Thermosensitive copolymer synthesized by controlled living radical polymerization: Phase behavior of diblock copolymers of poly(N-isopropyl acrylamide) families

摘要

In this study, we prepared a series of thermosensitive polymers with low polydispersity index (PDI) values by nitroxide-mediated controlled radical polymerization (NMRP) with 2,2,6,6-tetramethyl-1-piperdinyloxy nitroxide (TEMPO) as a stable nitroxide-free radical. Poly(N-isopropyl acrylamide) (PNIPAAm)-block-poly(N-tert-butyl acrylamide) (PNTBA) was successfully synthesized, first, through polymerization with N-isopropyl acrylamide to obtain the reactive polymer PNIPAAm-TEMPO and, second, through polymerization by the addition of N-tert-butyl acrylamide (NTBA). The added molar fraction of NTBA during the second polymerization was adjusted accordingly to obtain the final polymerization product, a thermosensitive polymer (PNIPAAm-block-PNTBA), which had a targeted lower critical solution temperature (LCST). The result shows that the synthesis method used in this study effectively controlled the formation of the polymer to obtain a low PDI. The thermosensitive block copolymer, PNIPAAm-b-PNTBA (molar ratio = 9:1), with LCSTs in the range 27.7-39.8 degrees C, was obtained through controlled living radical polymerization with PNIPAAm-TEMPO. Specifically, the 5 wt % aqueous solution of PNIPAAm-b-PNTBA (molar ratio = 9:1) had an LCST of 37.4 degrees C; this was close to body temperature, 37 degrees C. The 5 wt % aqueous solution of PNIPAAm-b-PNTBA (molar ratio 9:1) showed potential for use in biomedical applications. (c) 2015 Wiley Periodicals, Inc.