Method for modifying microporous membrane wettability by utilizing low pressure-forced Cassie state effect

Abstract

The invention discloses a method for modifying microporous membrane wettability by utilizing a low pressure-forced Cassie state effect. The method comprises the step of: inducing a liquid drop on a microporous membrane with the aperture of 10-100 mu m to be changed from a Wenzel state to a Cassie state at the room temperature by utilizing relative pressure of 100-300 Pa, so as to modify interfacial wettability property of the microporous membrane. Before the implementation of the above-mentioned step, preferably, surface finish is performed on the microporous membrane by adopting a surface modification technology. Under a same micropore structure, the larger the contact angle of the liquid drop on the surface of the modified microporous membrane is, the smaller the critical pressure of the forced Cassie state of the microporous membrane is. The invention provides a novel approach for designing a superhydrophobic surface. Compared with the common superhydrophobic surface, the microporous membrane has the advantages of reducing the degree of dependence on a low surface energy substance and a surface micro-nano fine structure, and decreasing the probability of failure of the surface superhydrophobic function when external pressure and the surface fine structure are damaged, therefore wide application prospect is obtained.

Description

Technical field [0001] The invention relates to a method for changing the wettability of a microporous membrane, in particular to a method for changing the wettability of a microporous membrane by using a low-pressure forced Cassie state effect. Background technique [0002] Hydrophobicity or wettability is one of the important characteristics of solid surfaces. In recent years, the research on superhydrophobic surfaces has attracted more attention. The so-called superhydrophobicity generally refers to a surface phenomenon where the contact angle of a solid surface with water is greater than 150°. People's understanding of superhydrophobic surfaces mainly comes from the self-cleaning phenomenon of various biological surfaces. Barthlott and Neinhuis observed the microstructure of the plant leaf surface and believed that this self-cleaning feature was caused by the micro-structured papillae on the rough surface and the waxy substance on the surface. Later, Feng et al. further ana...

AI Technical Summary

Problems solved by technology

However, from a thermodynamic analysis, the Cassie state droplet on the rough surface of most materials is a metastable state, and the Wenzel state is a stable state. Once the external pressure overcomes the energy barrier from the Cassie state to the Wenzel state transition, the gas-solid interface disappears and becomes liquid-solid interface, thereby causing the failure of surface superhydrophobicity

In addition, the micro-nano fine structure of the superhydrophobic surface is also easily damaged by external friction and other factors, resulting in the failure of the superhydrophobic effect.

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