SWELLING PROPERTIES OF COPOLYMERIC HYDROGELS PREPARED BY GAMMA-IRRADIATION

Crosslinked xerogels in the form of rods have been prepared by the gamma -ray initiated copolymerization in vacuo of n-butyl acrylate (BA) with N-vinyl-2-pyrrolidone (VP) in the presence and absence of a crosslinking agent. Thin (about 0. 5 mm) disks were swollen in water at 21 degree C. The influences of dose, dose rate copolymer composition, and concentration of crosslinker on the water content, sol fraction, and extension ratio were investigated. A high level of reproducibility in properties of the hydrogels was obtained by numerous replicate experiments. The feasibility of scaling up the preparation to produce long (60 cm) xerogel rods of uniform properties has been demonstrated. For these copolymers, swelling in several common organic solvents generally exceeds that in water.