Design,Preparation And Application Of Aramid Nanofiber-based Functional Composite Aerogels

Aerogel is a porous solid material composed of interconnected three-dimensional solid networks and filled with a large amount of gas.Its nano-scale structures,as well as physical and chemical properties endow aerogels with the advantages of high porosity,large surface area,and low density.It shows a wide range of applications and prospects in energy storage,adsorption,catalysis and many other fields.However,it is still a challenge via simple technique to prepare aerogels with high specific surface area,high porosity and multi-functions such as optical,electrical,thermal,and magnetic properties.Obviously,single-component aerogels are hardly meet the demand of multi-functionalization,but the combination of different materials can make the composite materials complement each component in performance and produce synergistic effects.Therefore,compounding has become the main direction for the development of multifunctional aerogels.Based on this,aramid 1414?trade name Kevlar?produced by Du Pont is selected as the matrix phase,which has excellent properties such as high strength,good thermal stability,light weight,and resistance to acids and alkalis.Different from the previous research,in this paper,the aramid fiber bundles were dispersed in dimethyl sulfoxide?DMSO?by deprotonation,and the aramid nanofiber?ANF?dispersion was obtained.Then,the composite aerogels were prepared from ANF and other high-performance nano-materials.The main research contents include:?1?ANF/CNT hybrid aerogels were prepared by mixing ANF and CNTs,blade coating,sol-gel processing and freeze-drying.Then,the hydrophobic coating of fluorocarbon?FC?was applied to make the aerogels with good hydrophobicity and performance.Due to the intermolecular forces and?-?stacking effect,CNTs and ANFs are well compounded.The obtained flexible FC-ANF/CNT aerogel films possess large specific surface area(232.8 m²·g^-1),high conductivity(230 S·m^-1),excellent hydrophobicity?137°?,excellent electric heating ability?112?at 10V?,high electromagnetic shielding?54 d B?,and high theoretical shielding efficiency?99.999%?,which can be applied to thermal management,electromagnetic protection and other aspects.?2?A wide band absorbing polypyrrole?PPy?was grown in-situ in the ANF framework,and then ANF/PPy aerogels were prepared by supercritical drying.The multiple hydrogen bonds between ANF and PPy enabled the composite aerogel with excellent mechanical properties,which have been proved in IR and Raman spectra.In addition,the composite aerogel also have high light-thermal conversion efficiency?82.5%?,sewage purification capacity,high solar-thermal evaporation?1.71kg/m²/h?.After 20 cycles of usage,it still show a stable water evaporation capacity.So this composite aerogel has a good application prospect in desalination.