SYNTHESIS AND FUNCTIONALITIES OF POLY(N-VINYLALKYLAMIDE) .5. CONTROL OF A LOWER CRITICAL SOLUTION TEMPERATURE OF POLY(N-VINYLALKYLAMIDE)

N-vinyl-n -butyramide (NVBA), N-vinylisovaleramide (NVIVA), and N-viny l-n-valeramide (NVVA), which are N-vinylalkylamides with different alk yl groups were synthesized and their solution behavior in a polymeric form was examined. Copolymers of N-vinylisobutyramide (NVIBA) with N-v inylacetamide (NVA), NVIBA with NVVA, and NVVA with NVA were prepared by the solution polymerization to control the LCSTs. The resultant pol yNVBA showed a lower critical solution temperature (LCST) sharply at 3 2 degrees C, but polyN-vinylisovaleramide (polyNVIVA) and polyN-vinyl- n-valeramide (polyNVVA) that have n-butyl and isobutyl groups, respect ively, an their side chains were insoluble even in cold water. The wat er solubility of the resulting polymers was found to vary, depending o n the molecular shapes as well as the side chain length of the alkyl g roups in question. The copolymers consisting of NVVA, NVIBA, and NVA i n water showed LCSTs sharply between 10 and 90 degrees C, depending on changes in their comonomer content. It was found that the changes in LCST that are caused by the incorporation of comonomers are due to cha nges in the overall hydrophilicity of the polymer. (C) 1997 John Wiley & Sons, Inc.