Ceskoslovenska Akademie Ved

Artur Stoy

Vladimir Stoy

Jiri Zima

Renata Urbanova

Otto Wichterle

Miroslav Stol

Jaroslav Prokop

Josef Kucera

Jaroslav Kalal

Vaclav Jungr

Substantially water-insoluble, water-swellable crosslinked hydrogels are prepared by polymerizing monomeric material consisting predominantly of acrylonitrile in aqueous salt solution containing zinc chloride as the main component, in absence of added crosslinking agents. The concentration of acrylonitrile is in the range of about 20 to about 40% by weight, related to the weight of the polymerization batch as a whole 100%. The process is carried out by partially hydrolyzing the primary gel thus obtained which consists of polyacrylonitrile plasticized with the aqueous salt solution, whereafter the zinc ions are removed from the gel by treating it with a dilute aqueous solution of at least one electrolyte forming an insoluble precipitate therewith. The partial hydrolysis may be carried out either by increasing the acidity of the solution or temperature or both. Insoluble crosslinked hydrogels are prepared in the form of shaped articles, preferably in either closed or open molds, or in raw castings such as sheets or plates from which the final shaped articles can be manufactured by mechanical processes such as by cutting.

Shaped articles from insoluble hydrogels and method of manufacturing same

There is disclosed a method of producing hydrogel tubes comprising partially hydrolyzing an acrylonitrile-containing polymer in an inorganic acidic solvent solution at temperature of about -10.degree. to 50.degree. C., extruding said hydrolyzed polymer solution through a circular nozzle into an aqueous coagulating bath, the same or similar coagulating bath simultaneously being fed through a central tube or pin of the nozzle. Preferably, the surface of the tube is made very slippery in wet condition, by treating it with chemical agents causing either a further hydrolysis or other reaction leading to carboxylic, sulfonic or sulfuric groups, or an esterification with polyols such as glycerol, glycols or polyvinyl alcohol, preferably with simultaneous sulfonation or sulfuration.

Method for manufacturing hydrogel tubes

The invention relates to a method of manufacturing shaped articles from crystalline or quasi-crystalline acrylonitrile polymers and copolymers, said method consisting in cooling down a solution of said polymer or copolymer in a mixture containing from 50 to 99.5% by weight of a solvent and from 0.5 to 50% by weight of a precipitant to a temperature below the gelation point of the solution until the same gelatinizes, without changing its composition, to the desired shape, whereafter the solvent is removed from the shaped thermoreversible gel thus obtained at temperatures lower than the gelation point of the solution, preferably using a liquid precipitant of polyacrylonitrile miscible with the solvent. It is advantageous to remove the solvent at a temperature which is at least 10.degree. C. lower than the gelation temperature of the polymer solution used. The shaping can be carried out in any convenient way, e.g. using a stationary or rotating mold. Beads, spheres, filaments and foils can be shaped without any mold in the usual way. The method is also suitable for coating surfaces.

Method of manufacturing shaped articles from crystalline acrylonitrile

A method of preparing cross-linked hydrogels in the form of shaped articles, insoluble in any solvent but swellable in water and in aqueous liquids is provided. The method comprises polymerizing acrylonitrile alone or with a minor amount up to 15% by weight of monoethylenically unsaturated monomers copolymerizable with acrylonitrile under conditions of radical polymerization in concentrated, i.e. 50 to 72% nitric acid in absence of any added chain-transfer and cross-linking agents, said monomer or monomers being used in concentrations making possible cross-linking by chain transfer onto the monomer, i.e. in concentrations ranging from 15 to 50%, preferably from 25 to 40% by weight, at temperatures ranging from 0.degree. to 50.degree. C., preferably from 5.degree. to 20.degree. C. The polymerization is carried out in a mold. The lyogel thus obtained is then kept within the same temperature range until the desired swelling capacity in water is reached, and nitric acid is removed by washing the casting in water or in aqueous liquids.

Method of preparing cross-linked hydrogels

A method of preparing cross-linked hydrogels in the form of shaped articles, insoluble in any solvent but swellable in water and in aqueous liquids, is provided. The method comprises polymerizing acrylonitrile alone or with a minor amount up to 15% by weight of monoethylenically unsaturated monomers copolymerizable with acrylonitrile under conditions of radical polymerization in concentrated, i.e. 50 to 72%, nitric acid in the absence of any added chain-transfer and cross-linking agents, said monomer or monomers being used in concentrations making possible cross-linking by chain transfer onto the monomer, i.e. in concentrations ranging from 15 to 50%, preferably from 25 to 40% by weight, at temperatures ranging from 0.degree. to 50.degree. C, preferably from 5.degree. to 20.degree. C. The polymerization is carried out in a mold. The lyogel thus obtained is then kept within the same temperature range until the desired swelling capacity in water is reached, and the nitric acid is removed by washing the casting in water or in aqueous liquids.

Method of preparing shaped articles from cross-linked hydrogels

The invention relates to a new type of soft contact lens from a hydrophilic, swelled copolymer, with high swelling capacity, high permeability for oxygen, comparatively high strength and low modulus of elasticity, said characteristics making the lens suitable for permanent wearing. The lens contains, at swelling equilibrium with water at 20.degree. C, from about 50 to about 95% by weight of water, preferably from about 70 to about 90%, and consists of a multiblock copolymer of acrylonitrile with acrylamide, containing, if desired, a minor amount of other monomer units, not exceeding 20 molar percent. The swelled hydrogel contains two distinct but inseparable phases, one of them being polyacrylonitrile detectable by X-ray analysis, the other being amorphous highly solvated hydrophilic polymer containing predominantly acrylamide units.

Soft contact lens from a macromolecular block copolymer

The invention relates to a new method for manufacturing shaped articles from multi-block copolymers of acrylonitrile with acrylamide and/or acrylic acid, using hot pressure molding, preferably in swelled condition.

Method for manufacturing shaped articles from multi-block copolymers

The invention relates to surgical tubular devices, such as catheters, tracheal or gastric intubation or sounding tubes, tubes for removal of tracheal or pulmonary secretions, and cyctoscopes designed to be temporarily introduced into cavities of living body and consisting of entirely or partially of a hydrophilic copolymer of acrylonitrile with either acrylamide or acrylic acid and, if desired, with a small amount of other co-monomers. The copolymers are swellable in water and aqueous solutions. In the swelled condition they are pliable, elastic and strong. Their properties can be changed by changing the degree of hydrolysis, if the copolymer was prepared by partial hydrolysis of polyacrylonitrile, or by changing the content of hydrophilic units, if the copolymer was obtained by copolymerization of a monomer mixture. The outer layer or surface layer of the part to be introduced into the cavities of living body such as the larynx, trachea, urethra, etc., contains neutralized anions in side-substituents such as carboxylic, sulphonic, sulphuric or phosphoric groups attached to the copolymer main chain by covalent bonds. The part expected to be exposed to the atmosphere during the application to the patient is permanently protected against drying by a layer of a polymer or copolymer impermeable for water and water vapors.

Hydrophilic surgical tubular device

A method for the preparation of a hydrophilic acrylonitrile-containing polymer comprising admixing a solution of said polymer in 47% to 75%, preferably 50 to 72% concentrated HNO.sub.3, with solid particles of a substance insoluble in said acid solution and soluble in water, aqueous solutions of said substance being operative to precipitate said polymer from said HNO.sub.3, shaping the mixture of the dissolved polymer with said solid substance to a desired physical shape, coagulating said shaped polymer in an aqueous medium and washing said solid particles out from the coagulated polymer, and articles made therefrom. The added solid substance either may react with nitric acid forming a water-soluble nitrate, or it may remain in the mixture unchanged.

Method for the preparation of hydrophilic spongy gels

The tendon prosthesis of the invention consists of a core formed of from a synthetic, preferably hydrophilic linear polymer oriented substantially in the direction of the main longitudinal axis of the prosthesis, having a tensile strength exceeding 100 kg/cm.sup.2 and an elastic elongation of 8 - 50 percent, preferably 12 - 25 % of the resting length, and a sheath consisting of one or more layers of a hydrophilic, substantially non-oriented, physically or covalently crosslinked polymer with an equal or higher elastic elongation and an approximately equal or higher hydrophilicity than that of said core. The material of the core and particularly that of the sheath are permanently compatible with living tissue.

Tendon prosthesis

Solutions of polymers or copolymers containing up to 100% of acrylonitrile units and from 0 to 50 mol percent of units of one or more comonomers copolymerizable with acrylonitrile into nitric acid-soluble polymers is wet spun in a coagulating bath containing a constant surplus of neutralizing agents in an amount ranging from about 0.05 to about 5% by weight which neutralizing agents are sufficient to convert the nitric acid into nitrates and to make the filaments leaving the coagulating bath free of nitric acid. The coagulating bath is maintained at a temperature at least about 5.degree. C above the temperature at which the solution of the same concentration is saturated with respect to its nitrate content. The concentration of the coagulating bath is kept constant during the wet spinning by withdrawing a part of the bath equimolar to the amount of nitric acid introduced therein by the wet spinning, adding a neutralizing agent to the bath at a rate at which the nitric acid is introduced into the bath and replacing the water lost from the bath during the withdrawing of the portion thereof. The filament fibers are concommitantly formed by washing, stretching, heat stabilizing and drying the material as it leaves the bath, together with the formation of nitrates by treating the withdrawn portion of the bath in conventional manner to recover in solid form the nitrates found in the withdrawn bath.

Method of simultaneously manufacturing acrylic fibers and nitrates

There is disclosed a method of preparing hydrophilic copolymers of acrylonitrile by initially polymerizing acrylonitrile with about 0.01 to about 30% by weight of a monomer selected from the group consisting of acrylamide; methacrylamide; monomers of the formula CH.sub.2 =CRCONHR.sup.1 wherein R is hydrogen or methyl and R.sup.1 is hydrogen, methyl or ethyl; N,N-dialkylacrylamides and methacrylamides and N-alkylol amides, thereafter subjecting said copolymer to hydrolysis by an aqueous acidic solvent for the monomers or swelling agent for the polymer comprising at least one compound selected from the group consisting of nitric acid, sulfuric acid, phosphoric acid, formic acid, zinc chloride and zinc chloride/HCl mixtures and subsequent isolating the product thus formed by removal of the acidic hydrolytic agent therefrom. The products thereof possess such properties as high tensile strength and high swelling capacity and they are accordingly suitable for the production of fibers, membranes, tubing and the like.

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Prague, Czechia

Artur Stoy