Y-shaped block copolymers of poly(ethylene glycol) and poly(N-isopropylacrylamide) synthesized by ATRP

作     者：Xin De Tang Xiao Chao Liang Nian Feng Han 

作者机构：Institute of New Materials Shandong Jiaotong University Ji'nan 250023 China College of Chemistry & Molecular Engineering Peking University Beijing 100871 China 

出 版 物：《Chinese Chemical Letters》 (中国化学快报（英文版）)

年 卷 期：2009年第20卷第11期

页      面：1353-1356页

核心收录：

学科分类：07[理学] 070304[理学-物理化学(含∶化学物理)] 070305[理学-高分子化学与物理] 0703[理学-化学] 

基　　金：support from the National Natural Science Foundation of China(No. 20134020) the Visiting Scholar Project of Shandong Province of China(No.20081001) the Science Research Fund of Shandong Jiaotong University of China(No.Z200802) 

主　　题：Y-shaped Block copolymer Poly（ethylene glycol） Poly（N-isopropylacrylamide） Atom transfer radical polymerization （ATRP） 

摘      要：Novel Y-shaped block copolymers of poly（ethylene glycol） and poly（N-isopropylacrylamide）, PEG-b-（PNIPAM）2, were successfully synthesized through atom transfer radical polymerization （ATRP）. A difunctional macroinitiator was prepared by esterification of 2,2-dichloroacetyl chloride with poly（ethylene glycol） monomethyl ether （PEG）. The copolymers were obtained via the ATRP ofN-isopropylacrylamide （NIPAM） at 30℃ with CuCl/Me6TREN as a catalyst system and DMF/H2O （v/v = 3：1） mixture as solvent. The resulting copolymers were characterized by gel permeation chromatography （GPC） and ^1H NMR. These block copolymers show controllable molecular weights and narrow molecular weight distributions （PDI 〈 1.15）. Their phase transition temperatures and the corresponding enthalpy changes in aqueous solution were measured by differential scanning calorimetry （DSC）. As a result, the phase transition temperature of PEG45-b-（PNIPAM55）2 is higher than that of PNIPAM, however, the corresponding enthalpy change is much lower, indicating the significant influence of the macromolecular composition and architecture on the phase transition.