Die Benetzungseigenschaften einzelner kolloidaler Teilchen

• Applicant: Professor Dr. Hans-Jürgen Butt
• Subject Area: Experimental Condensed Matter Physics
• Term: from 1998 to 2002
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 5104200

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.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1052: Benetzung und Strukturbildung an Grenzflächen