Preparation of DrugContaining EVA/Silica Composite Films and Their in vitro Sustained Release Performance

Drug-releasing composites containing ethylene-vinyl acetate copolymer (EVA) /silica were prepared via sol-gel route. The structure and hydrophilic/hydrophobic property of composites were studied. Aspirin was used as a model drug and the effect of silica content on the sustained release behaviors of polymer was studied. Results show that silica can be homogeneously dispersed in the copolymers by solgel method and the sustained release performance of EVA is improved. When the mass fraction of silica is 10%, the silica particle size is about 2—4 μm, and the films exhibit the best sustained release performance with sustained time exceeding 72 h. The drug release behavior of the composite samples fits well with the Fickian diffusion model.