Eur. Phys. J. E (2015) 38: 2
https://doi.org/10.1140/epje/i2015-15002-y

Regular Article

On universality of scaling law describing roughness of triple line

¹ Department of Physics, Ariel University, P.O.B. 3, 40700, Ariel, Israel
² Department of Chemical Engineering and Biotechnology, Ariel University, P.O.B. 3, 40700, Ariel, Israel
³ Wolfson Applied Materials Research Center, Tel Aviv University, 69978, Ramat-Aviv, Israel

^* e-mail: Edward@ariel.ac.il

Received: 2 February 2014
Revised: 22 July 2014
Accepted: 12 January 2015
Published online: 28 January 2015

Abstract

The fine structure of the three-phase (triple) line was studied for different liquids, various topographies of micro-rough substrates and various wetting regimes. Wetting of porous and pillar-based micro-scaled polymer surfaces was investigated. The triple line was visualized with the environmental scanning electron microscope and scanning electron microscope for the “frozen” triple lines. The value of the roughness exponent $\zeta$ for water (ice)/rough polymer systems was located within 0.55-0.63. For epoxy glue/rough polymer systems somewhat lower values of the exponent, $ 0.42 < \zeta < 0.54$, were established. The obtained values of $\zeta$ were close for the Cassie and Wenzel wetting regimes, different liquids, and different substrates’ topographies. Thus, the above values of the exponent are to a great extent universal. The switch of the exponent, when the roughness size approaches to the correlation length of the defects, is also universal.