Polystyrene-block-poly(ethylene oxide)-block-polystyrene: A New Synthesis Method Using Nitroxide-Mediated Polymerization from Poly(ethylene oxide) Macroinitiators and Characterization of the Architecture Formed

Abstract

The strategy developed in this report consisted of synthesizing polystyrene (PS) blocks by nitroxide-mediated controlled radical polymerization from poly(ethylene oxide) (PEO) macroinitiators. Difunctional macroinitiators were first prepared in a two-step procedure by reacting PEO (Mn ranging from 1450 to 35000 g/mol) with MONAMS, an alkoxyamine based on N-tert-butyl-N-(1-diethylphosphono-2,2-dimethylpropyl)nitroxide, called SG1. A series of polystyrene-block-poly(ethylene oxide)-block-polystyrene (PS-b-PEO-b-PS) triblock copolymers was then synthesized with various chain dimensions and PEO block mass fractions from 0.13 to 0.65. Precise insight into the prepared triblock copolymer structure in terms of molecular weight, block length, and polydispersity index was obtained using complementary characterization techniques such as 1H NMR spectroscopy and size exclusion chromatography (SEC). These data were completed by two-dimensional chromatography, a combination of liquid chromatography at the critical cond...