Wetting dynamics on lyophilic solid surfaces patterned by lyophobic islands

TL;DR

This paper develops a theoretical model for wetting dynamics on structured surfaces with lyophobic islands on lyophilic backgrounds, validated by experiments with zinc droplets on patterned iron surfaces, showing complete wetting due to surface patterning.

Contribution

It introduces a delta-comb periodic potential model incorporating line tension and friction, revealing how lyophobic patterns induce complete wetting on lyophilic surfaces.

Findings

Negative effective line tension influences spreading dynamics.

Lyophobic patterns lead to complete wetting without a contact angle.

The model accurately describes experimental spreading behavior.

Abstract

A theory for wetting of structured solid surfaces is developed, based on the delta-comb periodic potential. It possesses two matching parameters: the effective line tension and the friction coefficient on the three-phase contact line at the surface. The theory is validated on the dynamics of spreading of liquid zinc droplets on morphologically patterned zinkophilic iron surface by means of square patterns of zinkophobic aluminum oxide. It is found that the effective line tension is negative and it has essential contribution to the dynamics of spreading. Thus, the theoretical analysis shows that the presence of lyophobic patterns situated on lyophilic surface makes the latter completely wettable, i.e. no equilibrium contact angle on such surface exists making the droplet spread completely in form of thin liquid layer on the patterned surface.