Abstract: Stable three dimensional hydrogels which absorb water, but are insoluble in water, and are particularly useful for the making of soft contact lenses, are prepared by reacting a water insoluble polyvinyl resin which contains reactive hydroxyl groups in its polymer chain, with a di- or poly-basic acid anhydride, to thereby introduce pendant carboxyl groups into the polymer chain, followed by treatment of the thus obtained carboxylated polymer to effect a limited amount of crosslinking thereof whereby a sparingly crosslinked hydrophilic polymer is obtained which when immersed in water absorbs water and swells to form a hydrogel, which does not dissolve in water.

Abstract: Novel cationic hydrogels, containing basic (cationic) groups in their molecular structure, and processes for their preparation are described. These novel hydrogels are three-dimensional polymer networks, having good water permeability and mechanical properties, and are obtained by simultaneous polymerization and crosslinking, in the presence of a polymerization catalyst, such as an organic peroxide, azobisisobutyronitrile or other free radical polymerization catalyst, of a mixture of (a) hydroxyalkyl acrylate or methacrylate, (b) a cationic monomer -- usually an ester of acrylic or methacrylic acid with an amino alcohol, the terminal amino group of which may be quaternized, such as dimethylaminoethyl methacrylate or acrylate and the quaternized derivatives thereof, and (c) a cross-linking agent, such as glycol diacrylate or dimethacrylate; if desired there may also be present (d) one or more additional monomers, usually an acrylic monomer such as an alkyl acrylate or methacrylate, acrylamides etc.

Abstract: Novel anionic hydrogels, containing acidic groups in their molecular structure, and processes for their preparation are described. These novel hydrogels are stable three-dimensional polymer networks, having good water permeability and mechanical properties, and are obtained by simultaneous polymerization and cross-linking, in the presence of a polymerization catalyst, such as an organic peroxide, azobisisobutyronitrile or other free radical polymerization catalyst, of a mixture of (a) hydroxyalkyl acrylate or methacrylate, (b) a polymerizable acidic monomer containing a sulfonic acid, sulfate or phosphate group in its molecular structure, such as sulfo-ethyl acrylate or methacrylate or a sulfate or phosphate derivative of a hydroxyalkyl- acrylate or methacrylate, and (c) a cross-linking agent, such as a glycol diacrylate or dimethacrylate; if desired there may also be present (d) one or more additional monomers, usually an acryloid monomer such as an alkyl acrylate or methacrylate, acrylamides etc.

Abstract: Novel cationic hydrogels, containing basic (cationic) groups in their molecular structure, and processes for their preparation are described. These novel hydrogels are three-dimensional polymer networks, having good water permeability and mechanical properties, and are obtained by simultaneous polymerization and crosslinking, in the presence of a polymerization catalyst, such as an organic peroxide, azobisisobutyronitrile or other free radical polymerization catalyst, of a mixture of (a) hydroxyalkyl acrylate or methacrylate, (b) a cationic monomer -- usually an ester of acrylic or methacrylic acid with an amino alcohol, the terminal amino group of which may be quaternized, such as dimethylaminoethyl methacrylate or acrylate and the quaternized derivatives thereof, and (c) a cross-linking agent, such as a glycol diacrylate or dimethacrylate; if desired there may also be present (d) one or more additional monomers, usually an acrylic monomer such as an alkyl acrylate or methacrylate, acrylamides etc.

Abstract: Novel cationic hydrogels, containing basic (cationic) groups in their molecular structure, and processes for their preparation are described. These novel hydrogels are stable, three-dimensional polymer networks, having good water permeability and mechanical properties.

Abstract: Novel anionic hydrogels, containing acidic groups, and their preparation are described. These novel hydrogels are stable, three-dimensional polymer networks, having good water permeability and mechanical properties.