Functional Cellulose/Graphene Composites:Fabrication And Characterization

Cellulose is the basic component of the cell wall of plants,and thereby,regarded as the most abundant natural polymer.The excellent electrical and thermal conductivity of graphene,as well as mechanical performance,make it very prevailing to blend with cellulose and its derivatives as an ideal nanoscale filler for fabricating functional composite hydrogels.But so far,there are still some challenges,mainly focusing on how to realize the efficient and large-scale fabrication of cellulose/graphene composites for the applications of the adsorption of pollutants as well as electromagnetic interference shielding.To solve these problems,some novel researches have been conducted in this thesis as follows:(1)Carboxymethyl cellulose sodium(CMC)/graphene oxide(GO)composite hydrogel microspheres were fabricated via the combination of solution blending and spray drying,by using CMC as a polymer matrix,citric acid(CA)as a green cross-linker,GO as a functional nano-filler.The incorporation of GO made CMC composite microspheres to be one sort of broad-spectrum adsorbent,which could adsorb not only ionic organic dyes via electrostatic interaction,but also heavy metal ions via electrostatic interaction and surface complexation.More importantly,the microsphere structure endowed CMC/GO composites with high surface area,leading to a high rate of adsorption and generally reaching to the adsorption equilibrium for pollutant molds within 30 min.(2)Ferroferric oxide(Fe3O4)nanoparticles were synthesized and deposited in-situ on the surface of GO by means ofcoprecipitation method,resulting in GO@Fe3O4 composite,which was then employed to blend with CMC for fabricating CMC/GO@Fe3O4 composite hydrogel micro spheres via spray drying.Finally,the influence of Fe3O4 nanoparticles on the adsorption behavior of heavy metal ions was investigated with chromium(Cr6+)as a typical model The results indicated that the introduction of Fe3O4 nanoparticle not only improved the adsorption capacity of CMC/GO microspheres for Cr6+,but also endowed the samples with excellent magnetic property.This feature makes our CMC/GO microspheres a very promising adsorbent that can be facilely recycled under an external magnetic field.(3)Flexible CMC/Graphene@Fe3O4 composite films with high-performance electromagnetic interference(EMI)shielding effectiveness(SE)as well as microwave-absorbing(MA)property were fabricated by blending GO@Fe3O4 composite with CMC.With graphene sheets as a shielding agent and Fe3O4 particles as a microwave absorber,-94-96%of incident electromagnetic power in X band(8.2-12.4 GHz)could be shielded by the CMC composite with 9.6 wt%Graphene@Fe3O4 via reflection and adsorption.Moreover,the EMI SE and MA property of CMC composites could be facilely tuned by adjusting the relative content of graphene to Fe3O4 in Graphene@Fe3O4.