Electrospun fibrous membrane with controlled hierarchical structure and wettability for effective emulsion separation

Porous membranes are widely used for filtration, especially those with homogenous pore size and strong mechanical strength. Here, we develop a programmable electrospinning system and fabricate porous membranes consisted of orthogonally aligned nanofibers. The porous fibrous membranes possess more homogeneous pore size and stronger mechanical strength when compared to traditional porous membrane with disordered nanofibers. By physically modifying the membrane surface with PTFE nanoparticles, we obtain a filter membrane, which has both large oil contact angle in water and large water contact angle in oil. Synergism between hierarchical structure and surface property realizes a high separation efficiency of both oil-in-water and water-in-oil emulsions. The technique to control the structure of fibrous membrane, combined with the method to modify the surface of nanofibers, provides a great opportunity to design advanced fibrous membrane for various applications.