The effect of side chain spacer length on the thermoresponsive behaviour of poly(methylamide acrylate)s

Abstract

We report the synthesis of three methylamide acrylate monomers with varying spacer length between the polymerizable acrylate and pendant amide functionalities; methylamide ethyl acrylate (MAmEA), methylamide propyl acrylate (MAmPA) and methylamide butyl acrylate (MAmBA). Each monomer was subsequently polymerised via redox-initiated reversible addittion-fragmentation chain transfer (RRAFT) to yield well-defined homopolymers with differing physicochemical properties. All homopolymers were found to be amorphous, and thermally degrade via a two-step decomposition process. Whilst P(MAmEA) and P(MAmPA) were found to be soluble in aqueous solution between 30–80 °C, P(MAmBA) showed a lower critical solution temperature (LCST) behaviour. Detailed aqueous solubilty studies performed on P(MAmBA) revealed that the cloud point temperature (T_cp) could be tuned based on the degree of polymerisation (DP_n), concentration and nature of the aqueous media, highlighting its potential use as a water-soluble, thermoresponsive polymer in a range of applications.