Development of Dual-Phobic Surfaces: Superamphiphobicity in Air and Oleophobicity Underwater

In the present work, we describe a simple method to fabricate dual-phobic fluorosilane-coated polydimethylsiloxane/camphor-soot/polydimethylsiloxane (FPCP) composite surfaces. The surface morphology and silane treatment provide the needed texture on the FPCP composite surface to demonstrate superamphiphobicity in the air and oleophobicity in the underwater environment. High-resolution field emission-scanning electron microscopy (FESEM) imaging of the FPCP composite surface illustrates the top surface with an array of hollow cylindrical pillars. The dimensions of surface texture are measured, and the relationship between the wetting states of liquid and textures surface in the air as well as in an underwater environment is studied. Also, X-ray photoelectron spectroscopy (XPS) analysis demonstrates different changes of plain polydimethylsiloxane (PDMS), PDMS/camphor-soot/PDMS (PCP), and fluorosilane-coated PCP (FPCP) composite surfaces that are responsible for diverse wettability properties. We compared the experimentally observed equilibrium and dynamics contact angles of water and different oils on the FPCP composite surface in air and underwater system with those predicted by theoretical models. The results reported herein provide a new feasible method for the fabrication of dual-phobic surfaces (superamphiphobicity in air and oleophobicity underwater) with microtextures. The findings also improve the understanding of the complex relations between surface microstructure and wetting states. The fundamental understanding of dual-phobicity of FPCP composites is an important step toward the designing of optimal anti-icing surfaces for practical engineering applications. Such coatings with incorporated functionalities provide promising self-cleaning and anticorrosion applications under erosive/abrasive environment.