EFFECTS OF MOLECULAR WEIGHT ON THERMAL RESPONSIVE PROPERTY OF PEGYLATED POLY-L-GLUTAMATES

作     者：Shusheng Zhang Chongyi Chen 李志波 

作者机构：Laboratory of Polymer Physics and Chemistry Institute of Chemistry Chinese Academy of Sciences 

出 版 物：《Chinese Journal of Polymer Science》 (高分子科学（英文版）)

年 卷 期：2013年第31卷第2期

页      面：201-201,202-210页

核心收录：

学科分类：081704[工学-应用化学] 07[理学] 0817[工学-化学工程与技术] 08[工学] 070305[理学-高分子化学与物理] 080501[工学-材料物理与化学] 0805[工学-材料科学与工程（可授工学、理学学位）] 0703[理学-化学] 

基　　金：financially supported by the National Natural Science Foundation of China (Nos. 20974112 and 51225306) 

主　　题：N-carboxyanhydride (NCA) Ring opening polymerization Polypeptide Helicity Thermal responsive. 

摘      要：We investigated the ring opening polymerization （ROP） of di- and tri-ethylene glycol monomethyl ether functionalized L-glutamate N-carboxyanhydrides （NCAs） using hexamethyldisilazane （HMDS） as primary initiator and 1,5,7-triazabicyclo-[4.4.0]dec-5-ene （TBD） as co-initiator. The binary initiator system afforded a living ROP for these pegylated NCAs, and a series of homopolypeptides with controlled molecular weight （MW） and low polydispersity were obtained. We then systematically studied the helical content and clouding point （CP） dependence on polypeptide MW using circular dichroism （CD） spectroscopy and turbidity measurements, respectively. We found that the helical content of both homopolypeptides increased with MW, but the triethylene glycol functionalized poly-L-glutamate （poly-L-EG3Glu） intended to form more stable or-helical structure than diethylene glycol functionalized counterpart （poly-L-EG2Glu） at similar MW. Accordingly, the CP of poly-L-EG2Glu with known end group has strong dependence on its helical content, which is essentially determined by MW. Our results suggested that the thermal responsive properties of these unique pegylated poly- L-glutamates not only rely on their chemical structure but also on their secondary structures, wh^ch is different from conventional thermal responsive polymers.