文献类型：期刊文献

英文题名：Self-assembly behavior of pH- and thermosensitive amphipbilic triblock copolymers in solution: Experimental studies and self-consistent field theory simulations

作者：Cai, Chunhua[1]; Zhang, Liangshun[1]; Lin, Jiaping[1]; Wang, Liquan[1]

机构：[1] Key Laboratory for Ultrafine Materials, East China University of Science and Technology, Ministry of Education, Shanghai 200237, China

年份：2008

卷号：112

期号：40

起止页码：12666

外文期刊名：Journal of Physical Chemistry B

收录：EI(收录号：20084411670995)

语种：英文

外文关键词：Block copolymers - Amino acids - Molecular orbitals - Dynamic light scattering - Mean field theory - pH - Self assembly - Dichroism - Scanning electron microscopy - Micelles - Solutions - High resolution transmission electron microscopy

摘要：We investigated, both experimentally and theoretically, the self-assembly behaviors of pH- and thermosensitive poly(L-glutamic acid)-b-poly(propylene oxide)-b-poly(L-glutamic acid) (PLGA-b-PPO-WLGA) triblock copolymers in aqueous solution by means of transmission electron microscopy (TEM), scanning electron microscopy (SEM), dynamic light scattering (DLS), circular dichroism (CD), and self-consistent field theory (SCFT) simulations. Vesicles were observed when the hydrophilic PLGA block length is shorter or the pH value of solution is lower. The vesicles were found to transform to spherical micelles when the PLGA block length increases or its conformation changes from helix to coil with increasing the pH value. In addition, increasing temperature gives rise to a decrease in the size of aggregates, which is related to the dehydration of the PPO segments at higher temperatures. The SCFT simulation results show that the vesicles transform to the spherical micelles with increasing the fraction or statistical length of A block in model ABA triblock copolymer, which corresponds to the increase in the PLGA length or its conformation change from helix to coil in experiments, respectively. The SCFT calculations also provide chain distribution information in the aggregates. On the basis of both experimental and SCFT results, the mechanism of the structure change of the PLGA-b-PPO-b-PLGA aggregates was proposed. ? 2008 American Chemical Society.