A POTASSIUM ALCOHOLATE-INITIATED POLYMERIZATION OF 2-(TRIALKYLSILOXYETHYL) METHACRYLATE

Anionic polymerization of 2-(t-butyldimethylsiloxyethyl) methacrylate (ProHEMA) was performed with potassium ethanolate as an initiator in t etrahydrofuran. It was found that the potassium ethanolate-initiated p olymerization of ProHEMA proceeds smoothly at ambient temperature to 9 0% monomer conversion. The polymerization was initiated by the additio n of ethanolate at the double bond in ProHEMA. It is considered that c omplexation of potassium cation with the ProHEMA molecule increased th e nucleophilicity of the oxonium anion to increase the initiation abil ity. Based on the C-13 n.m.r. analysis, poly(ProHEMA) obtained with po tassium ethanolate was syndiotactic rich in microstructure. This is al so explained by the bulky counter cation complexed with monomer molecu les, which controls monomer insertion around the growing centre. This polymerization method can be applied to a synthesis of an end-function alized poly(2-hydroxyethyl methacrylate) (poly(HEMA)). (C) 1997 Elsevi er Science Ltd.