Alkane/alcohol mixed monolayers at the solid/liquid interface

Messe, L. and Perdigon, A. and Clarke, S. M. and Inaba, A. and Arnold, T. (2005) Alkane/alcohol mixed monolayers at the solid/liquid interface. Langmuir, 21 (11). pp. 5085-5093. DOI 10.1021/la0501280

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Abstract

In this work, we present the behavior of solid monolayers of binary mixtures of alkanes and alcohols adsorbed on the surface of graphite from their liquid mixtures. We demonstrate that solid monolayers form for all the combinations investigated here. Differential scanning calorimetry (DSC) is used to identify the surface phase behavior of these mixtures, and elastic neutron incoherent scattering has been used to determine the composition of the mixed monolayers inferred by the calorimetry. The mixing behavior of the alcohol/alkane monolayer mixtures is compared quantitatively with alkane/alkane and alcohol/alcohol mixtures using a regular solution approach to model the incomplete mixing in the solid monolayer with preferential adsorption determining the surface composition. This analysis indicates the preferential adsorption of alcohols over alkanes of comparable alkyl chain length and even preferential adsorption of shorter alcohols over longer alkanes, which contrasts strongly with mixtures of alkane/alkane and alcohol/alcohol of different alkyl chain lengths where the longer homologue is always found to preferentially adsorb over the shorter. The alcohol/alkane mixtures are all found to phase separate to a significant extent in the adsorbed layer mixtures even when molecules are of a similar size. Again, this contrasts strongly with alkane/alkane and alcohol/alcohol mixtures where, although phase separation is found for molecules of significantly different size, good mixing is found for similar size species.

Item Type: Article
Uncontrolled Keywords: 2005 AREP 2005 P IA48 BPI
Subjects: 99 - Other
Divisions: 99 - Other
Journal or Publication Title: Langmuir
Volume: 21
Page Range: pp. 5085-5093
Identification Number: 10.1021/la0501280
Depositing User: Sarah Humbert
Date Deposited: 13 Nov 2010 11:12
Last Modified: 23 Jul 2013 09:59
URI: http://eprints.esc.cam.ac.uk/id/eprint/1749

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