Preparation of controlled release systems by free-radical UV polymerizations in the presence of a drug.

UV free-radical polymerization techniques are often used to synthesize hydrogels for controlled release applications. Numerous techniques exist for immobilizing drugs or solutes in the gel. This work focuses on the entrapment of solute in a hydrogel by conducting a photopolymerization in the presence of the monomer and the solute. A kinetic gelation model has been developed to examine the effect of the solute material on the polymerization process and the ensuing network structure. Kinetic experiments have also been conducted of the polymerization of poly(ethylene glycol) methacrylate in the presence of theophylline. It was found that the presence of the solute led to a more heterogeneous network with numerous microgel regions present. The effect of the size of the solute on the polymerization was also investigated.