Issue 9, 2017

Characterisation of hydration and nanophase separation during the temperature response in hydrophobic/hydrophilic elastin-like polypeptide (ELP) diblock copolymers

Abstract

To understand the complex nanoscale dehydration process during the lower critical solution temperature (LCST) based inverse phase transition of a class of thermoresponsive biopolymers, diblock elastin-like polypeptides (ELPs) were investigated by spin probing continuous wave electron paramagnetic resonance (CW EPR) spectroscopy. The diblock copolymers composed of a hydrophobic block and a hydrophilic block showed different mechanisms of a temperature-driven phase transition. While the phase transition temperature is a function of the hydrophobic mass fraction of the diblock ELPs, the hydrophilic block length determines the molecular structure of the polymer aggregates formed above the transition temperature. When the weight ratio of hydrophilic block length to hydrophobic block length is greater than or equal to 0.3, the polymer aggregates consist of a hydrophobic core and a hydrophilic corona. The interface of these two regions become permeable at temperatures above the transition temperature. In case of smaller ratios, the aggregating hydrophobic parts of the polymer enclose the hydrated hydrophilic blocks, that are too small to form a hydrophilic corona, leading to bigger and less dense aggregates of higher polarity.

Graphical abstract: Characterisation of hydration and nanophase separation during the temperature response in hydrophobic/hydrophilic elastin-like polypeptide (ELP) diblock copolymers

Supplementary files

Article information

Article type
Paper
Submitted
27 Oct 2016
Accepted
31 Jan 2017
First published
31 Jan 2017
This article is Open Access
Creative Commons BY license

Soft Matter, 2017,13, 1816-1822

Characterisation of hydration and nanophase separation during the temperature response in hydrophobic/hydrophilic elastin-like polypeptide (ELP) diblock copolymers

K. Widder, S. R. MacEwan, E. Garanger, V. Núñez, S. Lecommandoux, A. Chilkoti and D. Hinderberger, Soft Matter, 2017, 13, 1816 DOI: 10.1039/C6SM02427K

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