Synthesis and phase behavior of poly(N-isopropylacrylamide)-b-poly(L-lysine hydrochloride) and poly(N-isopropylacrylamide-co-acrylamide)-b-poly(L-lysine hydrochloride)

Abstract

The synthesis of poly(N-isopropylacrylamide)-b-poly(L-lysine) and poly(N- isopropylacrylamide-co-acrylamide)-b-poly(L-lysine) copolymers was accomplished by combining atom transfer radical polymerization (ATRP) and ring opening polymerization (ROP). For this purpose, a di-functional initiator with protected amino group was successfully synthetized. The ATRP of N-isopropylacrylamide yielded narrowly dispersed polymers with consistent high yields (~80%). Lower yields (~50%) were observed when narrowly dispersed random copolymers of N-isopropylacrylamide and acrylamide where synthesized. Amino-terminated poly(N-isopropylacrylamide) and poly(N-isopropylacrylamide- co-acrylamide) were successfully used as macroinitiators for ROP of N6-carbobenzoxy-L- lysine N-carboxyanhydride. The thermal behavior of the homopolymers and copolymers in aqueous solutions was studied by turbidimetry, dynamic light scattering (DLS) and proton nuclear magnetic resonance spectroscopy (1H-NMR). © 2014 by the authors; licensee MDPI, Basel, Switzerland.