Fabrication And Properties Of Cellulose/Gtaphene Nanocomposite Materials

As the most abundant and renewable nature polymer in the world,cellulose is absorbed increasingly attention.Recently,the appearance of room temperature ionic liquids(ILs)solves the problem of dissolving cellulose,providing the possibilty to fabricate cellulose-based nanocomposite materials with high performances through green methods.Graphene,with one atom thick perfect honeycomb networK of sp2-bonded carbon,has attracted tremendous attention with excellent mechanical,thermal and electrical properties.In the realm of polymer,as the nano modified filler,grapheme has been more and more widely used.Therefore,this work is focused on the preparation of cellulose/grapheme nanocomposite material to improve the mechanical properties or some functional properties based on ILs.In order to achieve this target,we open up the study including the synthesis of the grapheme,the composite craft of cellulose/grapheme nanocomposite materials and the relationships between the structure and properties of the as-prepared nanocomposites materials.The main research contents and achievements are as follows:1)The physical and mechanical structure changes of graphene oxide(GO)in the thermal reduction process has been studied using in situ FTIR and synchrotron radiation WAXD techniques.The results indicate that the reduction process of GO is described with the four steps:(a)the dehydration period;(b)the stable period;(c)the initial reduction period;(d)the accelerated reduction period.On the basis of these results,we have disclosed and correlated the relationship between the thermally induced changes in interlayer distance and the chemical structure,providing guidance for the preparation of grapheme extremely exfoliated.2)We present a green and facile routing for synthesis of reduced grapheme oxide based on 1Ls,1-allyl-3-methylimidazolium chloride(AmimC1).The outstanding character of the proposed synthesis craft lies in the simply mixing of GO aqueous with ILs of high temperature can subtly bring about a well dispersed RGO in adopted ILs(IRGO)with the synchronous evaporation of water.It is proved that the IRGO can definitely dispersed in ILs with the aid of various techniques.It is worthy of noting that filtering scrubbed IRGO shows good redispersibility in water and DMF,with the zeta position up to +39.07 eV in water,and the max concentration up to 0.6 mg/ml.3)Considering the untreated cellulose can be dissolved rapidly in AmimCl,we have prepared cellulose/graphene nanocomposites with the help of the as-prepared stable dispersed IRGO/AmimCl,and systemly studied their structure and properties.The results show that the thermal and mechanical properties of regenerated cellulose/IRGO nanocomposites films are improved obviously with the incorporation of IRGO sheets.Furthermore,those properties are also relevant to the cellulose solubility of the nanocomposites.Moreover,the influence of the content of IRGO sheets on the structure and properties of cellulose/IRGO nanocomposites has also been studied.The lower the content of IRGO sheets,the more extraordinary improvements of thermal and mechanical properties,due to the homogeneous dispersibility of IRGO sheets and the small size of regenerated cellulose fibrils.4)However,the process of fabricating the cellulose/graphene nanocomposite materials is excessively complicated using GO,besides,the conductivity of the resulted nanocomposites is extremely low.Thence,we fabricated cellulose/grapheme nanocomposite materials from natural graphite.The research findings show that homogenous graphene sheets can be directly exfoliated from natural graphite in high temperature AmimCl with the aid of a small amount of cellulose,and the resulted graphene sheets that can be stably dispersed in AmimCl have average thickness of~2 layers.It is noteworthy that the small amount of cellulose can notably reduce the viscosity of AmimCl,which may shed some light on the practical application of AmimCl.On the basis of the graphene/AmimCl solution,we further fabricate a series of cellulose/graphene nanocomposites with different concentrations of graphene sheets.When the content of graphene sheets is 0.98 wt.%,the transparency of the nanocomposite film reaches 88.3%with remaining the flexibility of cellulose matrix,as well as the conductivity 0.54 S m-1.In addition,the thermal stability and mechanical properties ofthe nanocomposite films are increasingly improved with the higher the graphene contents(<1 wt.%).Thereby,the as-prepared flexible,transparent and conductive cellulose/graphene nanocomposite films would have wide application prespects in solar cells,transparency electrode materials and so forth.