Preparation of Fluorine‐Free Waterproof and Breathable Electrospun Nanofibrous Membranes via Thiol‐ene Click Reaction

Abstract

Clothes that are comfortable and functional are important in daily life; however, the manufacture of fluorine‐free functional fabrics with excellent waterproofness and breathability using simple and environmentally friendly methods still presents several technical challenges. Currently, the ultraviolet (UV) radiation‐initiated thiol‐ene click reaction is used for the construction of hydrophobic surfaces due to its high efficiency and the mild reaction conditions involved. Therefore, in this work, the electrospinning technique and the UV‐initiated thiol‐ene click reaction to introduce hydrophobic octadecanethiol (thiol) and 2,4,6,8‐tetramethyl‐2,4,6,8‐tetra‐vinylcyclotetrasiloxane (TMTVSi) into the silicon‐based polyurethane/polymethyl methacrylate (Si‐PU/PMMA) nanofibrous membranes is combined. After UV irradiation, the sulfhydryl groups of the thiol react with the carbon–carbon double bond of the TMTVSi, resulting in cross‐linking between the nanofibers. The fluorine‐free Si‐PU/PMMA/TMTVSi‐thiol‐30 waterproof and breathable electrospun nanofibrous membranes are observed to show excellent properties, which include a hydrostatic pressure of 64.43 kPa, water vapor transmittance (WVT) rate of 7879 g m−2 d−1, and robust tensile stress of 10.04 MPa, all of which enable the membrane to be widely used in the field of protective garments and oil–water separation.

Polyurethane-Coated Polyaniline/SiO2 Nanoparticle Electrospun Nanofiber Membranes for Waterproof and Moisture-Permeable Materials

“… Correspondingly, as shown in Figure b, with increasing ratio, the WVTR of the fiber membrane increased from 7.2 to 7.8 kg·m 2 ·d –1 but the air permeability decreased from 140 to 30 mm·s –1 . So, according to the above discussion, it was concluded that the air permeability had a behavior similar to that of the pore size and the WVTR had a behavior similar to that of the porosity of the fibrous membrane. , …”

“…So, according to the above discussion, it was concluded that the air permeability had a behavior similar to that of the pore size and the WVTR had a behavior similar to that of the porosity of the fibrous membrane. 33,34 The WCA is an important index to evaluate the hydrophobicity, which was a precondition for materials used in many fields. 20 For the PAN/SiO 2 −PU composite fiber membrane, the WCA increased with the increased ratio (Figure 4c) and reached a maximum of 137°when the ratio was 5:1 because of the maximum content of the Si element on the fiber surface at that moment (Figure 3g).…”

Cross-linking electrospinning

“…Briefly, an Si-PU/polymethyl methacrylate (PMMA) solution containing octadecanethiol, 2,4,6,8-tetramethyl-2,4,6,8-tetra-vinylcyclotetrasiloxane (TMTVSi), and 2,2-dimethoxy-2-phenylacetophenone (DMPA) was e-spun to form a composite fiber membrane. 50 The cross-linking was completed under UV irradiation by a thiol–ene reaction. After cross-linking, the introduction of octadecanethiol (hydrophobic chain) could endow the membrane with waterproofness and improved tensile strength (10.0 MPa at 30 wt% thiol content).…”

Fluorine-Free, Highly Durable Waterproof and Breathable Fibrous Membrane with Self-Clean Performance

“…The modified membranes have obtained super-hydrophobic surfaces (above 150°) and excellent self-cleaning properties [ 4 , 25 , 34 , 39 ]. However, hard dispersion of nano fillers in the spinning solution not only causes blockage of the nozzle but also forms random aggregation in the fiber [ 40 ], leading to performance deterioration of the membrane. Apparently, aftertreatment using coating methods can adjust the type, content, and orientation of the nanomaterials conveniently.…”