2003/05/05 by Volker C. Weiss, Volker Weiß, Joseph O. Indekeu +2
Chemistry · Materials Science · Physics and Astronomy · #FOS: Physical sciences #Material Dynamics and Properties #Statistical Mechanics (cond-mat.stat-mech) #Surfactants and Colloidal Systems #Theoretical and Computational Physics #cond-mat.stat-mech
paper · pdf · doi:10.48550/arxiv.cond-mat/0305077
10 pages, 3 figures, contribution to the proceedings of the 15th Symposium on Thermophysical Properties, Boulder, CO (22-27 May 2003)
arxiv created 2003/05/05 · openalex publication_date 2003/05/05 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Alkanes of medium chain length show an unusual wetting behavior on (salt)\nwater, exhibiting a sequence of two changes in the wetting state. When\ndeposited on the water surface at low temperatures, the liquid alkane forms\ndiscrete droplets that are interconnected only by a molecularly thin film. On\nincrease of the temperature, there occurs a sudden jump of the film thickness\nand, at this first-order transition, a mesoscopically thick layer of liquid\nalkane is formed. Heating the system further leads to a divergence of the film\nthickness in a continuous manner. While the long-range forces between substrate\nand adsorbate are responsible for the critical transition, which occurs at the\ntemperature at which the Hamaker constant changes sign, it is primarily the\nshort-range components of the forces that bring about the first-order\ntransition. We calculate the Hamaker constant of the system and show how,\nwithin a modified Cahn theory, accurate predictions of the first-order\ntransition temperatures can be obtained for n-alkanes (pentane and hexane) on\nwater and even on brine. Furthermore, we study the variation of the contact\nangle as a function of temperature.\n