Polymer-Graphene Composite Material:Preparation,characterization And Property

Planar graphene has been a hot spot in the research of carbon materials since its discovery.In addition,its excel ent electrical,thermal and mechanical properties have brought new breakthroughs in the field of various materials.Because the ?-? interactio n between graphene sheets,which makes it easy to precipitate in common solvents and is not conducive to dispersion,the application of graphene in many aspects is limited.In this study,graphene was taken as the research object.We made use of its characteristic conjugated structure by non-covalent and covalent methods to obtain modified graphene composites.And the dispersibility of the modified graphene in the solvents was improved and some new attempts were made in modifying graphene.1.Preparation,Characterization and Properties of CS-rGOCS-rGO was made by chitosan and graphene oxide.Four kinds of chitosan were were used to make non-covalent modfication with graphene by electrostatic attraction.After ultrasonic centrifugation,four kinds of complexes were obtained.The physical and chemical properties of the composites were characterized by FT-IR,TG,UV,Raman and so on.It was proved that chitosan was effectively compounded with graphene.The result of FT-IR shown that the wavenumber of the absorption peak decreases in the composites after the introduction of the graphene conjugated system.According to the XRD results,the d-spacing of the graphene films was increased and the characteristic structure of graphene was also observed by TEM and FE-SEM.In the range of pH 1.0 ~ 4.0,composites had good dispersibility.In pH 2.0,the dispersion of the complex was achieved the best.With the increase of pH value,the dispersibility of the composites decreased and has a certain pH sensitivity.In the drug release performance test,doxorubicin was used as the drug and the dynamic dialys is method at different time points in vitro release was taken advantage of to evaluate the different carrier drug release properties of chitosan and composites.The sustained release of 3 kDa CS-rGO in the composites was the best,and the sustained release performance of 200 kDa CS was increased the most.2.Preparation,Characterization and Properties of Chitosan Ionic Liquid DerivativesGraphene CompositeIn this section,bromide-linked chitosan ionic liquid derivatives(CILC)were prepared by imidazole ionic liquid and chitosan,and then CILC was used to modify graphene to obtain chitosan ionic liquid derivative-graphene composite(CILC-rGO).The obtained composites were characterized by FT-IR,TG,UV,XRD and so on.FTIR and UV characterization confirmed that the oxide graphene was reduced during the reaction and the original functional groups of CILC were retained in the composites.The content of rGO in the composites was also calculated by TG characterization.When the length of the alkyl chain of the chitosan derivative was changed,the water absorption capacity and the state after water absorption of CILC were differe nt,which were aqueous solution or hydrogel state respectively.However,the CILC-rGO had good dispersibility in water.In the case of the same carbon chain length,the dispersibility of the CILC in different DS was different and the dispersion at extrem of 48% 1,6-CILC-rGO is greater.The drug release property of each sample was also investigated.3.Preparation,Characterization and Dispersion Property of Noncovalent Carbazolebased Conjugated Polymer-Graphene CompositesIn this chapter,three carbazole-based conjugated polymers(P1,P2,P3)with different structural units were designed and obtained.The three products P1-rGO,P2-rGO and P3-rGO were prepared by non-covalent modification of graphene.The resulting material was characterized by a variety of methods.The characterization of TG could judge the modified ability of polymer with the different spacer groups by the percentage of rGO in P-rGO.The UV-vis absorption spectra showed that the dispersibility of P1-rGO in tetrahydrofuran was excel ent,which is consistent with Lambert-Beer's law.Through the TEM,the morphology of graphene on the polymer surface could be observed,which was different due to the various apacer groups.The dispersion effect of the three composites varied widely due to the spacing of the three polymers with different sizes.The dispersion of P1-rGO was the best,and it could be dispersed into THF,DMF and DMSO at 1.5 mg/mL,which indicated that the combination of graphene and P1 containing tetrasthenylvinyl groups was stronger than the other two conjugated polymers.This was not only related to its large ? conjugatio n system,but also with the larger steric hindrance produced by its distorted configurat io n.Through the limitation of the polymer structure,the composites with different graphene content could be obtained,which provided a new idea for the preparation of graphene composites.4.Preparation,Characterization and Dispersion Property of Conjugated Carbazole Polymer Covalent Graphite CompositesIn this section,three kinds of carbazole polymers(P1,P2,P3)were covalent ly modified with graphene after the nucleophilic reaction,and the nitrogen anion was generated through the activation of NH in the carbazole moiety by NaH.The composites were characterized by IR,FT-IR,UV-Vis,XRD,TG,FE-SEM and TEM.The results demonstrated that the carbazole-based conjugated polymer was bonded to the graphene layers by C-N bond and the polymer was wrapped by the graphene,which was thin as the gauze and had obvious wrinkles.Because of the introduction of graphene,the original fluorescence of polymer was quenched.The content of graphene in the composites was different.The three composites all had good dispersibility in tetrahydrofuran.