Preparation And Research Of Waterborne Polyurethane Nanofiber Materials Modified By Fluorosilicon Based On Electrospinning

Waterproof and moisture-permeable fabrics can resist liquid water penetration and transmit water vapor,and have broad development prospects in protective clothing,medical and health and other fields.Among them,nanofiber membranes based on electrospinning technology have the advantages of small pore size,high porosity and excellent pore penetration,and are one of the effective methods for preparing waterproof and moisture-permeable fabrics.However,at present,organic solvents are mostly used in the preparation of electrospinning nanofiber membranes,which will not only cause pollution to the environment,but also cause harm to human health by toxic solvents remaining in nanofiber membranes;Secondly,although there have been some reports on the preparation of nanofiber membranes by green solvent method,the raw materials are mostly water-soluble polymers,resulting in poor waterproof and moisture permeability.Therefore,the preparation of nanofiber membranes with waterproof and hygroscopic properties and no toxic solvents by combining electrospinning technology has important scientific significance and application value.In this work,in view of the various challenges faced by electrospinning technology in preparing nanofiber membranes,low surface energy molecules such as fluorine and silicon are introduced into the polyurethane molecular chain to prepare waterborne polyurethane modified with fluorine and silicon.A series of waterborne polyurethane electrospinning nanofiber membranes based on green solvents were prepared as raw materials,and the molding process of using electrospinning technology to prepare nanofiber membranes using waterborne polyurethane and green solvents as raw materials was studied,he transport law of water molecules and air in nanofiber membranes was revealed,and the relationship between nanofiber membrane structure and waterproof,breathable,moisture permeable and mechanical properties was systematically analyzed.The main research contents are as follows:（1）Reparation and performance study of fluorine-modified waterborne polyurethane green nanofiber membrane.Firstly,a polyol polymer（PEE-co-PPO）with perfluorinated chain on the side group was prepared by halogenation reaction and cationic polymerization reaction,and a series of anionic waterborne polyurethanes with different fluorine content were prepared by halogenation reaction and cationic polymerization reaction,and the molecular structure of PEE-co-PPO and waterborne polyurethane was accurately characterized.Then,nanofiber membranes were prepared using waterborne polyurethane with different fluorine content as spinning liquid,and the effects of fluorine content,green solvent（ethanol）addition and nitrogen propidine crosslinker content on the microstructure and waterproof and moisture permeability of nanospinning fiber membranes were explored.With the addition of 3 wt%fluorine content,75 wt%ethanol content and 3 wt%aziridine crosslinker,the hydrophobic chain segment migrated to the surface of the nanofiber membrane after high temperature crosslinking,giving the nanofiber membrane stable hydrophobic properties,and its contact angle was as high as139°.At the same time,the nanofiber membrane has the characteristics of small pore size and high porosity,so that its hydrostatic pressure is as high as 84.16 k Pa,the moisture permeability performance reaches 12.92 kg·m^-2·d^-1,the air permeability reaches 5.11mm·s^-1,and has excellent mechanical properties,its tensile strength reaches 13.41 MPa,and the elongation at break is 329.4%.Therefore,based on the excellent waterproof and moisture permeability of the prepared nanofiber membrane,it can be widely used in waterproof and breathable clothing in harsh environments,bringing comfortable body feeling to the human body.（2）Preparation and performance study of silicon-modified waterborne polyurethane green nanofiber membrane.Firstly,by the lateral modification of the parahydroxyl polybutadiene sidegroup,the polydimethylsiloxane（Mn=5000 g/mol）polymer was modified by synthesizing a polymer with a glycol structure with a side group with low surface energy silicon(HTPB_fur-PDMS-Ma I),doping it into waterborne polyurethane as a partial soft segment,and introducing a small amount of PEG into the waterborne polyurethane emulsion while doping a small amount of nitropropidine crosslinker to prepare a spinning solution,so that the molecular chain in it has a certain entanglement.The nanofiber membrane was prepared by electrospinning technology,with silicon content of 20 wt%,1 wt%PEG content and 4 wt%aziridine crosslinker,and the chemical reaction between the crosslinker and waterborne polyurethane by high temperature heating constructed a three-dimensional cross-linked network structure,at the same time,the hydrophobic chain segment migrated to the surface of the fiber membrane through heat induction,so that the nanofiber membrane has a water contact angle of up to 145.7°,and the nanofiber membrane has the characteristics of small pore size and high porosity,so that its moisture permeability reaches 12.65 kg·m^-2·d^-1,air permeability of 14.21 mm·s^-1,and has excellent mechanical properties,its tensile strength reaches 3.67 MPa,elongation at break is 302.4%.Therefore,the nanofiber membrane based on the obtained nanofiber has excellent mechanical properties and waterproof and moisture permeability,and can be widely used in the development of medical and health fields.