Properties of PVA-AA cross-linked HEMA-based hydrogels

Poly(HEMA) hydrogel is usually prepared by using 1,1,1-trimethylol propane trimethacrylate and ethylene glycol dimethacrylate as the crosslinkers. Ano ther method using PVA-AA (polyvinyl alcohol partially esterified with acryl oyl chloride) as the cross linker is reported here. Two hydrogels, co-A1H9 and co-A2H8, were prepared by the polymerization of HEMA in the presence of 10% and 20% PVA-AA, respectively. The presence of PVA-AA reduced the water content from 32% to 25% in the resultant copolymer, whereas T-g did not ch ange significantly. Co-A1H9 had an elastic modulus of 6.3 Mpa, which is muc h higher than 3.9 MPa and 3.7 MPa for poly(HEMA) and co-A2H8, respectively. The interfacial energies of poly(HEMA), co-A1H9 and co-A2H8 were calculate d to be 0.52. 0.65 and 0.71 dyne/cm(2), respectively, whereas the fractiona l polarities of these three hydrogels were all about 0.74. Thus a HEMA-base d hydrogel with surface properties similar to poly(HEMA) but with stronger mechanical strength was successfully prepared. This copolymeric hydrogel co uld provide a choice other than the conventionally cross linked poly(HEMA) for various applications.