CROSS-LINKED HYDROGEL COPOLYMER

1494641 Cross-linked hydrogel copolymer SMITH & NEPHEW RESEARCH Ltd 4 July 1975 [4 July 1974 28 April 1975] 29757/74 and 17586/75 Heading C3P A lightly cross-linked hydrogel copolymeric material capable of an uptake of physiological saline of 65-85% by weight based on the total weight of the gel is formed from (1) at least one water soluble n-vinyl lactam and (2) as a comonomer, not more than 15 mole per cent, based on the total moles of (1) and (2) of (1) and (2), of at least one compound of the formula wherein X is NH or O; R<SP>1</SP> is H or alkyl-(C 1-4 ); and R<SP>2</SP> is either (a) a substituted or unsubstituted aryl group or (b) an alkyl group (C 1-6 ), substituted by at least one substituted or unsubstituted aryl group and/or at least one substituted or unsubstituted aryloxy group or (c) a hydroxyalkyl group (C 1-6 ) further substituted. The specific examples describe the preparation of copolymers of (1) vinyl pyrrolidone and as (2) one of the benzyl, phenoxyethyl, phenethyl, methoxybenzyl, naphthyl, 4-phenylphenyl, 4-benzyl-phenyl, 4-t-butyl phenyl esters of methacrylic acid. Specific cross-linking agents used in the examples are allyl methacrylate, 3-allyloxy-2-hydroxy-propyl methacrylate, 2-allyloxy ethyl methacrylate, 2-(2- allyloxy ethoxy)-ethyl methacrylate and 2-(2- allyloxy-ethoxy ethoxy)-ethyl methacrylate.