HYDROGELS BASED ON GRAFT-COPOLYMERIZATION OF HEMA BMA MIXTURES ONTO SOLUBLE GELATIN - SWELLING BEHAVIOR

Graft copolymerization of mixtures of 2-hydroxyethyl methacrylate (HEM A) with n-butyl methacrylate (BMA) onto soluble gelatin was attempted using eerie ammonium nitrate as initiator, with the aim of obtaining h ydrogels based on two different components: a natural polymer and a sy nthetic polymer. Other hydrogels were formed by simultaneous graft cop olymerization and crosslinking using ethylene glycol dimethacrylate (E GDMA) as crosslinking agent. Per cent grafting (%G), per cent grafting efficiency (%GE) and per cent total conversion (%C-t) were calculated for various feed compositions and for various EGDMA concentrations. E quilibrium water content of the hydrogels was investigated as a functi on of the hydrophilicity of the polymers and the degree of crosslinkin g agent, and the influence of pH on the swelling behaviour of the hydr ogels was determined. It was observed that the equilibrium water conte nt increased as the percentage of hydrophilic monomer in the copolymer increased, and the swelling values increased with pH changes from the acid to the alkaline range.