DETERMINATION OF SOLUBILITY PARAMETER OF POLY(N-VINYL-2-PYRROLIDON ETHYLENEGLYCOLDIMETHACRYLATE) GELS BY SWELLING MEASUREMENTS/

The solubility parameters of pure Poly(n-vinyl 2-pyrrolidone) (PVP) an d Poly(n-vinyl 2-pyrrolidone/ethylene glycol dimethacrylate)P(VP/EGDMA ) hydrogels have been evaluated via swelling experiments. Twenty solve nts with various solubility parameters have been used in the swelling experiments. Considering the limitations of using the approach as deve loped by Gee, we have applied an asymmetric double sigmodial equation for locating the peak maxima in swelling curves. The solubility parame ters are evaluated via this new approach. The solubility parameter of pure PVP is determined to be 11.38 +/- 0.11 Kb. The incorporation of E GDMA into the gel system slightly reduced the solubility parameter. Th e influence of relative amount of EGDMA on the solubility parameter wa s investigated, and evaluated values compared with literature and theo retically determined solubility values by group contribution values of van Krevelen, Small, and Hoy. (C) 1998 John Wiley & Sons, Inc.