Synthesis, self-assembly, and thermosensitivity of amphiphilic POEGMA-PDMS-POEGMA triblock copolymers

Abstract

In this article, the synthesis and self-assembly of a novel well-defined biocompatible amphiphilic POEGMA-PDMS-POEGMA triblock copolymer were studied. The copolymer was synthesized by atom transfer radical polymerization of oligo(ethylene glycol) methyl ether methacrylate (OEGMA) using α,ω-dibromo polydimethylsiloxane macroinitiator (Br-PDMS-Br). Br-PDMS-Br was synthesized through the esterification of α,ω- hydroxypropyl polydimethylsiloxane and 2-bromoisobutyryl bromide. The structures of the copolymers were confirmed by proton nuclear magnetic resonance spectroscopy, and gel permeation chromatography. The copolymers showed reversible aggregation in response to temperature cycles with a lower critical solution temperature (LCST) between 61 and 66 °C, as determined by ultraviolet-visible spectrophotometry and dynamic light scattering. The LCST values increased in proportion to the length of the hydrophilic block and were lower than that of the POEGMA homopolymer. The self-assembly behavior of the copolymers in aqueous solution was investigated by fluorescence spectroscopy and transmission electron microscopy. The critical micelle concentration value (1.08-0.26 10-6 mol L-1) decreased as the length of the POEGMA chain increased. The POEGMA-PDMS-POEGMA copolymers can easily self-assemble into spherical micelles in aqueous solution. Such biocompatible block copolymers may be attractive candidates as ''smart'' thermo-responsive drug delivery systems. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014, 52, 2684-2691 A well-defined biocompatible amphiphilic POEGMA-PDMS-POEGMA triblock copolymer was synthesized by atom transfer radical polymerization using α,ω-dibromo polydimethylsiloxane as a macroinitiator. The copolymers had good thermosensitivity, with reversible and sharp phase separation. The copolymers had low critical micelle concentration values and easily self-assembled into spherical micelles in aqueous solution. © 2014 Wiley Periodicals, Inc.