Friction behavior of silicone rubber hemisphere under non-uniform wetting states: With water droplets in air or air bubbles in water

The friction behavior of rubber is sensitive to real contact formation, especially on flat floors, and it can be determined by the wetting distribution (uniform or non-uniform). Here, we investigated the friction behavior and contact condition between a rubber hemisphere and a glass plate under non-uniform wetting conditions with water droplets in air and air bubbles in water. The experimental results indicated that the friction coefficient and real contact area for non-uniform wetting conditions were higher than for uniform wetting conditions without water droplets and air bubbles. Considering non-uniform wetting, a dewetting theory was developed that explains promotion of real contact formation.