Ettelaie, R orcid.org/0000-0002-6970-4650, Dickinson, E and Pugnaloni, L (2014) First-order phase transition during displacement of amphiphilic biomacromolecules from interfaces by surfactant molecules. Journal of Physics: Condensed Matter, 26 (46). 464109. ISSN 0953-8984
Abstract
The adsorption of surfactants onto a hydrophobic interface, already laden with a fixed number of amphiphilic macromolecules, is studied using the self consistent field calculation method of Scheutjens and Fleer. For biopolymers having unfavourable interactions with the surfactant molecules, the adsorption isotherms show an abrupt jump at a certain value of surfactant bulk concentration. Alternatively, the same behaviour is exhibited when the number of amphiphilic chains on the interface is decreased. We show that this sudden jump is associated with a first-order phase transition, by calculating the free energy values for the stable and the metastable states at both sides of the transition point. We also observe that the transition can occur for two approaching surfaces, from a high surfactant coverage phase to a low surfactant coverage one, at sufficiently close separation distances. The consequence of this finding for the steric colloidal interactions, induced by the overlap of two biopolymer + surfactant films, is explored. In particular, a significantly different interaction, in terms of its magnitude and range, is predicted for these two phases. We also consider the relevance of the current study to problems involving the competitive displacement of proteins by surfactants in food colloid systems.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2014 IOP Publishing Ltd. This is an author-created, un-copyedited version of an article accepted for publication in Journal of Physics: Condensed Matter. The publisher is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. The Version of Record is available online at https://doi.org/10.1088/0953-8984/26/46/464109. |
Keywords: | mixed surfactant + biopolymer films; first-order phase transition; colloidal steric interactions |
Dates: |
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Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Food Science and Nutrition (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 03 Jul 2015 11:11 |
Last Modified: | 03 Feb 2018 02:29 |
Published Version: | https://doi.org/10.1088/0953-8984/26/46/464109 |
Status: | Published |
Publisher: | IOP Publishing |
Identification Number: | 10.1088/0953-8984/26/46/464109 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:85085 |