Hydrophilic copolymers based on N-[tris(hydroxymethyl)methyl]-acrylamide, processes for their preparation, aqueous gels of said copolymers and their use as ion exchangers

Claim 1

Tridimensional cross-linked random copolymers, insoluble in water, containing in copolymerized form: (a) 25% to 98% by weight of N-[tris(hydroxymethyl)methyl]acrylamide or N-[tris(hydroxymethyl)methyl]methacrylamide or a mixture of these two compounds; (b) 2% to 50% by weight of one or more monomers possessing two or several polymerizable ethylenic double bonds and free of anionic or cationic functional groups; and (c) 0.1% to 50% by weight of one or more monomers corresponding to the formula: ##STR8## in which R 1 is a hydrogen atom, an alkyl group containing 1 to 4 carbon atoms, an SO 3 H or an SO 3 M group, M indicating an alkali metal, X 1 is a single bond, an oxygen atom or a --CH 2 --, ##STR9## --SO--, --SO 2 -- or p-phenylene group, p, p', q and q' are whole numbers from 0 to 4, Z and Z' are oxygen atoms or sulfur atoms or ##STR10## --SO--, --SO 2 --, --CH═N--, --NH--SO 2 --, --CHOH--, --C.tbd.C-- or ##STR11## groups, R 2 indicating a hydrogen atom or a methyl or methoxy group, and Y represents a monosubstituted amino, disubstituted amino, pyrimidinyl, guanidyl or purinyl group, salified or not, a quaternary ammonium, SO 3 H or SO 3 M group, M being an alkali metal.