Novel Degradable Polymer Networks Containing Acetal Components and Well-Defined Backbones

Abstract

A novel copolymer network was successfully prepared by combining the reversible addition–fragmentation chain-transfer polymerization (RAFT) and addition reaction between hydroxyl and vinyloxy groups. 2-Hydroxyethyl methacrylate (HEMA) and methyl methacrylate (MMA) were copolymerized in 1,4-dioxane with 2,2′-azobisisobutyronitrile as initiator and 2-(ethoxycarbonyl)prop-2-yl dithiobenzoate as a RAFT agent. The molecular weight of poly(HEMA-co-MMA) was well controlled and the polydispersity was low. The hydroxyl group from the HEMA unit in the copolymer underwent an addition reaction with 1,4-cyclohexanedimethanol divinyl ether in the presence of pyridinium p-toluenesulfonate, generating a copolymer network with an acetal component in the crosslinking segment. The crosslinking time depended on the molar ratio of HEMA and MMA in the poly(HEMA-co-MMA). After being treated in strong acid, the copolymer network was able to be degraded owing to the acetal structure, but the backbone chains of poly(HEMA-co-MMA) remained intact.