Superamphiphobic Porous Structure: Design and Implementation

Abstract

Porous materials with an excellent super‐repellency exist in many applications in life and industry, and their preparation is convenient and cost effective. It would be advantageous to fabricate super‐repellent porous materials. However, because of a lack of understanding of the detailed relationship between structural features and super‐repellency, it is difficult to prepare porous materials with a superamphiphobicity. Based on a theoretical analysis and the discussion of several porous structures' repellant behaviors, the criteria for fabricating super‐repellent porous materials are proposed as: (1) the most appropriate pore size being tens of micrometers to ≈100–200 µm; (2) a larger pore height; (3) a smaller porous‐network thickness; and (4) an appropriate adequate secondary microscopic structure that favors the effective pinning of a gas–liquid–solid three‐phase contact line. According to the four criteria, an optimized superamphiphobic porous material is achieved, which is a dopamine/redox graphene‐oxide‐assembled microscale porous material, which displays a super‐repellency for droplets with a surface tension of 72.8–20 mN m−1. By using the dopamine/graphene‐assembled microscale porous material, a low gate voltage (500 V) for water impaling is acquired.

Durable Superhydrophobic Poly(vinylidene fluoride) (PVDF)-Based Nanofibrous Membranes for Reusable Air Filters

“…Detailed characterizations were performed to confirm that the filters retained hydrophobicity with a water contact angle value above 90° after ethanol treatment and also exhibit suppressed bacterial growth. However, for the filters to effectively remove PM adsorbed on the surface and also prevent saliva splash, their surface chemistry and morphology must be reconsidered to further enhance the nonwetting property of the filter. − We note that while silica nanoparticles have been applied previously in PVDF membranes to introduce additional texture and enhance the nonwetting properties, their properties do not fulfill the requirements necessary for small volume droplets to easily roll-off from the surface and their application have been strictly limited to membrane distillation. , Therefore, there remains a need for the development of a PVDF-based air filter that offers highly effective removal of PM adsorbed on the surface while simultaneously preventing saliva splash to prohibit pathogen transmission.…”