Jump to main content
Jump to site search

Issue 1, 2006
Previous Article Next Article

Freezing transitions in mixed surfactant/alkane monolayers at the air–solution interface

Author affiliations

Abstract

Mixed monolayers at the air–water interface of the cationic surfactant, hexadecyltrimethylammonium bromide (CTAB), with alkanes show a first-order freezing transition as a function of temperature. Sum-frequency spectra and ellipsometric measurements are consistent with a structure in which the high-temperature phase is liquid-like and the low-temperature phase has all-trans, upright chains. There are strong structural similarities between the low-temperature phase in the mixed monolayers and frozen monolayers at the alkane–air and alkane–CTAB solution interfaces. The difference between the surface freezing point Ts and the freezing point of the bulk alkane Tb ranges from 1 °C for alkane chain length m = 17, to 28 °C for m = 11. Surface freezing is more favourable in mixed monolayers at the air–water interface than at the bulk alkanewater interface for the same surfactant concentration. Long-chain alkanes do not wet water, but it is postulated that if they did, they would also show surface freezing analogously to alkanes on silica. The surfactant plays the dual role of enhancing wetting and surface freezing of the alkane on water.

Graphical abstract: Freezing transitions in mixed surfactant/alkane monolayers at the air–solution interface

Back to tab navigation

Publication details

The article was received on 15 Aug 2005, accepted on 26 Oct 2005 and first published on 14 Nov 2005


Article type: Paper
DOI: 10.1039/B511561B
Citation: Soft Matter, 2006,2, 66-76
  •   Request permissions

    Freezing transitions in mixed surfactant/alkane monolayers at the air–solution interface

    K. M. Wilkinson, L. Qunfang and C. D. Bain, Soft Matter, 2006, 2, 66
    DOI: 10.1039/B511561B

Search articles by author

Spotlight

Advertisements