Preparation Of Graphene-based Nanocomposite & Research And Application In Biomedical Scaffold

Graphene as a new two-dimensional nano materials,has a perfect crystal structure,since its discovery,graphene with its unique electrical,optical,thermal and mechanical properties,make its in electronic devices,field emission materials,composite materials,gas sensors,energy storage and environmental science and other fields has a broad application prospect.Graphene has been as a kind of ideal nano filler to the preparation of polymer composites,but so far,the oxidation reduction method for the preparation of graphene materials,and how to graphene evenly dispersed in polymer matrix preparation into uniform nano graphene materials still bothering people.This dissertation revolves around these problems,using a variety of new methods for preparation of graphene and graphene nanocomposites for preparation,and preparation of polymer nanocomposites and biomedical applications of biological scaffold aspects of interdisciplinary.The main research contents and conclusions are as follows:1)first,because the covalent modification of REDOX graphene can be stably suspended in water solvent,so in order to be able to and the preparation of polymer nanocomposites,we chose easily soluble in water polymer,PVA.Poly(sodium styrene sulfonate)(PSS)for graphene oxide(GO)to the covalent bonding surface modification,and guarantee the integrity of its structure,and then GO to restore,in the process of reduction,GO no reunion because of lost the oxygen-containing groups,after the reduction,reduction of graphene oxide(rGO)under the action of PSS,still maintained a state of suspension in the solvent of water.Because of PSS and graphene has a strong adsorption,and through the PI-PI bond connection,strong nuclear force,we can get through the experiment,under the action of PSS,graphene reunion phenomenon did not appear after a REDOX reaction,and after a long enough period of time,still keep the state of suspension,showed that PSS adsorption has a strong stability of graphene.In addition,the oxidized GO also passed the tests of Raman,ft-ir and XPS,which represented the reaction process.2)mix the suspensions of GO and rGO with polyvinyl alcohol(PVA)solution to prepare graphene nanocomposites.Raman and infrared spectrum results show a powerful interaction between PVA and rGO,such as pi-pi,hydrogen bonding,and ch-pi.After testing,the DSC analysis of composite materials was found.With the addition of GO or rGO,the molecular chains in the composites were restricted,and the glass transition temperature was improved.In particular,the addition of rGO makes the glass transition temperature of composite materials up to 109.The melting process has also been changed a lot.Since GO or rGO both have thermal conductivity,rGO has reduced the partial sp2 structure to make the rGO heat conduction function stronger.By the XRD characterization,the addition of graphene destroys the crystal structure and the PVA cannot form a crystalline structure.The amount of rGO only 0.1 wt%can be increased by 55%of young's modulus of composite material.Adding 0.3 wt%can increase the tensile strength by 48%.3)The prepared PVA/GO and PVA/rGO nanocomposites were used in biological scaffolds,and GO or rGO was added to the PVA matrix,which changed the surface properties of the original scaffolds.The surface roughness of the biological scaffold is reduced by adding GO,while the surface roughness of the scaffold increases after the addition of rGO.The matrix PVA has good hydrophilicity.After testing,it is found that the hydrophilicity of the scaffold decreases with the addition of GO and rGO,and the hydrophilicity of the scaffold surface decreases with the increase of GO and rGO.After testing the survival of mouse embryonic fibroblast(NIH-3T3)by biological scaffolds,it was found that NIH-3T3 cells were more easily adsorbed on biological scaffolds containing GO and rGO,especially on rGO containing biological scaffolds.4)The growth of NIH-3T3 cells is affected by the extracellular environment.We found that the growth of NIH-3T3 cells was easily affected by electric field.Conductive graphene composites were used as cell scaffolds.In order to guide the growth direction and growth mode of NIH-3T3 cells,a certain electric field was added to the cells.The electrical conductivity of PVA/rGO increased with the increase of rGO.Under the influence of electric field,NIH-3T3 cells were cultured in cell scaffold composite conductive graphene,can be found in the cell scaffold plays a positive role in the adsorption conductivity on the cell scaffold,PVA/rGO scaffolds with higher electrical conductivity,adsorption cell number increases,and cells have certain orientation in the direction of electric field.In the absence of an electric field,the adsorbability of the cells to the scaffold became lower.Anyhow,graphene nanocomposites can be used in the field of biological scaffold,conductivity of graphene composites to culture cells,under the action of electric field on the adsorption and cell growth has a certain guiding role.