Bioinspired Scalable Lubricated Bicontinuous Porous Composites with Self-Recoverability and Exceptional Outdoor Durability

Abstract

Lubricant-impregnated surfaces (LIS) are promising as efficient liquid-repellent surfaces, which comprise a surface lubricant layer stabilized by base solid structures. However, the lubricant layer is susceptible to depletion upon exposure to degrading stimuli, leading to the loss of functionality. Lubricant depletion becomes even more pronounced in exposed outdoor conditions, restricting LIS to short-term lab-scale applications. Thus, the development of scalable and long-term stable LIS suitable for practical outdoor applications remains challenging. In this work, we designed "Lubricated Bicontinuous porous Composites" (LuBiCs) by infusing a silicone oil lubricant into a bicontinuous porous composite matrix of tetrapod-shaped zinc oxide microfillers and poly(dimethylsiloxane). LuBiCs are prepared in the meter scale by a facile drop-casting inspired wet process. The bicontinuous porous feature of the LuBiCs enables capillarity-driven spontaneous lubricant transport throughout the surface without any external driving force. Consequently, the LuBiCs can regain liquid-repellent function upon lubricant depletion via capillary replenishment from a small, connected lubricant reservoir, making them tolerant to lubricant-degrading stimuli (e.g., rain shower, surface wiping, and shearing). As a proof-ofconcept, we show that the large-scale "LuBiC roof" retains slippery behavior even after more than 9 months of outdoor exposure.

Directional Manipulation of Drops and Solids on a Magneto-Responsive Slippery Surface

“…In general, a lubricating oil (nonmagnetic) is infused into the porous matrix of a solid substrate to fabricate slippery surfaces. 49 Herein, in our study, to impart magnetic attributes to the substrate, we infuse an oil-based ferrofluid into the porous structure of a Glaco-coated glass slide to prepare the MRSS, as shown in Figure 1a. Incorporation of the ferrofluid into the porous structures impregnates the substrate with magnetic attributes and remains held by capillary forces, which in turn serves two purposes: (a) it results in a magnetoresponsive slippery surface and (b) a moving magnetic field can replenish the depletion zones (created after long usage), which is challenging in the case of nonmagnetic lubricating oil.…”

“…In general, a lubricating oil (nonmagnetic) is infused into the porous matrix of a solid substrate to fabricate slippery surfaces . Herein, in our study, to impart magnetic attributes to the substrate, we infuse an oil-based ferrofluid into the porous structure of a Glaco-coated glass slide to prepare the MRSS, as shown in Figure a.…”