Near-monodisperse, catalytically active, imidazole-containing homooligomers: Synthesis by group transfer polymerization and solution characterization

Oligomers covering degrees of polymerization up to 23 of 2-(1-imidazolyl)et hyl methacrylate (ImEMA) were synthesized by group transfer polymerization (GTP) in propylene carbonate and tetrahydrofuran (THF). While GTP proceeds smoothly in propylene carbonate, polymerization in THF is accompanied by ol igomer precipitation. The molecular weights (MWs) and molecular weight dist ributions (MWDs) of the oligomers were obtained by gel permeation chromatog raphy (GPC) using acidic aqueous sodium nitrate as the eluent. Good control over the MW and small polydispersity indices (PDIs) were measured for the oligomers prepared in propylene carbonate but not in THF. The oligomers wer e evaluated for their ability to hydrolyze 4-nitrophenyl acetate in aqueous solution. The hydrolytic activity increased with oligomer MW. The oligomer concentration- and substrate concentration-dependencies of the initial hyd rolysis rate were both found to be approximately first order. The hydrolyti c activity increased with an increase in pH, manifesting the enhanced nucle ophilicity and pronounced hydrophobicity of the unprotonated form of the re peating units. (C) 1999 John Wiley & Sons, Inc.