Synthesis and characterization of well-defined diblock and triblock copolymers of poly(N-isopropylacrylamide) and poly(ethylene oxide)

Well-defined diblock and triblock copolymers composed of poly(N-isopropylacrylamide) (PNIPAM) and poly(ethylene oxide) (PEO) were successfully synthesized through the reversible addition-fragmentation chain transfer polymerization of N-isopropylacrylamide (NIPAM) with PEO capped with one or two dithiobenzoyl groups as a macrotransfer agent. H-1 NMR, Fourier transform infrared, and gel permeation chromatography instruments were used to characterize the block copolymers obtained. The results showed that the diblock and triblock copolymers had well-defined structures and narrow molecular weight distributions (weight-average molecular weight/number-average molecular weight < 1.2), and the molecular weight of the PNIPAM block in the diblock and triblock copolymers could be controlled by the initial molar ratio of NIPAM to dithiobenzoate-terminated PEO and the NIPAM conversion. (C) 2004 Wiley Periodicals, Inc.