Recently, waterproof and breathable materials have attracted
extensive
attention and have been used in a broad range of applications such
as clothing, sports equipment, medical hygiene products, and other
fields. In this study, an efficient chemical modification method was
suggested to prepare polyurethane/SiO2 nanofibrous membranes
with superhydrophobicity and durability. A polyurethane emulsion was
treated with 4,4′-methylenebis(phenyl isocyanate) and 3-aminopropyltriethoxysilane.
This emulsion process was combined with the emulsion electrospinning
technique and a hydrothermal-assisted sol–gel process to prepare
superhydrophobic polyurethane nanofibrous membranes. The final polyurethane/SiO2 nanofibrous membranes exhibited a hydrostatic pressure of
8.02 kPa, an air permeability of 3.89 mms–1, and
a water vapor transmission rate of 10.12 kg m–2 d–1. Results also showed that the water contact angle
of the nanofibrous membranes reached 154°, and the stress and
strain were 5.3 MPa and 198%, respectively. In addition, the adhesion
between SiO2 and the PU nanofibrous membranes was high,
and the weight loss rate of SiO2 remained at approximately
9.72% after the ultrasonic cleaning time exceeded 24 h. These results
suggested that the PU/SiO2 nanofibrous membranes were expected
to provide a new perspective for waterproofing and moisture permeability.
In this paper, hydrophobic PAN/SiO 2 −PU composite nanofiber membranes were prepared by coaxial electrospinning combined with a hydrothermal method. The effects of the feeding rate ratio of the shell (PAN/SiO 2 ) solution and the core (PU) solution, the content of SiO 2 in the shell solution, and the hydrothermal time on the composite nanofiber membrane were analyzed. The results showed that when the feeding rate ratio of the shell−core solution was 5:1 and the SiO 2 content in the shell solution was 60 mg•mL −1 , the PAN/SiO 2 −PU nanofiber presented a uniform diameter and an obvious shell−core structure, and the Si element was uniformly distributed on the fiber surface. After hydrothermal treatment, the surface water contact angle of the PAN/SiO 2 −PU composite nanofiber membrane reached 152°, and the water vapor transmission rate was 8.48 kg•m 2 •d −1 . In addition, the average solar reflectance of the composite nanofiber membrane was as high as 60.29%, and the temperature difference between the PAN/SiO 2 −PU and PAN−PU composite nanofiber membranes was 4.5 °C, indicating an obvious radiative cooling effect.
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