Synthesis of Well-Defined Alternating Copolymer Composed of Ethylmaleimide and Hydroxy-Functionalized Vinyl Ether by RAFT Polymerization and Their Thermoresponsive Properties.

Jin Motoyanagi,Masahiko Minoda,Ayaha Oguri

doi:10.3390/polym12102255

Abstract

Here we report the controlled synthesis of alternating copolymers by reversible addition-fragmentation chain transfer (RAFT) polymerization of hydroxy-functionalized vinyl ether (DEGV) and ethylmaleimide (EtMI) using dithiocarbonate derivative (CPDB) as the RAFT reagent. The resulting alternating copolymer poly[ethylmaleimide-alt-(diethylene glycol mono vinyl ether)] (poly(MalMI-alt-DEGV)) had a relatively narrow molecular weight distribution (Mw/Mn < 1.4). These polymers are fully soluble in cold water (5 °C) and an aqueous solution of poly(MalMI-alt-DEGV) became turbid upon heating (using an incident wavelength of 600 nm and 1.0 mg mL−1 (0.1 wt %) polymer concentration), indicating phase separation above the cloud point temperature (Tcp). The Tcp of the polymer solution ranged from 15–35 °C, depending on the molecular weight and molecular weight distribution of the polymer.

Highlights

Recent advances in controlled polymerization techniques have enabled the preparation of various well-defined polymers with predetermined molecular weights and low polydispersity
Most hydroxy-containing copolymers obtained by copolymerization with hydrophobic units are lower critical solution temperature (LCST)-type thermoresponsive materials which are soluble in water, but become insoluble above a certain temperature upon heating
DEGV and EtMI were copolymerized using AIBN with or without CPDB as the reversible addition-fragmentation chain transfer (RAFT) agent

Summary

Introduction

Recent advances in controlled polymerization techniques have enabled the preparation of various well-defined polymers with predetermined molecular weights and low polydispersity. Most hydroxy-containing copolymers obtained by copolymerization with hydrophobic units are lower critical solution temperature (LCST)-type thermoresponsive materials which are soluble in water, but become insoluble above a certain temperature (cloud point temperature; Tcp ) upon heating. Such thermoresponsive polymers are of great interest for nanotechnology and biomedical applications [17,18,19,20]. Controlling the Polymers 2020, 12, 2255; doi:10.3390/polym12102255 www.mdpi.com/journal/polymers

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Conclusion