Preparation Of Functionalized Graphene And The Application In Polymer Materials

Graphene,a two-dimensional carbon nanomaterial composed of sp2 bonding carbon atoms,is one of the carbon materials with better performance at present.But poor dispersion of graphene in water or organic solvent greatly restricts its application.Graphene oxide(GO)is prepared by strong oxidation of graphene.There are oxygen-containing functional groups such as hydroxyl,carboxyl and carbonyl groups on the surface of GO,which greatly improves its dispersion in aqueous solution system,but it still has poor dispersion in organic solvent and polymer system.In order to make GO better used in polymer composites and other fields,it is an effective way to functionalize the surface of GO.However,there are still some oxygen-containing functional groups on the surface of functionalized GO.And the number of these oxygen-containing functional groups can affect the lamellar state and properties of graphene,which may have a positive or negative effect on the comprehensive properties of epoxy resin composites.In addition,GO and functional graphene oxide(F-GO)have a great impact on the styrene polymerization system,thus changing the conversion of monomer,molecular weight and molecular weight distribution index of the product.The main contents and conclusions are as follows:(1)Graphene oxide was covalently modified with 3-Aminopropyl Trimethoxysilane(APS),and then reduced by hydrazine hydrate.And F-GO containing different amount of oxygen-containing groups was prepared by controlling the reduction time.Finally,XPS,Raman spectrum and other characterization methods and dispersion test were used.The results show that the number of oxygen-containing groups decreases with the increase of reduction time,and the enhancement of defect degree of F-GO slows down.And there was no difference between the dispersion of GO and F-GO in organic solvents.After reduction,the dispersion of F-GO increased significantly with the increase of reduction degree.(2)GO,F-GO,F-rGO with different reduction degree were used to prepare composite materials with epoxy resin,and their mechanical and thermal conductivity were tested.The results show that at 0.1 wt%filler content,the functionalization of GO can improve the mechanical property of the composite,and the mechanical property of the composite improves with the increase of reduction degree of F-GO,but its thermal conductivity shows the opposite trend.At 0.5 wt%and 1 wt%filler content,the functionalization of GO can improve the thermal conductivity of the composite,and the thermal conductivity of the composite improves with the increase of reduction degree of F-GO.When the filler content is 1 wt%,the thermal conductivity of F-rGO-3/EP is the largest and 17.3%higher than that of pure epoxy resin.(3)The effects of GO and F-GO on the conversion of styrene(St),molecular weight and molecular weight distribution of polystyrene(PS)were studied at different temperatures.The results show that the addition of GO and F-GO can reduce the conversion of PS,and increase the molecular weight and molecular weight distribution index of PS.But these effects gradually slow down with the increase of temperature.These phenomena happen because the large ?-conjugated system on the graphene oxide skeleton and the polar oxygen-containing groups on the surface attract the initiator and the free radicals in the reaction process,thus causing a series of changes in the polymerization system at different temperatures.