Synthesis of well-defined poly(N-isopropylacrylamide)-b-poly(L-glutamic acid) by a versatile approach and micellization

Lin Deng; Keyu Shi; Yuying Zhang; Haimei Wang; Jianguo Zeng; Xianzhi Guo; Zongjie Du; Baolong Zhang

doi:10.1016/j.jcis.2008.04.007

Synthesis of well-defined poly(N-isopropylacrylamide)-b-poly(L-glutamic acid) by a versatile approach and micellization

J Colloid Interface Sci. 2008 Jul 1;323(1):169-75. doi: 10.1016/j.jcis.2008.04.007. Epub 2008 Apr 9.

Authors

Lin Deng¹, Keyu Shi, Yuying Zhang, Haimei Wang, Jianguo Zeng, Xianzhi Guo, Zongjie Du, Baolong Zhang

Affiliation

¹ Key Laboratory of Functional Polymer Materials of Ministry Education, Department of Chemistry, Nankai University, Tianjin 300071, China.

PMID: 18448110
DOI: 10.1016/j.jcis.2008.04.007

Abstract

A novel Fmoc-protected chain transfer agent (CTA) was synthesized and applied in the reversible addition-fragmentation chain transfer (RAFT) polymerization of N-isopropylacrylamide (NIPAAm), resulting in well-defined Fmoc-protected PNIPAAm and the amino-end capped PNIPAAm by the subsequent hydrolysis. Poly(N-isopropylacrylamide)-b-poly(l-glutamic acid) (PNIPAAm-b-PLGA) with controlled molecular weight and narrow molecular weight distribution was synthesized successfully via ring-opening polymerization (ROP) of alpha-amino acid N-carboxyanhydrides (NCAs) by using PNIPAAm-NH2 as the macroinitiator. Both pH- and thermo-responsive micellization behaviors of the block copolymer PNIPAAm55-b-PLGA35 in dilute aqueous solution were investigated by means of the pyrene fluorescence, circular dichroism, 1H NMR, transmission electron microscopy and dynamic and static light scattering. Spherical PLGA-core and rod-like PNIPAAm-core micelles are formed in response to pH and temperature. The reversible transition between the PLGA-core and PNIPAAm-core micelles was observed. This work provides a versatile approach for synthesizing well-defined stimuli-responsive polypeptide-based double hydrophilic diblock copolymers (DHBCs), and is of great potential for generating useful stimuli-responsive materials in biomedical applications.