Interfacial Self‐Assembly and Waterborne Hydrophobic Emulsion Coating Toward Nanofibrous Membranes for Waterproof, Breathable, and Anti‐Fouling Applications

ABSTRACT Constructing superhydrophobic surfaces on nanofiber membranes while avoiding the destruction of porous structures in membranes is important for waterproof and breathable applications, yet has proven challenging. Herein, a novel interface self‐assembly strategy was proposed to create rough surface structures on the nanofibers, and an environment‐friendly waterborne hydrophobic coating was developed for interface hydrophobization. The interface self‐assembly strategy introduces branched poly(ethylenimine) (BPEI) as a bridging medium, which can mediate the assembly of TiO 2 nanoparticles on the nanofiber interface, thus enabling the formation of hierarchical rough structures. Meanwhile, the waterborne hydrophobic coating was prepared by self‐assembling organosilicon in an aqueous medium and coated on the nanofibers for surface hydrophobization. As a result, the rough surface structure and waterborne hydrophobic coating endowed the nanofibrous membranes with excellent superhydrophobic properties. The resultant hydrophobic nanofibrous membranes showed a high hydrostatic pressure of 8.8 kPa, a high water vapor transmission rate of 6.28 kg m −2 d −1 , an excellent air permeability of 12.81 mm s −1 , along with an exceptional anti‐fouling/self‐cleaning capacity, demonstrating their strong potential in waterproof and breathable applications.