Construction Of Multi-level Micro-nano Fiber Double Network And Study Of Air Filtration Performanc

The haze weather caused by Particulate Matter（PM）not only brings inconvenience to People’s Daily life,transportation and production operations,but also causes serious damage to people’s health.Fiber filter material has become the most widely used air filter materials because of its high porosity,controllable morphology and simple processing technology.However,the existing commercial fiber air filter materials such as melt-blown electret filter materials mainly rely on electrostatic adsorption to improve the filtration efficiency.Electrospinning technology has gradually become popular in the field of air filtration due to its advantages of fine fiber diameter and small pore distribution,but its bulk density causes high pressure drop.Therefore,the development of new filter materials has become one of the important issues concerning people’s livelihood.In this study,secondary supramolecular nanowires were generated in the solution blowing nanofiber net and polylactic acid melt-blown fabric by the self-assembly characteristics of low molecule organic gelators,and different kinds of multistage structure micro/nano fiber air filter materials were constructed.The specific contents are as follows:The low molecular organic gelators DMDBS was self-assembled in the solution blowing nanofiber network to form secondary supramolecular nanofibers with a diameter of 10-30 nm,and a multilevel double nanofiber network was prepared.The structure of the fiber network can be regulated by adjusting the concentration of the self-assembled solution.The assembled process of the secondary nanofiber network follows the adsorption-nucleation-growth mechanism.It is found that the introduction of the secondary nanofiber network improves the mechanical properties of the solution blowing nanofiber network,it reduces its pore size,and improves the filtration efficiency（up to 99.99%）.Thanks to the ultra-fine diameter of secondary nanofibers,the filtration resistance of the double nanofiber network does not increase significantly（36 Pa）,the QF is 0.177 Pa^-1,and it has showed good long-term filtration performance.In addition,the double nanofiber network has good moisture permeability and can provide good comfort for individual protection.Aiming at the problems of unstable air filtration performance and easy attenuation of electret charge of melt-blown fabric,as well as the demand for renewable bio-based raw materials,we applied a newly synthesized ligand L coordinated with silver ions in the PLA melt blown fabric.The PLA melt-blown multilevel fiber air filter material has showed good air permeability,high mechanical properties and fracture strength as high as 10.09 MPa.In terms of filtration performance,the melt-blown multilevel air filter material showed higher filtration efficiency of 99.12%and low air resistance of 44 Pa.Besides,due to the introduction of silver ions,the bacteriostatic rate of Escherichia coli and Staphylococcus aureus was up to 99.99%.