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Synergy, competition, and the “hanging” polymer layer: Interactions between a neutral amphiphilic ‘tardigrade’ comb co-polymer with an anionic surfactant at the air-water interface

Research output: Contribution to journalArticle

Original languageEnglish
Pages (from-to)181-194
Number of pages14
JournalJournal of Colloid and Interface Science
Volume561
Early online date30 Nov 2019
DOIs
DateAccepted/In press - 5 Nov 2019
DateE-pub ahead of print - 30 Nov 2019
DatePublished (current) - 1 Mar 2020

Abstract

Understanding the structure of polymer/surfactant mixtures at the air-water interface is of fundamental importance and also of relevance to a variety of practical applications. Here, the complexation between a neutral ’tardigrade’ comb co-polymer (consisting of a hydrophilic polyethylene glycol backbone with hydrophobic polyvinyl acetate grafts, PEG-g-PVAc) with an anionic surfactant (sodium dodecyl sulfate, SDS) at the air-water interface has been studied. Contrast-matched neutron reflectivity (NR) complemented by surface tension measurements allowed elucidation of the interfacial composition and structure of these mixed systems, as well as providing physical insights into the polymer/surfactant interactions at the air-water interface. For both polymer concentrations studied, below and above its critical aggregation concentration, cac, (0.2 cac and 2 cac, corresponding to 0.0002 wt% or 0.013 mM and 0.002 wt% or 0.13 mM respectively), we observed a synergistic cooperative behaviour at low surfactant concentrations with a 1–2 nm mixed interfacial layer; a competitive adsorption behaviour at higher surfactant concentrations was observed where the polymer was depleted from the air-water interface, with an overall interfacial layer thickness ~1.6 nm independent of the polymer concentration. The weakly associated polymer layer “hanging” proximally to the interface, however, played a role in enhancing foam stability, thus was relevant to the detergency efficacy in such polymer/surfactant mixtures in industrial formulations.

    Research areas

  • Air-water interface, Comb co-polymer, Competition, Foaming, Neutron reflectivity, Polymer/surfactant interactions, Synergy

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  • Full-text PDF (author’s accepted manuscript)

    Rights statement: This is the author accepted manuscript (AAM). The final published version (version of record) is available online via Elsevier at https://www.sciencedirect.com/science/article/pii/S0021979719313360#! . Please refer to any applicable terms of use of the publisher.

    Accepted author manuscript, 2.55 MB, PDF document

    Embargo ends: 30/11/21

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    Licence: CC BY-NC-ND

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