Effects of Substrate Surface Wettability on Ecofriendly Slippery Lubricant-Infused Porous Surfaces Inspired by Nepenthes

The slippery liquid-infused porous surfaces (SLIPS) have attracted attention in studies for various potential applications. In order to improve the liquid-repellent property and self-healing ability to mechanical forces, SLIPS with various porous structures were reported. In many studies, the porous structures were chemically treated to be hydrophobic. However, the effects of oil infusion on this substrate hydrophobicity and how it will affect the SLIPS are still not fully understood. In this study, porous surfaces inspired by Nephenthes peristome were fabricated on 316 L stainless steel by femtosecond laser ablation. Different surface treatments were applied to achieve various surface wettability properties from hydrophilic to hydrophobic. Ecofriendly almond oil was used to infuse the surfaces. The contact angle and sliding angle were examined. Surface durability were tested under aqueous exposures. Similar wetting behaviors with a contact angle of ∼80° were observed for all the SLIPS surfaces despite the huge contact angle difference for the substrate. The results suggests the binding between almond oil and substrate may overweigh the chemical hydrophobic film, leading to long-term slippery behavior with a sliding angle of <10° after stirring in water for 50 h.