Synthesis of superhydrophobic silica nanofibrous membranes with robust thermal stability and flexibility via in situ polymerization

Superhydrophobic silica nanofibrous membranes exhibiting robust thermal stability and flexibility were prepared by a facile combination of electrospun silica nanofibers and a novel in situ polymerized fluorinated polybenzoxazine (F-PBZ) functional layer that incorporated SiO2 nanoparticles (SiO2 NPs). By using F-PBZ/SiO2 NP modification, the pristine hydrophilic silica nanofibrous membranes were endowed with superhydrophobicity with a water contact angle (WCA) of up to 161 degrees. Surface morphological studies have revealed that the wettability of resultant membranes could be manipulated by tuning the surface composition as well as the hierarchical structures. Quantitative fractal dimension analysis using the N-2 adsorption method has confirmed the correlation between hierarchical roughness and WCA for the modified membranes. Furthermore, the as-prepared membranes exhibited high thermal stability (450 degrees C), good flexibility (0.0127 gf cm), and comparable tensile strength (2.58 MPa), suggesting their use as promising materials for a variety of potential applications in high-temperature filtration, self-cleaning coatings, catalyst carriers, etc., and also provided new insight into the design and development of functional nanofibrous membranes through F-PBZ modification.