Hydrophobicity and icephobicity of micropillared silicone rubber surfaces fabricated by compression molding

Abstract

This study investigates the effects of microcylindrical pillar geometry on surface wettability and ice nucleation time. The cylindrical micropillars were designed and then fabricated on silicone rubber surfaces by micromachining to create a template, followed by direct replication using a compression molding method. This approach offers an efficient, nontoxic, and low-cost means of producing micro-nanoscale roughness on surfaces. We tested the wetting (i.e., contact angle and contact angle hysteresis) and anti-icing (i.e., ice nucleation time) properties of the patterned silicone rubber surfaces having different combinations of pillar diameter and interpillar spacing. According to our experimental results for a limited range of pillar diameters (80 and 110 μm) and center to center spacing (pitch; 125–300 μm), decreasing the diameter and increasing the space of micro-cylindrical pillars may result in the Cassie wetting until a threshold value. Beyond this pillar diameter/pitch threshold, Wenzel wetting occurred. Surfaces characterized by pillars of different diameter and pitch also increased the freezing delay by reducing the area of ice–substrate contact and the heat transfer between the water droplet and the surface. We demonstrate that the properties of superhydrophobic and anti-icing surfaces can be controlled by altering the geometry of micropillars across the surface.

Keywords

• Micromachining
• Compression molding
• Pillar array
• Hydrophobicity
• Geometry
• Ice nucleation time