Dual roles of alkyl alcohols as syndiotactic-specificity inducers and accelerators in the radical polymerization of N-isopropylacrylamide and some properties of syndiotactic poly(N-isopropylacrylamide)

摘要

The effects of simple alkyl alcohols on the radical polymerization of N-iso-propylacrylamide in toluene at low temperatures were investigated. We succeeded in the induction of syndiotactic specificity and the acceleration of polymerization reactions at the same time by adding simple alkyl alcohols such as 3-methyl-3-pentanol (3Me3PenOH) to N-isopropylacrylamide polymerizations. The dyad syndiotacticity increased with a decrease in the temperature and an increase in the bulkiness of the added alcohol and reached up to 71% at -60 degrees C in the presence of 3Me3PenOH. With the assistance of NMR analysis, it was revealed that the alcohol compounds played dual roles in this polymerization system; an alcohol compound coordinating to the N-H proton induced syndiotactic specificity, and that hydrogen-bonded to the C=O oxygen accelerated the polymerization reaction. The effect of syndiotacticity on the properties of poly(N-isopropylacrylamide)s was also examined in some detail. (c) 2006 Wiley Periodicals, Inc.