Self-reinforcing hydrogels comprised of hydrophobic methyl methacrylate macromers copolymerized with N,N-dimethylacrylamide

Methyl methacrylate macromers were synthesized by a catalytic chain-transfer polymerization, with number-average molecular weight values ranging from 600 to 26,000. These macromers subsequently were copolymerized with dimethyl acrylamide in bulk by γ radiation to yield transparent xerogel materials. The copolymerization was confirmed by NMR analyses and by subsequent aqueous extractions of the resultant copolymers. On swelling in deionized water, hydrogels were formed that had significantly higher Young's moduli than hydrogels based on statistical methyl methacrylate/dimethyl acrylamide copolymers of equivalent composition. If macromers of high molecular weight were used, phase separation occurred, resulting in opaque hydrogel compositions.