Superhydrophobic nanofibrous polytetrafluoroethylene and composite membranes with tunable adhesion for micro-droplet manipulation, self-cleaning and oil/water separation

Abstract

Membrane technology has been proven to be highly valuable in extensive applications, such as separation and purification, surface engineering, packaging, and electronics. Controllable surface wetting behavior is pivotal in determining the practical applications of membranes in various scenarios. In this study, a superhydrophobic nanofibrous membrane with diverse adhesion was prepared by a novel in-situ fibrillation of polytetrafluoroethylene (PTFE). The fibrous structures can be facilely manipulated by the processing temperatures, and a hierarchical structure of micro-/nano-scale PTFE fibrils simultaneously achieves superhydrophobicity with high adhesion. In contrast, a superhydrophobic surface with extremely low adhesion was fabricated by in-situ introducing SiO2 microspheres into membrane. Therefore, the distinct adhesion of the membranes enables multifunctional applications that require different liquid wettability, such as the manipulation of tiny droplets, self-cleaning, and anti-icing properties. Furtherly, the nanofibrous membranes demonstrated outstanding oil/water separation performance with great efficiency over 99.5% and flux as high as 5303 L·m−2·h−1. The fabricated nanofibrous PTFE membrane, exhibiting either a “petal effect” or “lotus effect”, along with their flexible fabrication methodology, offer a promising approach to meet the demand for chemical, environment, and biomedicine area.