Polymer networks containing degradable polyacetal segments

Telechelic poly(1,3-dioxolane)s (polyDXL) with methacrylate end groups have been synthesized by cationic ring-opening polymerization of DXL, carried out in the presence of methylenebis(oxyethyl methacrylate) as an end blocker. If the initiator concentration is negligible compared with the end-blocker concentration, the molecular weight of the thus obtained polyDXL is governed by the ratio of reacted monomer to reacted end blocker. Radical copolymerization of the alpha,omega-bis(methacrylate)-terminated polyDXL leads to the formation of polymer networks in which the polyDXL acts as a polymeric cross-linking agent. The resulting materials are insoluble in any solvent and swell in good solvents for the corresponding linear polymers. Since the ceiling temperature of the polyDXL is low, the thus obtained networks can be de-cross-linked under mild conditions by treatment with a trace of cationic initiator. In the presence of alcohols, the degradation is retarded and acid-catalyzed hydrolysis of the networks failed completely. However, the thermal stability of the acid-treated networks is markedly lower than that of untreated samples