Poly(methyl methacrylate), poly(vinyl acetate), polyacrylonitrile, polystyrene, and polyacrylamide were turned biodegradable by insertion of N-benzyl-4-vinylpyridinium chloride (BVP) into the main chain. For example, half-life of polyacrylonitrile that contained 3 mol% of BVP was 21 days. Half-life of polyacrylamide that contained I I mol% of BVP was 2.4 days. Half-life of polystyrene that contained 5 mol% of BVP was expected to be 30-40 days under the conditions where the amount of polymer was very small. Oligomers of vinyl compounds are biodegradable dissimilar to high molecular weight polymers, but they are not useful as polymeric materials. However, connection of oligomers by BVP produced biodegradable polymers. Such bridged polymers are different materials from conventional vinyl polymers, and the utility may be different to some extent, but they are substantially biodegradable. (c) 2007 Elsevier Ltd. All rights reserved.