Preparation Of Graphene Functional Modification And Its Polyurethane Nanocomposites

The two functionalization modified graphene were prepared with imidazolium ionicliquid1-allyl-methylimidazolium chloride (AmimCl) and3-aminopropyltriethoxysilane(KH-550) respectively, studying their dispersibility in N, N-dimethylformamide (DMF) andbutyl acetate organic solvents. The functionalization modified graphene based polyurethane(PU) nanocomposites was fabricated by means of solution blend and in situ composite, andmicrostructure, compasibility, mechanical and thermodynamics properties of compositeswere researched in further.Ionic liquid non-covalent modified graphene (IL-G) was prepared in one-step by treatinggraphene oxide (GO) with AmimCl and hydrazine hydrate simultaneously. Fourier transforminfrared spectroscopy (FTIR), Ultraviolet-visible spectroscopy (UV-vis), atomic forcemicroscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were performed tocharacterize the structure and dispersibility of IL-G nanosheets. Investigation resultsdemonstrated that the π-π and cation-π interaction between IL-G and graphene made IL-Gstrong attaching to surface of graphene and will be not washed off. At the same time, IL-Gshowed excellent dispersibility and can be stably dispersed in DMF and butyl acetate. Themaximum dispersibility concentration of IL-G in DMF and butyl acetate is1.69mg/mL and1.12mg/mL respectively.IL-G/Polyurethane nanocomposites was prepared by solution blend. Scanning electronmicroscope (SEM) was used to observe fracture morphology of composites. The resultsdisplayed that IL-G nanosheets, with fold morphology, was homogeneous dispersion inpolyurthane matrix and no aggregation. Meanwhile, the obscure interface between IL-Gnanosheets and polyurethane resin was also observed, which implied that IL-G nanosheetshad a good compatibility with in PU matrix caused by interfacial interaction between PUchains and IL-G nanosheets. The mechanical and thermodynamic properties of compositehave a larger degree improvement along with increase of IL-G contents. With the addition of0.608wt.%IL-G, the tensile strength and therml conductivity of composite respectivelyincrease by68.5%and34%in comparison with that of neat PU, a nd therma l stabilitytemperature of5%weight loss was enhanced approximately40oC, indicating efficiently improvements properties of PU composites with a small amount of IL-G nanosheets.In order to further improve compatibility between graphene and PU resin, KH-550functionalized graphene (KHG) was prepared by reacting GO with3-aminopropyltriethoxysilane and simultaneously reduced by hydrazine hydrate.Subsequently, KHG/polyurethane nanocomposites were fabricated via in situ composite. Thereactive groups was introduced to KHG surface and can react with isocyanate group toproduce chemical interaction, showing a good compatibility. Thermogravmetric analysis,X-ray diffraction, electronic tensile test and differential scanning calorimeter were used tocharacterize PU composites properties. Analysis results showed that thermal stabilitytemperature is approximately50°C higher than that of the neat PU at the KHG loadings of0.2wt.%. Meanwhile, the tensile strength and thermal conductivity of the KHG/PUnanocomposite also increase by227%and40%, respectively.