Alternative Route to Nanoscale Aggregates with a pH-Responsive Random Copolymer

Jonathan C. Pegg, Adam Czajka, Christopher Hill, Craig James, Jocelyn Peach, Sarah E. Rogers, Julian Eastoe*

*Corresponding author for this work

Research output: Contribution to journalArticle (Academic Journal)

5 Citations (Scopus)
177 Downloads (Pure)

Abstract

A random copolymer, poly(methyl methacrylate-co-2-dimethylaminoethyl methacrylate) (poly(MMA-co-DMAEMA)) is shown to form nanoscale aggregates (NAs) (∼20 nm) at copolymer concentrations ≥10% w/w, directly from the preformed surfactant-stabilized latex (∼120 nm) in aqueous solution. The copolymer is prepared by conventional emulsion polymerization. Introducing a small mole fraction of DMAEMA (∼10%) allows the copolymer hydrophilicity to be adjusted by the pH and external temperature, generating NAs with tuneable sizes and a defined weight-average aggregation number, as observed by dynamic light scattering (DLS) and small-angle neutron scattering (SANS). These NAs are different from the so-called mesoglobular systems and are insensitive to temperature at fixed pH. The relatively broad chemical composition distribution of the copolymer and lumpy (or blocky but not diblock) incorporation of DMAEMA mean that the NAs cannot be simply thought of as conventional polymer micelles. In the acidic pH regime, the amphiphilic copolymer exhibits a defined critical assembly concentration (CAC) and a minimum air-water surface tension of 45.2 mN m-1. This copolymer represents a convenient route to self-assembled NAs, which form directly in aqueous dispersions after pH and temperature triggers, rather than the typically applied (and time-consuming) water-induced micellization approach for common polymer micelles.

Original languageEnglish
Pages (from-to)2628-2638
Number of pages11
JournalLangmuir
Volume33
Issue number10
Early online date20 Feb 2017
DOIs
Publication statusPublished - 14 Mar 2017

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    Pegg, J. C., Czajka, A., Hill, C., James, C., Peach, J., Rogers, S. E., & Eastoe, J. (2017). Alternative Route to Nanoscale Aggregates with a pH-Responsive Random Copolymer. Langmuir, 33(10), 2628-2638. https://doi.org/10.1021/acs.langmuir.6b04559