RAFT synthesis of acrylic polymers containing diol or dioxane groups

In this study, an acrylate monomer containing two hydroxyl groups, 2,2-bis(hydroxymethyl)butyl acrylate (HBA), was successfully synthesized by acidic hydrolysis of the monomer precursor, (5-ethyl-2,2-dimethyl-1,3-dioxane-5-yl)methyl acrylate (EDMA), which was prepared by esterification reaction between 2,2-dimethyl-5-ethyl-5-hydroxymethyl-1,3-dioxane and acryloyl chloride. Subsequently, poly(HBA) containing pendant diol group was prepared either by direct reversible addition-fragmentation chain transfer (RAFT) polymerization of HBA or by RAFT polymerization of EDMA, followed by deprotection. The RAFT polymerization of both monomers was performed in dioxane using 2-(ethylthiocarbonothioylthio)-2-methyl propanoic acid (EMP) as the RAFT agent and 2,2′-azobis(isobutyronitrile) (AIBN) as the initiator. Kinetic studies demonstrated that the polymerization process of both monomers followed pseudo first-order kinetics with respect to the monomer concentrations. The molecular weight of the resulting polymer increased linearly with monomer conversion, while a low polydispersity was maintained throughout.