Flexible, Super-hydrophobic, High Temperature Resistant, Inorganic Nanofibrous Membranes Via Electrospinning

Recently,the electrospun fibrous mats with hierarchical micro/nanostructures have been widely investigated as the super-hydrophobic surfaces inspired by the lotus effect.However,to get the flexible,super-hydrophobic,and high heat resistant electrospun mats used in extreme environments still is a big challenge left since the flexible polymer mats could not against the high temperature,and the inorganic mats are too fragile.In this study,for the first time,we fabricated a flexible,super-hydrophobic and high heat resistant mats by fluoroalkylsilane(FAS) modification of electrospun pure SiO₂ nanofibrous mats. The inorganic SiO₂ nanofibrous mats were obtained via electrospinning the blend solution of poly(vinyl alcohol)(PVA) and tetraethoxysilane,followed by the calcination to remove the organic component.The resultant samples were characterized by scanning electron microscopy (SEM),Fourier transform-infrared spectroscopy,contact angle meter,X-ray diffraction(XRD) and differential scanning calorimetry respectively.The results of SEM images showed that the as-prepared and FAS modified SiO₂ fibers were both randomly oriented as nonwoven membranes with fiber diameter in the range of 150 to 500 nm.From XRD analyses,the SiO₂ nanofibrous mats were amorphous.After the FAS modification,the surface wettability of SiO₂ mats was converted from super-hydrophilic to super-hydrophobic and oleophobic.It showed a water contact angle (WCA) of 154°and an oil contact angle(OCA) of 143°.Additionally,the FAS modified inorganic fibrous mats exhibited a good high heat resistance,it could keep the hydrophobicity with a WCA of 138°and oleophobicity with an OCA of 132°,even after the heat treatment at 450℃.The flexibility of the FAS modified SiO₂ nanofibrous mats was studied by mechanical properties tests. After the bending test,the mats could still keep their good amphiphobicity.