The expansion of the three-phase contact between a small air bubble and a flat solid surface is studied experimentally by means of a CCD high-speed video technique. Quartz surfaces are rendered hydrophobic by the Langmuir-Blodgett technique and by methylation. Our molecular-kinetic model for TPC expansion, which accounts for the effect of solid-gas-liquid three-phase contact line tension, is used successfully to describe the experimental dewetting data. The line tension is a relevant parameter which controls the dewetting and coalescence processes with a small wetting perimeter. The order of the line tension in our experiments is 1 mu J m(-1), which is consistent with the data obtained by other measuring techniques for similar hydrophobic surfaces. (C) 1998 Elsevier Science B.V. All rights reserved. [References: 20]
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