Study On The Dispersion Of Functionalized Graphene

Graphene owns excellent electrical,thermal,mechanical performance,it has been considered the most prospective carbon materials in 21 st century,because it can significantly improve the properties of sensor,batteries,super capacitors,and composite materials.However,the strong van der Waals force between layers of graphene and π-π stacking lead it easy to aggregate.It is well known that the excellent properties of graphene is associated with its unique two dimensional structure,only single layer or fewer layers graphene is excepted.In order to restrain aggregation of graphene,covalent and non-covalent functionalization was put forward.The surface functionalization will affect the surface properties of graphene and then has effect on its dispersion in solvents and compatibility with polymer.In this paper,graphene was surface functionalized by covalent and non-covalent,then their dispersion in solvents was explored.Hansen solubility parameters(HSPs)of studied graphene were calculated according their dispersion.The compatibility between graphene and epoxy was studies by HSPs theory.The main contents of this thesis are as follows:1.Graphene was non-covalent functionalized by four kinds of surfactants(SDBS,BS14,CPC,TX-100),bio-macromolecule(SA),polymer(PVP),and covalent functionalized by surfactant(OA),bio-macromolecule(LZ),polymer(PANI).SEM,XPS,Raman,XRD were used to characterize graphene was successfully functionalized.2.The dispersion of functionalized graphene in solvents was explored and recorded through digital images.HSPs of functionalized graphene were calculated according their dispersion.The results indicated through functionalization,dispersion of graphene in solvents and their HSPs were changed significantly.3.The dispersion of graphene in mixed solvents was explored.Experimental results indicated that the dispersion of graphene in different mixed solvents is disparate.When the mixed solvents has similar HSPs with target solvent,in most instances,graphene has similar dispersion in them,HSPs play important role in dispersion,but it is not the only factor which affect graphene dispersion.4.Graphene was prepared by three different reduction methods and functionalized.We found that the morphology,defect density,reduction degree and dispersion of graphene were associated with reduction method.Through functionalization,the dispersion and HSPs of graphene were changed significantly.5.The compatibility between studied graphene with polymer was researched using HSPs theory,and the dispersion state of studied graphene in polymer matrix was observed by Light optical microscope(LOM).The predicted results are in agreed with real dispersion of graphene in epoxy.Dispersion of graphene in epoxy will improved when it was functionalized by SDBS and CPC,and improving the dispersion of graphene in epoxy can enhance the thermal stability of composites.