Size Fractionation Of Graphene Oxide And Their Applications On Fibers And Aerogels

Owing to its unique properties,graphene oxides(GO)has enjoyed significant attention for application in many fields such as fibers,aerogels,biosensors and conducting electrodes.However,regular GO is not enough to satisfy the application requirements,so it is necessary to obtain a graphene with suitable size distribution in order to prepare materials possessing better properties.Restricted by current size fractionation technologies,it is still a great challenge to obtain GO sheets in a relatively narrow size distribution by using a simple method.Here,we used a facile size fractionation process of GO sheets assisted by circular flow,then,different sized GO application were studied mainly in two respects:the composite fibers of small sized GO(SGO)reinforced polyamide 6(PA6)matrix with outstanding tensile strength with high toughness;the aerogels of honeycomb-like structure made of large sized GO(LGO)with excellent adsorption,filtration and regeneration properties.The main research details are shown as follows.1.With the help of hydrogen gas(H2)bubbles generating from metallic replacement reaction,continuous turbulence formed a circular flow in a special tubular container,which made it possible to fractionate different sized GO sheets.By using this process,crude GO(CGO)sheets were facilely separated into three size ranges:LGO(>20 ?m),MGO(2-20 ?m)and SGO(<2 ?m).X-ray photoelectron energy spectra(XPS)results show LGO surface has fewer defects in the structure than MGO,SGO and CGO.2.Caprolactam(CPL)was polymerized with introduction of PA6-grafted GO to prepare PA6/PA6-grafted GO(g-GO)composite that were melting-spun into composite fibers.The results show that dispersibility of g-GO in the composite increases with the decrease of its size,and particularly,PA6 grafted SGO(g-SGO)disperse much more uniformly than the other sized g-GO.As a result,PA6/g-SGO composite(SPA)fiber has outstanding tensile strength and toughness.3.Based on the different sized GO,different graphene aerogels were prepared by hydrothermal method and freeze drying method,respectively.The graphene aerogels prepared by LGO precursors possess stronger adsorption capacity for strong oxidizing agents and oil.4.A facile fabrication strategy towards the stable honeycomb-like structured GO aerogel(LTA),made of LGO hybrided with modified tourmaline nanoparticles(mTNPs)via freeze casting,was presented.The formation mechanism,the filtration and absorption efficiency for PM2.5,and recycling performance of the aerogels were studied.The results show that the ordered pore structure LTA possess excellent mechanical durability and deformation restorability.As an adsorbent,LTA has obvious excellent filtration efficiency for PM2.5.When mTNPs loading is 5wt%,filtration efficiency for PM2.5 of the aerogel is up to 95.1%in the first filtration cycle.More importantly,the aerogel can be used repeatedly after simple recycling process.