Self-reinforcing hydrogels comprised of hydrophobic methyl methacrylate macromers copolymerised with either N-vinyl-2-pyrrolidone or 2-hydroxyethyl acrylate

Methyl methacrylate macromers have been synthesised by catalytic chain tran sfer polymerization with M-n values ranging from 565 to 25 392. These macro mers were subsequently copolymerized with either 2-hydroxyethyl acrylate or N-vinyl-2-pyrrolidone, in bulk, by gamma-radiation to yield xerogel materi als. Copolymerization was confirmed by NMR analyses and by subsequent aqueo us extraction of the resultant copolymers. The xerogels containing 2-hydrox yethyl acrylate and macromers below 10 000 (M-n) molecular weight yielded p opcorn polymers. All other xerogel materials were transparent. On swelling in deionised water, compositions containing 2-hydroxyethyl acrylate became white and opaque indicating phase segregation. In contrast all of the hydro gels based on N-vinyl-2-pyrrolidone retained transparency. Hydrogels were f ormed that had significantly higher Young's moduli than hydrogels based on random copolymers of equivalent composition.