Synthesis of Photocrosslinkable Polymers Using Abietic Acid and Their Characterization

Vinylbenzyl abietate (VBA) was synthesized by the reaction of 4-vinylbenzyl chloride with sodium abietate. VBA homopolymer and copolymers of VBA with methyl methacrylate (MMA) were prepared in benzene using azobisisobutyronitrile as an initiator. The compositions of the copolymers were measured with 1 H NMR. The monomer reactivity ratios were determined by Kelen-Tudos plot. The reactivity of VBA for the copolymerization was much larger than that of MMA. The glass transition temperature and the initial decomposition temperature of the homopolymer were higher than those of the copolymers. The polymers with the abietic acid moiety were crosslinked with UV irradiation. This result means that VBA can be a vinyl monomer for the preparation of photocrosslinkable polymers.