Extraordinary Superhydrophobic Polycaprolactone-Based Composite Membrane with an Alternated Micro–Nano Hierarchical Structure as an Eco-friendly Oil/Water Separator
Nana He, Lili Li, Jiaqi Chen, Junhao Zhang, Ce Liang
Abstract
Extraordinary superhydrophobic polycaprolactone (PCL) composite membranes with an alternated hierarchical micro–nano structure were designed by addition of SiO2 aerogel. The highest water contact angle (WCA) of 166.8 ± 1.5° was obtained when SiO2 aerogel content was 0.5% (PCL/SiO2-a0.5) in the PCL composite membrane, which was higher than other reported polymer-based membranes. SiO2 aerogel lowered PCL composite membrane’s surface energy. The triple curvature structure composed of microspheres, nanospheres, and nanofibers produced on PCL/SiO2-a0.5 membranes endowed the excellent roughness of the surface. Also, the inner structure of the PCL/SiO2-a0.5 composite membrane composed of micro–nano spheres, nanofibers, and microfibers increased the porosity of the separation membrane, which would provide more adsorption space. The PCL/SiO2-a0.5 composite membrane as a separator for surfactant-stabilized emulsions of water-in-oil showed ultrahigh separation flux and efficiency. Meanwhile, the PCL/SiO2-a0.5 composite membrane had an outstanding chemical resistance, self-cleaning ability, and good reusability. The composite membranes reported in this work as eco-friendly separation materials possessed all these characters in oil/water separation. This research proposed a very simple method to design eco-friendly high-efficiency separators through the construction of the alternated micro–nano hierarchical structure.