In a nitrogen atmosphere the UV irradiation of thin PVC films (ca. 0.1 mm thick) containing vinyltri(isopropoxy)silane results in a grafting reaction. By appropriate choice of conditions, dehydrochlorination can be kept to a minimum while up to 60% gel content is realized. Reaction of the pendent alkoxy groups, either with HCl byproduct or subsequent hydrolysis by exposure to water, results in the formation of Si-O-Si bonds that serve as chemical crosslinks, Although the addition of photosensitizers favors the grafting reactions at short exposure times, the ultimate level of crosslinking is greatly diminished by their presence.