Poly(acrylic acid) modified PEG hydrogels

Poly(ethylene glycol) [PEG] hydrogels were synthesized using UV photopolymerization of PEG 575 diacrylate. The swelling of these gels can be controlled by varying the ratio of PEG 575 DA to water in the precursor solution. In the range of 1-10% PEG we observed swelling ratios ranging from 11 down to approximately 5 with the gel brittleness increasing dramatically over this range. We observed that at low pH, 5100 Mw poly(acrylic acid) [PAA] can rapidly infiltrate the PEG gels affecting both their total mass and their swell properties. When immersed in high pH water where PAA deprotonates, the PAA is released over a period of several weeks.