Experimental study of dynamic contact angles on rough hydrophobic surfaces

Alireza Mohammad Karim; Jonathan P Rothstein; H Pirouz Kavehpour

doi:10.1016/j.jcis.2017.11.075

Experimental study of dynamic contact angles on rough hydrophobic surfaces

J Colloid Interface Sci. 2018 Mar 1:513:658-665. doi: 10.1016/j.jcis.2017.11.075. Epub 2017 Dec 2.

Authors

Alireza Mohammad Karim¹, Jonathan P Rothstein², H Pirouz Kavehpour³

Affiliations

¹ Department of Mechanical and Aerospace Engineering, UCLA, Los Angeles, CA 90025, USA. Electronic address: amohamma@umn.edu.
² Department of Mechanical and Industrial Engineering, UMass Amherst, Amherst, MA 01003, USA.
³ Department of Mechanical and Aerospace Engineering, UCLA, Los Angeles, CA 90025, USA.

PMID: 29207348
DOI: 10.1016/j.jcis.2017.11.075

Abstract

Rough hydrophobic surfaces have many applications in industry and technology. An experimental study was done on the spreading dynamics of different concentrations of polyethylene glycol (PEG) solutions on rough Teflon plates with different roughness. The experiments were conducted using Wilhelmy plate method. The advancing dynamic contact angle was found to be weakly dependent of capillary number. However, the receding dynamic contact angle decreases with increasing capillary number. The degree of roughness on rough Teflon surface has an important role on dynamic contact angle. The dynamics of receding motion was found to follow the molecular-kinetic theory. A power law relation between the receding dynamic contact angle and the capillary number was also obtained.

Keywords: Contact line velocity; Dynamic contact angle; Molecular-kinetic theory; Rough Teflon plate; Wilhelmy plate method.