Preparation of breathable superhydrophobic PU/SNPs hybrid nanowebs by electrospinning

Abstract

Non-fluorinated polyurethane (PU)/SiO2-nanoparticles (SNPs) composite nanowebs with superhydrophobic and breathable properties were prepared by electrospinning, using n-dodecyltrimethoxysilane (DTMS) as water repellent chemicals. The fiber morphology was examined by field emission scanning electron microscopy. The average fiber diameter was about 600-800nm with 1wt-6wt % SNPs, and they were observed spread on all of fiber surfaces. The combination of the hierarchical surface roughness of PU/ SNPs nanowebs yielded a stable superhydophobicity with water contact angles as high as 159° and shedding angle as low as 5° by electrospinning and chemical vapor deposition (CVD)-coating process. The water contact angle (WCA) of pure PU nanowebs and PU/SNPs nanowebs increased from 131° to 151°, which could be attributed to the increasing size of the fiber diameter leading to increased roughness of the membranes. Besides, adding SNPs had positive effects on porosity of nanowebs, and thus of can be regarded as super breathable nanowebs. The water vapor transmission rate test showed that the moisture permeability of PU/SNPs was the highest. After through the treatment of DTMS hydrophobic surface-modification, the air permeability and water vapor transmission of the PU-SNPs-CVD nanowebs decreased comparing with the PU-SNPs nanowebs.