Poly(N-isopropylacrylamide)/poly[(N-acetylimino)ethylene] thermosensitive block and graft copolymers

Block and graft copolymers with poly(N-isopropylacrylamide) and poly[(N-acetylimino)ethylenel (PNAI) sequences were synthesized via PNAI derivatives (macroinitiators or macromers). The polymerization yields for block copolymers synthesized in ethanol, using the PNAI macroinitiator, were low (<10%), except where photochemical polymerization was applied. By contrast, for the copolymerizations of N-isopropylacrylamide with the PNAI macromers, performed in alcoholic solution, quite high polymerization yields, around 80-90%, were reached. H-1-NMR and IR spectral and differential scanning calorimeter thermal data confirmed the copolymer formation. Thermosensitivity of the copolymers was investigated by means of turbidimetric technique as a function of their nature, average molecular weight and composition. It was found that the length of the chain of the PNAI macromer and the content in hydrophilic PNAI units of the resulted copolymer affected this behavior. (C) 2003 Elsevier Science Ltd. All rights reserved.