EFFECT OF MICRO-STRUCTURAL GEOMETRY ON LUBRICANT INFILTRATION AND PROPERTY OF SLIPPERY LIQUID-INFUSED POROUS SURFACES

Abstract

Liquid-infused porous surfaces inspired by Nepenthes pitcher plant were fabricated on polyurethane. Five different micro-structures, including pillar (PIL), Sharklet[Formula: see text] (SHK), continuous discrete ridge (DIR), hole (HOL) and networking (NET), were fabricated by soft lithography. Effects of micro-structural geometry on lubricant infiltration capability were investigated by infiltration the micro-structures with two lubricants of different viscosity, Krytox-103 ([Formula: see text]: 0.131 [Formula: see text]) and Krytox-105 ([Formula: see text]). The lubricant infiltration and retention capability were determined using a confocal laser scanning micro-scopy, and properties of the infused surfaces were evaluated by measuring the speed of water droplet motion at various tilting angles. The results revealed that, for the 80[Formula: see text][Formula: see text]m-high micro-structures, infiltration with a less viscous Krytox-103 resulted in more complete infiltration and retention, particularly for the PIL micro-structure. The infused surface exhibited a slippery behavior signified by low sliding angle and good anti-adhesion against chlorophyll fluid and milk yogurt. The lubricant retention capability was significantly reduced for the 7[Formula: see text][Formula: see text]m-high micro-structures due to lower aspect ratio and low capillary force. In this case, the PIL infused with a more viscous Krytox-105 provided a slippery surface.