Die Benetzungseigenschaften einzelner kolloidaler Teilchen

点击翻译按钮获取中文摘要

For a better understanding of wetting phenomena in the micrometer regime we developed a technique to measure the contact angle of individual spherical particles ( 2-20 µm). The developed set-up is closely related to the design of atomic force microscopes. Advancing (ja) and receding contact angles (jt) can be determined with an accuracy of 1-2°. Two preliminary results are:1. Contact angles determined on fine particles differ in a systematic way from contact angles measured on similarly prepared planar surfaces.We plan to find out weather this discrepancy can be explained by a line tension and how it is related to surface forces.2. The hysteresis ja-jt measured with particles is usually significantly smaller than the hysteresis determined on planar surfaces.We intend to clarify the role of advancing, receding and equilibrium contact angle with respect to the use to fine particles.