Preparation And Properties Of Fluorine-free Environmental Protection Waterproof And Breathable Electrospun Nanofibrous Membrane

The rapid development of science and technology has gradually extended the application of textiles.In this trend,apart from traditional fabrics merely used for keeping warm,some textiles with special functions and excellent performance obtained fast growth because they can better meet people’s needs.By virtue of a waterproof and breathable membrane,the waterproof and breathable fabric,as a functional textile,can not only resist the invasion of external liquid water and protect the human body,but also quickly diffuse sweat vapor into the air so as to ensure wearing comfort.At present,the fluorinated microporous membrane is the most commonly used waterproof and breathable membrane in the market.Despite its excellent waterproof performance,which are potentially harmful to both human health and ecological environment.In view of this,by means of selecting the fluorine-free silicone-modified polyurethane（Si-PU）and polymethyl methacrylate（PMMA）as raw materials,the waterproof and breathable nanofibrous membrane is prepared through the electrospinning technology combined with two finishing methods of heating and UV light irradiation.Based on changing the heat treatment temperature of nanofibrous membrane,as well as the content of binder and chemical cross-linking agent,the pore diameter and surface wettability of the nanofibrous membrane can be adjusted systematically.In this way,the waterproof and breathable membrane with good comprehensive waterproofness,high moisture permeability and excellent mechanical properties was obtained.In this research,polypropylene butyral（PVB）with a low softening point was firstly introduced into the Si-PU/PMMA spinning solution as a binder;secondly,the nanofibrous membrane was further optimized by heat treatment,and then the Si-PU/PMMA/PVB waterproof and breathable membrane with physical welding structure was prepared.According to the study of the influences of heat treatment temperature and PVB content on the morphology and properties of the nanofibrous membrane,the Si-PU/PMMA/PVB waterproof and breathable membrane shows the best comprehensive performance at the heat treatment temperature of 80℃and the relative PVB content of 40%:with the water pressure resistance value at 65.29 k Pa,water vapor transmittance rate of 6677 g m^-2 d^-1,and breaking strength at 11.4 MPa.During the process of enhancing waterproof and breathable via thermally induced fiber fusion,a series of problems including poor hand feel,high energy consumption and complicated equipment were brought about.Thus,for the sake of reducing production energy consumption and maintaining the soft hand feel of nanofibrous membranes,this research,on the basis of membrane research,introduced octadecanethiol（thiol）and TMTVSi as hydrophobic agents and chemical cross-linking agents to build a hydrophobic surface and improve the waterproofness.In addition,under the UV light irradiation,thiol-ene click chemical reaction occurred between thiol and TMTVSi in the prepared nanofiber membrane,so that the chemical cross-linking between nanofibers was generated and the maximum pore diameter of nanofibrous membrane was reduced,thereby further improving the waterproofness of the nanofibrous membrane.The Si-PU/PMMA/TMTVSi-thiol-30nanofibrous membrane prepared by electrospinning technology combined with thiol-ene click chemical reaction can withstand up to 64.43 k Pa of water pressure,water vapor transmittance rate of 7879 g m^-2 d^-1 and 10.04 MPa of breaking strength,so it has the potential to be used in the fields of separation membranes,self-cleaning materials and protective clothing.