Humidity-Assisted Fabrication of Lubricant-Infiltrated, Multi-Millimeter Thick Porous Organogels for Transparent, Durable, and Self-Cleaning Films

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Fighting wintry foulants made of ice and mud requires a heavy-duty coating that prevents foulant adhesion. Lubricant-infused slippery surfaces are promising candidates; the hosting matrix must offer a large reservoir and controlled release of lubricant for prolonged practical use. The Sylgard 184 (denoted as PDMS to prevent confusion with silicone oil) matrix with regulated porosity can provide a large reservoir of lubricants; realizing a simple and cost-effective fabrication method is critical. Inspired by the breath figure method that creates periodically structured single-layered pores, we demonstrate a humidity-assisted fabrication procedure to produce multi-millimeter thick, porous PDMS films with multilayered, size-regulated, tightly packed interconnected pores. During the curing of the precursor solution containing chloroform, a complex interplay between solvent evaporation, water condensation, and chain cross-linking produces diverse morphological features. An optimized protocol produces an ∼3.5 mm thick silicone oil-infused porous film, wherein nearly the entire film is composed of spherical cellular pores with an average pore size of ∼50 μm that allows a lubricant reservoir capacity of 267% by weight. Moreover, a thin nonporous top skin controls the release of the lubricant to the surface. Additionally, the infusion of silicone oil into the substrate results in optical transparency, which can be beneficial for camera or sensor applications. The antifouling effectiveness of the silicone oil-infused PDMS film was demonstrated by a low contact angle hysteresis, an ultralow ice adhesion force, rapid sliding of clay-containing water droplets at a 10° incline angle, nonstick of ice/clay/slush mixture, standardized abrasion tests, and a two-day roadside test in harsh Albertan winter.