Hydrophilic modification of silicone elastomer films: Thermal, mechanical andtheophylline permeability properties

The improvement of the hydrophilicity of silicone rubber (SR) is sought inmany biomedical applications. In thepresent work, we have prepared neat films coming from condensation-type SR, modified either through blendingor end-linking reaction with lowmolecularweight poly(ethylene glycol) (PEG). The filmswere studied withrespect to theirwater uptake capacity, stability of embedment of ethylenoxy moieties, and mechanical and thermalproperties. Subsequently, we prepared drug-loaded films with theophylline, a relatively hydrophilic modeldrug, and studied the release performance of these systems. Results on neat films showed that blending increasessignificantly the overall water uptake of the films and, at the same time, has a limited detrimental effect on theirmechanical properties. On the other hand, end-linked films loaded with theophylline exhibited betterrate-controlling properties in vitro, due to better dispersion of the sorbed water.