Poly(benzyloxy ethyl methacrylate): preparation by free radical polymerization and by group transfer polymerization; with subsequent debenzylation to form poly(2-hydroxyethyl methacrylate)

Poly(benzyl methacrylate) (PBMA) was prepared by free radical polymerization (FRP), and by group transfer polymerization (GTP). Benzyloxy ethyl methacrylate (BOEMA) monomer was prepared by esterification of methacryloyl chloride with 2-benzyloxy ethanol. High vacuum and Schlenk based strategies for purification of BOEMA, prior to polymerization by GTP, were developed, and poly(2-benzyloxyethyl methacrylate) — PBOEMA — was prepared by FRP and by GTP. BOEMA proved much less reactive towards GTP than BMA. Supported palladium (Pd) based catalyst systems were acquired and prepared, and tested for efficacy as debenzylating agents for the benzyl ester substituents in PBMA — to form poly(methacrylic acid), and the benzyl ether substituents in PBOEMA — to form poly(2-hydroxyethyl methacrylate). It was found that PBMA could be debenzylated with greater efficiency than PBOEMA. As expected, the efficiency of debenzylation of these polymers on supported Pd catalysts was an inverse function of polymer molecular weight, and was considerably less than that expected for small molecule benzyl esters and benzyl ethers. A supported Pd catalyst, able to completely debenzylate high molecular weight PBOEMA, was developed. A Pd based catalyst system, prepared in situ as a polymer-supported colloid, proved to be equally effective as a debenzylating agent for high molecular weight PBOEMA.