dropwise addition of a solution of tertiary butyllithium ($ 12 in hexane) until the characteristic light yellow color is maintained. The reactor is heated to 40 ° C and 19.05 ml (0.02426 mol) of tertiary butyl lithium solution is injected into the reactor by a hypodermic syringe followed by the addition of 515.5 g (4.65 mol) of isoprene. The polymerization is allowed to proceed at 50 ° C for 66 minutes, at which point 2.0 ml (0.02451 mole) of allyle hydrochloride is added.

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rid of the reactive polyisoprene. The completed polyiso = I

The prene is kept at 50 ° C for 38 minutes, after which the polymer is removed from the re

the actor to be used for copolymerization conversions. Poly- | the miter was analyzed by gel permeation chromatography 5 and had a very narrow molecular weight distribution, i.e. an Hw / Mn of less than 1.06. The theoretical molecular weight of the polymer is 13,000.

The polymerizable macromolecular monomer has a structural formula as follows: (ch3) 3 - C - ch2v ^ οη2 - ch2ch = ch2 _oh3 / \ h J n

Example 13 (Preparation of hydrophobic, macromolecular monomer) Preparation of a polystyrene macromolecular monomer interrupted with butadiene and terminated with allyl chloride.

2.5 liters of benzene (thiophene-free) are charged to the reactor and heated to 40 ° C. 0.2 ml of diphenylethylene is added as indicator and the reactor is sterilized by dropwise addition of a 12 $ solution of sec-15 butyllithium until an orange-red color is maintained. At this time, an additional 18 ml (0.024 mole) of sec-butyllithium ($ 12 in hexane) solution is added followed by 416 g (4.0 mole) of styrene. The temperature of the polymerization mixture is maintained at 40 ° C for 5 minutes.

The reactive polystyrene with butadiene is then quenched by re-bubbling of butadiene gas in the reactor until the color of the solution changes from dark red to orange. The reactive polymer is terminated by treatment with 4.1 ml (0.05 mole) of allyl chloride. The macromolecular monomer thus prepared is precipitated with methanol and separated by filtration. Its numerically average molecular weight judged from gel penetration chromatography is 25,000 (theoretically 18,000) and the molecular weight distribution is very narrow. The prepared macromolecular monomer has the following structural formula: CEUCH / p-CH-GEd-CH --- CH 2 CH = CH CIL · CH $ CH = 0Ho 3 2 I 2 IL 2 2 Jm 2 2 °% LO -1 where m is equal to 1 or 2.

3.6 DK 151816 B 4

Example 14 (Preparation of Graft Copolymer)

Preparation of a graft copolymer with a hydrophilic polymeric polyacrylic acid backbone and hydrophilic polymeric polystyrene side chains.

60 g of a polystyrene terminated with vinyl-2-chloroethyl ethylene, 5 as prepared in Example 5, and having a molecular weight of approx. 8000 and a very narrow molecular weight distribution, so that the ratio Mw / Mn is less than approx. 1.06, "was dissolved in 240 g of acrylic acid and 50 g of tetrahydrofuran (TUF) in a 2-liter resin container. An additional 500 g of THF was placed in the 2-liter resin container, and then 0.6 g The container was heated to 65 ° C and the polymerization allowed to proceed for 2 hours. After polymerization, 300 g of distilled water was added to the resin holder and the THF amount distilled off. 25 Example 15 (Preparation of pod copolymer)

Preparation of a graft copolymer with a hydrophilic polymeric polyacrylic acid backbone and hydrophobic polymeric polystyrene side chains.

4 g Triton X-100 was dissolved in 500 g distilled water and placed in 20 a Waring mixer. 30 g of tertiary hutyl polystyrene vinyl ether, readily prepared as in Example 5, dissolved in 60 g of henzene and the solution added to the Waring mixer containing the Triton X-100 solution under heavy shear to produce a stable dispersion. The dispersion was poured onto a 2-liter resin tank equipped with a stirrer and a condenser, and the container was purged with nitrogen for 1 hour. It was then heated to 65 ° C and 240 g of acrylic acid were added (pH neutralized to 8.0 with ammonium hydroxide). 1 g of henzoyl peroxide was added to the resin holder and polymerization was carried out at 69 ° C for 3 hours.

The polymer was recovered as set forth in Examples 14, 37

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Example 16 (Preparation of Graft Copolymer) I

Preparation of a graft copolymer with a hydrophilic polymeric poly = I

acrylic acid backbone and hydrophobic polymeric polystyrene side chains.

18 g of Triton X-405 (or 26 g of $ 70 solid Triton X-405) were dissolved in 5,300 g of water and the pH was adjusted to 8 with ammonium hydroxide, whereupon the solution was placed in a Waring mixer. 30 g of the tertiary butyl polystyrene vinyl ether prepared as in Example 5 was dissolved in 70 g of ethyl acrylate and the solution was added to the Waring mixer containing Triton X-405 solution under 10 strong shear to produce a stable dispersion. . The dispersion was charged to a 2-liter resin container equipped with a stirrer and a capacitor, and purged with nitrogen for 1 hour. The vessel was heated to 65 ° C and 0.1 g of ammonium persulfate was added. 200 g of ethyl acrylate and 2 $ 15 ammonium persulfate solution were added to the polymerization vessel over a 3-hour period and the polymerization was carried out at Ted 65-67 ° C. The polymeric backbone was made hydrophilic by hydrolyzing the acrylic ester groups with alkali under heat. The resulting hydrophilic-hydrophobic polymer was recovered in the manner described in the foregoing Examples.

Example 17 (Preparation of Hydrogels)

Datex thickening with graft polymer having a hydrophilic polymeric polyacrylic acid backbone and hydrophobic polymeric polystyrene side chains.

Three seed copolymers composed of $ 80 polymeric polyacrylic acid backbones and $ 20 polymeric polystyrene side chains prepared as set forth in the preceding examples were tested as a latex thickener. The size of the polystyrene side chains was as follows: Sample A (G30),

Mn equals 1000; Sample B (G32), Mn equal to 4000; and sample C (G33),

Mn equals 8000. The seed copolymers were tested as follows.

To 300 g samples of Wica Latex 7035 ($ 50 solid) were added 0.3 g, 0.6 g and 1.2 g of the hydrophilic graft copolymer (solid basis), and the viscosity was measured by a Brookfield LVT. viscosimeter (spindle # 3, 12 rpm). The results of this experiment were as follows:

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Brookfield viscosity (centipoise) Amount added Sample Sample Sample copolymer iA (Q30) Β (032) C (Q33) nothing 1400 1430 1410 0.3 g 3100 3380 3550 0.6 g 4200 4900 5600 1.2 g 6500 7000 7500

As can be seen from the above data, the graft copolymers of the invention act as excellent thickeners for latexes due to the presence of both hydrophilic and hydrophobic polymeric segments. It was found that the polymeric side chains, which have a uniform molecular weight distribution, contributed to the total capacity in terms of forming a stable latex. It is also seen that the higher molecular weight polymeric side chains increase the total thickening capacity. This is due to the fact that the higher molecular weight polymeric side chains, i.e. over approx. 2000, recalls the properties 10 of a polystyrene polymer and better phase separation occurs when the polymeric side chains have a higher molecular weight.

Example 18 (Preparation of Graft Copolymer)

Preparation of hydrophilic polymeric polyvinyl alcohol backbone graft copolymers having hydrophobic polymeric polystyrene side chains.

15 g of the purified, copolymerizable, hydrophobic, macromolecular monomer having a vinyl ether group, which monomer is prepared by the procedure of Example 5 (the macromolecular monomer was prepared in the same way, except that sec-butyllithium was used as initiator, and the polymer had a molecular weight of 2080 as well as a Mw / Mn ratio of less than about 1.1), was copolymerized with 240 g of vinyl acetate in benzene using benzoyl peroxide as catalyst. The polyvinyl acetate-styrene graft copolymer (G-26) thus prepared was hydrolyzed to polyvinyl alcohol-styrene graft copolymer in a 50/50 methanol / benzene mixture using sodium methoxide as a catalyst. The resulting polymer was washed with methanol, vacuum dried and then extracted with benzene. Analysis of the extracted copolymer showed that there were

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formed a copolymer. The saponified product was molded to a film I to determine its water resistance in comparison to

trade in polyvinyl alcohol. Each of the foils was applied to I

glass and dipped in water at room temperature overnight. For simple visual observation, it was clear that the water resistance of the copolymers was much improved over the water resistance of the control polyvinyl alcohol.

Example 19 (Preparation of Graft Copolymer)

Production of hydrophilic polymeric polyvinyl alcohol backbone graft = 10 copolymers having hydrophobic polymeric polystyrene side chains.

A latex copolymerization reaction was performed by adding 0.4 g of sodium dodecyl sulfate to 85 g of water with stirring. 15 g of the methacrylate terminated polystyrene prepared as set forth in Example 8 was added followed by the addition of 30 g of vinyl acetate. 0.15 g of benzoyl peroxide was added and the polymerization was carried out for 6 hours at 40-50 ° C. After polymerization, the copolymer was stirred in 100 ml of methanol and 10 g of sodium methoxide was added to the solution over a 20 minute period. The solution was refluxed for 10 minutes and the polymer was washed twice with iso = 20 propanol and dried at 70 ° C under vacuum. The solubility of the hydrolyzed product was investigated using various solvents. The copolymer was slightly soluble in DMSO, but insoluble in toluene, tetrahydrofuran, benzene and cresol. Films made from the copolymer were transparent and exhibited good elongation and excellent wet strength.

Example 20 (Preparation of Graft Copolymer)

Preparation of hydrophilic polymeric methacrylate backbone podeco = polymers having hydrophobic polymeric polystyrene side chains.

75 parts of a methacrylate-terminated polystyrene, prepared as set forth in Example 7 and with a uniform or narrow molecular weight distribution, were mixed with 125 parts of hydroxyethyl methacrylate and the polymerization was initiated with 0.4 parts of tertiary butyl peroctate as polymerization catalyst. The polymerization of the material was carried out by initially heating the mixture to ca. 50 ° C for 8 hours. Po

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The polymerization "was then completed by heating for 1 hour at 90 ° C and then by heating for an additional 1 hour at 120 ° C. After the polymerization was complete, a clear, solid and rigid copolymer was obtained. The polymer" was contacted with a physiological saline solution until it was in a state of osmotic equilibrium with the physiological saline solution. The hydrogel film thus obtained was clear, flexible and resilient.

Example 21 (Preparation of Graft Copolymer)

Preparation of a graft copolymer with a hydrophilic polymeric poly (N, N-dimethylacrylamide) backbone and hydrophobic polymeric polystyrene side chains.

40 g of the purified highly functional methacrylate-terminated polystyrene prepared as set forth in Example 8 (molecular weight 13,400 and a Mw / Mn ratio of less than 1.05) and 60 g of N, 3-dimethyl = 15 acrylamide were obtained. dissolved in 150 g of benzene. The mixture was mixed on a shaker to obtain a homogeneous solution. 0.12 g of Y (YAZO) polymerization initiator was added and the contents transferred to a "one quart" polymerization bottle. The contents were purged with nitrogen and sealed, followed by further nitrogen purification. The polymerization bottle was placed on a shaker in a water bath at 60 ° C for 19 1/2 hours, followed by a final polymerization temperature of 85 ° C for 2 hours. The resulting copolymer was a clear, very viscous liquid. 250 g of benzene was added to the viscous liquid copolymer to make it less viscous. The weight of the solvent and copolymer was 465 g, of which $ 20.9 was solid (95.4 g solid) to give a copolymer yield of $ 95.4.

Films of the copolymer were cast by drawing the benzene copolymer solution onto glass sheets using a drawbar. The films 30 were optically clear. The coated sheets were dipped in distilled water and the resulting wet films were hard and remained clear. The swelling ratio of the foils was 2.2 g water per day. g copolymer. The wet sheets had a tensile strength of 870 psi and an extension of $ 100. The films were tested for water vapor transmission (WVT) using the ASTM test method E96-63T (B), and the WT value for the wet films was 1100 g / 24 h / m.

i I_ DK 151816B> 41 - ·.

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Gel penetration chromatography analysis of the copolymer showed that no unreacted, hydrophobic, macromolecular monomer was present. In The fact that the copolymer did not dissolve when dipped in water, | and the high strength of the wet films are indicative of the hydrophobic, 5-polymer side chains acting as physical cross-links to the normal, water-soluble poly (N, N-dimethylacrylamide).

The copolymer mentioned above was inverted in water and judged for properties in terms of water vapor transmission; wet copolymer = foil when measured for WVT was 2000 g / 24 h 2 m 2, showing its utility as a semi-permeable membrane.

Example 22 (Preparation of Graft Copolymer)

Preparation of a graft copolymer with hydrophilic polymeric poly (IT, N-dimethylacrylamide) backbone and hydrophobic polymeric polystyrene = side chains.

15 parts of a methacrylate-terminated polystyrene prepared by the procedure described in Example 8 (the methacrylate-terminated λ polystyrene had a molecular weight of 12,100 and a Mw / Sa ratio of ® less than about 1.06 as determined by permeation chromatography analysis), was dissolved in a mixture of 90 parts of ΙΤ, ΙΤ-dimethylacrylamide and 20,900 parts of benzene. The mixture was placed on a shaker until a homogeneous solution was obtained, then 0.1 part AIBlf was added and the solution was filled into a "one quart" polymerization bottle which was purified with nitrogen and encapsulated. After a further purification of the encapsulated system with nitrogen, the polymerization mixture was placed on a shaker in hot water at 67 ° C and the polymerization allowed to continue for 12 hours. After polymerization, the copolymer was recovered by precipitation in hexane followed by filtration and drying. The copolymer was a clear, viscous solution which had excellent wet strength properties when dipped in water.

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Example 23 (Preparation of Graft Copolymer)

Preparation of a graft copolymer with hydrophilic polymeric poly (N, N-dime thylacrylamide) base, splicing and hydrophobic polymeric polystyrene = side chains.

(5 parts of a methacrylate terminated polystyrene prepared according to the procedure set forth in Example 8 (the methacrylate terminated polystyrene had a molecular weight of 12,700 and a Mw / Mn ratio of less than about 1.05 "as determined by gel permeation chromatography analysis) , dissolved in 90 parts of Ν, dim-dimethyl acrylamide, 5 parts of calcium-10 cium stearate dispersed in the comonomer mixture, and 200 parts of hepatane and 0.1 part of AIBN were added to the comonomer mixture with rapid stirring. A polymerized container was subjected to a further nitrogen purification to purify the system. The polymerization was carried out by placing the polymerization container on a shaker in a hot water bath at 67 ° C, and polymerization was allowed. to continue for 12 hours The copolymer was obtained in the form of a fine powder and this was easily filtered and dried. The recovery of the copolymer was extremely successful due to the application of the non-aqueous emulsion polymerization technique. Analysis of the product by gel penetration chromatography revealed that no unreacted methacrylate-terminated polystyrene was present. The copolymer had excellent wet strength when immersed in water. The copolymer was also useful for preparing a polyvinyl chloride polyol blend. In this way, various poly mixtures were prepared by dry mixing 40-60 parts by weight of the copolymer with 60-40 parts by weight of polyvinyl chloride. The dry mixtures were subjected to shear action on a mill at elevated temperatures to obtain foils having excellent properties with respect to water vapor transmission. For a further description of mixtures of polymers of N, N-dialkylacrylamides with polyvinyl chloride resins, reference is made to U.S.A. Patent Application Serial No. 559,284. "

As a particular example of a poly blend, 33.3 parts of the copolymer described in the foregoing dry blend with 70 parts of polyvinyl = chloride (Vygen 110) and 70 parts of dioctyl phthalate (EOP). A dry blended mixture was placed on a rubber grinder at 150 ° C for 8 minutes.

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The blended components melted very lightly to form a smooth, clear I and transparent film. After mixing and exposing the mixture I

for heavy shear, rated a 10 mil thick film | properties in terms of water vapor transmission and water absorption.

ISLAND

The poly mixture had a water vapor transmission of 200 g / 24 h / m and absorbed 5.8 $ moisture in 18 hours at 85 $ relative humidity.

In comparison, a similar mixture made with a homopolymer of Ν, ΪΤ-dimethylacrylamide with the softened polymer β of vinyl chloride had a water vapor transmission of 75 g / 24 h / n and absorbed $ 4.5 moisture in 18 h at 85 $ relative humidity. It was quite clear that in addition to the improved physical properties, the hydrophobic polystyrene side chains improved the processing of the poly mixture, and this was due to the solubility of the polystyrene side chains in the dioctyl phthalate. In other words, the side chains improved the melting theology imparted to poly (F, F-dimethylacrylamide) by these seed chains.

Example 24 (Preparation of Graft Copolymer)

Preparation of a graft copolymer of hydrophilic polymeric poly (hydroxy = ethyl methacrylate) backbone and hydrophobic polymeric polyisoprene side chains.

50 parts (based on dry solids basis) of the methacrylate-terminated polyisoprene prepared as set forth in Example 11 (the methacrylate-terminated polyisoprene had a molecular weight of 10,000 and a Mw / Ma ratio of less than 1.1 as determined by gel permeation chromatography) , in heptane was mixed with 100 parts of hydroxyethyl methacrylate in a 1 liter polymerization reactor. The comonomer mixture was purified with nitrogen and copolymerized by adding 0.2 parts of AIBU polymerization initiator at a temperature of 67 ° C over a period of 16 hours. The resulting copolymer was a clear, viscous solution. The clear copolymer solution was placed in a Form 44

DK 151816B

and subjected to gamma irradiation for 20 minutes. The copolymer "was then immersed in physiological saline. The wet copolymer had an excellent wet strength which added to the fact that the hydrophilic backbone held together by the hydrophobic side chains linked by the radiation crosslinking. thus enhanced by a cross-linked hydrophobic region structure chemically bonded to the hydrophilic matrix phase.

The hydrophilic-hydrophobic graft copolymers of the hydrogel of the invention unexpectedly have improved physical properties (e.g., tensile strength, wet strength, elongation, etc.) when in their hydrated state. Hydrophilic polymers must generally be cross-linked with a chemical cross-linking agent to achieve these improved physical properties. However, the aforementioned novel graft copolymers provide in a unique way a thermally labile, physical crosslinking which serves to anchor the polymeric backbone segments, and also provides a "filler effect", thus increasing the modulus and tensile strength of the final polymer. When the graft copolymer is heated to a temperature higher than Tg for the polymeric side chain (90-100 ° C for polystyrene), the regions become fluid and flow under pressure so that they are in fact thermoplastic. As the graft copolymer is cooled, the regions are restored and the graft copolymer regains properties as a cross-linked hydrophilic polymer.

The addition of an aqueous liquid merely acts to plasticize the hydrophilic polymer without dissolving the entire copolymer material. The graft copolymers can be formed into hydrogels by immersing them in an aqueous liquid (water or physiological saline solution, etc.). The amount of aqueous liquid can vary over a wide range, depending on the composition of the graft copolymer, i.e. that amount of the polymeric side chains of the graft copolymer. According to the invention, the amount of the aqueous liquid will range from approx. 10 weight $ to approx. 95% by weight of the graft copolymer, preferably 45-80% by weight. Even when large amounts of aqueous fluids are present in the hydrogels of the invention, these are capable of retaining their shape, making them useful for making contact lenses, body implants and the like. The formation of the hydrogel by lowering the copolymer in an aqueous liquid which is collected in the copolymer in the form of tiny droplets filling microscopic polymer

Claims (8)

1, Hydrogel having utility as a medical hydrogel and consisting of a chemically bonded, phase-separated, self-cured, thermoplastic, water-insoluble, water-swellable graft copolymer and from ca. 10% by weight to approx. 95% by weight of water by weight of the copolymer, which copolymer is produced by copolymerization of a hydrophobic macromolecular monomer and a hydrophilic copolymerizable monomer, characterized in that the copolymer is made by graft copolymerization, the polymer backbone of the graft copolymer consists of polymerized units of said hydrophilic copolymerizable monomer that the hydrophobic macromolecular honor monomer has the formula R 2 z X 1 where R is the lower alkyl group, Z is repeating monomer units of a vinyl aromatic compound, with up to 12 carbon atoms and / or of a DK 151816 B 'conjugated diene with 4-8 carbon atoms, n is an integer of such value that the molecular weight of the polymer is between 2,000 and 50,000, and X is a polymerizable group, optionally attached to a "protecting agent" for the polymer, at the same time the hydrophilic backbone is made up of units of acrylic acid, a hydroxyalkyl acrylate, a dialkyl acrylamide or vinyl acetate, be macromolecular monomer has a uniform molecular weight distribution that its Mw / ifo ratio does not substantially exceed approx. 1.1, which macromolecular monomer is further characterized in that it has no more than one copolymerizable group per cell. linear polymer or copolymer chain, the copolymerization having occurred between the copolymerizable end group of the hydrophobic macromolecular monomer and the copolymerizable hydrophilic monomer, and the linear polymeric side chain copolymer copolymerized to the polymeric backbone separated by at least about 20 continuous monomer units in said hydrophilic polymeric backbone, the distribution of the side chains along the backbone and copolymerization being achieved by the reactivity ratio of the copolymerizable end group of said hydrophobic macromolecular monomer to said hydrophilic copolymeric monomer. Hydrogel according to claim 1, characterized in that the copolymerizable monomer forming the hydrophilic polymer backbone is a water-soluble vinyl monomer containing at least one nitrogen atom in the molecule. Hydrogel according to claim 1, characterized in that the copolymerizable monomer after graft copolymerization is hydrolyzed to form a polyvinyl alcohol backbone. Hydrogel according to claim 1, characterized in that the copolymerizable hydrophobic macromolecular monomer has the structural formula: R 'R - CH2-C - CH2CH2OCH = CH2 6- DK 1851816Β wherein R is lower alkyl, R' is either hydrogen or lower alkyl and n is a positive integer having a size such that the molecular weight of the polymer is in the range of from 5,000 to about 5,000. 50,000. Hydrogel according to claim, characterized in that the co = 5 polymerizable hydrophobic macromolecular monomer has the structural formula - O CH 3 CH 2 (CH 3) CH - CH 2 - CH - CH 2 CH 2 O-CC = CH 2 An 0 * 3 where n is such a positive integer, that the molecular weight of the polymer is in the range of approx. 5,000 to approx. 50,000. Hydrogel according to claim i, characterized in that the co-polymerizable hydrophobic macromolecular monomer has the structural formula "~ 0 tt CH3CH2 (CH3) CH - CH2 - C = CH-CH2 --- ch2ch2oc-c = CH2 CH3 n CH3 Wherein n is such a positive integer that the molecular weight of the polymer is in the range of about 5,000 to 50,000. Process for the preparation of a hydrogel according to claim 1, characterized in that graft copolymer is obtained from approx. 1 to approx. 95% by weight of a hydrophobic, polymerizable macromonomer of the formula R [cf. 50,000 and a substantially uniform molecular weight distribution, so that its Mw / Mn ratio is at least approx. 1.1 and further with only one polymerizable group per linear polymer or copolymer chain, which polymerizable group exists at the end of the chain, and from ca. 99 to approx. 5% by weight of at least one hydrophilic copolymerizable monomer selected from acrylic acid, a hydroxyalkyl acrylate, a dialkylacrylamide or vinyl acetate, which hydrophilic copolymerizable monomers form the polymer backbone of the graft copolymer, and which copolymerizable hydrophobic macromolecular monomeric monomeric monomeric monomeric monomer wherein the graft copolymer linear polymer side chains are copolymerized to the main chain polymer via the polymerizable end group of the macromolecular monomer, wherein the graft copolymer linear polymer side chains copolymerized to the polymer head chain are separated by at least about 20 uninterrupted repeating monomer units in said polymer main chain, and the copolymerization and distribution of the side chains along the polymer main chain is regulated by the relative reactivity ratio of the polymerizable end group of the hydrophobic macromolecular monomer to the hydrophilic copolymerizable comonomer and bringing the hydrophilic polymer into the copolymer. contact with an aqueous liquid to form a hydrogel containing from ca. 10 to approx. 95% by weight of the water-containing liquid, calculated in relation to the weight of the graft copolymer. Process according to claim 7, characterized in that the copolymerizable compound is vinyl acetate which is rendered hydrophilic by saponification after graft copolymerization.