Effect of Molecular Structure on Wetting Behavior at the Air-Liquid Interface of Water + Alcohol Mixtures
Journal
Journal of Physical Chemistry B
Journal Volume
108
Journal Issue
28
Pages
9955-9961
Date Issued
2004
Date
2004
Author(s)
Abstract
In this study, the wetting behavior of binary water + alcohol mixtures was carefully investigated by using eight different short-chain alcohols. These binary mixtures exhibit liquid-liquid equilibrium over the experimental temperature range 10-40°C. The wetting behavior of the upper liquid (alcohol-rich) phase at the surface of the lower liquid (aqueous) phase can be determined according to the wetting coefficient resulting from the interfacial tension measurements. Molecular structure of alcohols plays an essential role in the wetting behavior. The purpose of this study is threefold. (1) The effect of the hydrocarbon chain length of alcohols was examined by employing water + 1-butanol (C4E0), water + 1-pentanol (C5E 0), and water + 1-hexanol (C6E0) three systems, where CiEj is the abbreviation of a nonionic polyoxyethylene alcohol CiH2i+1(OCH2-CH 2)jOH. The shorter chain alcohol has a stronger tendency to wet the surface of the aqueous phase. (2) The effect of number of oxyethylene groups of alcohols was investigated by using three mixtures, water + C6E0, water + C6E1, and water + C6E2. An interfacial phase transition from partial wetting to nonwetting was observed for water + C6Ej mixtures as the number of oxyethylene groups j increases from 1 to 2. (3) The effect of isomeric structures of alcohols on wetting behavior was investigated by studying three mixtures, water + 1-pentanol, water + 2-pentanol (2-C 5E0), and water + tert-pentanol (t-C5E 0). An interfacial phase transition from partial wetting to complete wetting occurs while the molecular structure of alcohols evolves from linear (C5E0) to near spherical (t-C5E0) shape.
Other Subjects
Adsorption; Alcohols; Binary mixtures; Ellipsometry; Gas chromatography; Interfaces (materials); Osmosis; Phase diagrams; Phase transitions; Surface tension; Ternary systems; Thermodynamics; Thermostats; Wetting; Amphiphilicity; Aqueous phase; Droplets; Nonwetting; Molecular structure
Type
journal article
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