Issue 1, 2017

Probing the causes of thermal hysteresis using tunable Nagg micelles with linear and brush-like thermoresponsive coronas

Abstract

Self-assembled thermoresponsive polymers in aqueous solution have great potential as smart, switchable materials for use in biomedical applications. In recent years, attention has turned to the reversibility of these polymers’ thermal transitions, which has led to debate over what factors influence discrepancies in the transition temperature when heating the system compared to the temperature obtained when cooling the system, known as the thermal hysteresis. Herein, we synthesize micelles with tunable aggregation numbers (Nagg) whose cores contain poly(n-butyl acrylate-co-N,N-dimethylacrylamide) (p(nBA-co-DMA)) and four different thermoresponsive corona blocks, namely poly(N-isopropylacrylamide) (pNIPAM), poly(N,N-diethylacrylamide) (pDEAm), poly(diethylene glycol monomethyl ether methacrylate) (pDEGMA) and poly(oligo(ethylene glycol) monomethyl ether methacrylate) (pOEGMA). By studying their thermoresponsive behavior, we elucidate the effects of changing numerous important characteristics both in the thermoresponsive chain chemistry and architecture, and in the structure of their self-assemblies. Our findings demonstrate large deviations in the reversibility between the self-assemblies and the corresponding thermoresponsive homopolymers; specifically we find that micelles whose corona consist of polymers with a brush-like architecture (pDEGMA and pOEGMA) exhibit irreversible phase transitions at a critical chain density. These results lead to a deeper understanding of stimuli-responsive self-assemblies and demonstrate the potential of tunable Nagg micelles for uncovering structure–property relationships in responsive polymer systems.

Graphical abstract: Probing the causes of thermal hysteresis using tunable Nagg micelles with linear and brush-like thermoresponsive coronas

Supplementary files

Article information

Article type
Paper
Submitted
11 Jul 2016
Accepted
30 Jul 2016
First published
09 Aug 2016
This article is Open Access
Creative Commons BY license

Polym. Chem., 2017,8, 233-244

Probing the causes of thermal hysteresis using tunable Nagg micelles with linear and brush-like thermoresponsive coronas

L. D. Blackman, M. I. Gibson and R. K. O'Reilly, Polym. Chem., 2017, 8, 233 DOI: 10.1039/C6PY01191H

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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