Modelling the interfacial behaviour of dilute light-switching surfactant solutions

JOURNAL OF COLLOID AND INTERFACE SCIENCE

卷:445

Article

Herdes, Carmelo¹  Santiso, Erik E.²  James, Craig³  Eastoe, Julian⁴  Mueller, Erich A.¹ 

[1] Univ London Imperial Coll Sci Technol & Med, Dept Chem Engn, London SW7 2AZ, England

[2] N Carolina State Univ, Dept Chem & Biomol Engn, Raleigh, NC 27695 USA

[3] Hirosaki Univ, Grad Sch Sci & Technol, Dept Frontier Mat Chem, Hirosaki, Aomori 0368561, Japan

[4] Univ Bristol, Sch Chem, Bristol BS8 1TS, Avon, England

关键词: Molecular dynamics;    Surface tension;    Molecular simulation;    Coarse graining;    SAFT;    Amphiphiles;    Complex fluids;    CMC;   

DOI  :  10.1016/j.jcis.2014.12.040

来源: Elsevier

【 摘 要 】

The direct molecular modelling of an aqueous surfactant system at concentrations below the critical micelle concentration (pre-cmc) conditions is unviable in terms of the presently available computational power. Here, we present an alternative that combines experimental information with tractable simulations to interrogate the surface tension changes with composition and the structural behaviour of surfactants at the water air interface. The methodology is based on the expression of the surface tension as a function of the surfactant surface excess, both in the experiments and in the simulations, allowing direct comparisons to be made. As a proof-of-concept a coarse-grained model of a light switching non-ionic surfactant bearing a photosensitive azobenzene group is considered at the air water interface at 298 K. Coarse-grained molecular dynamic simulations are detailed based on the use of the SAFT force field with parameters tuned specifically for this purpose. An excellent agreement is obtained between the simulation predictions and experimental observations; furthermore, the molecular model allows the rationalization of the macroscopic behaviour in terms of the different conformations of the cis and trans surfactants at the surface. (C) 2014 Elsevier Inc. All rights reserved.

【 授权许可】

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