Preparation And Unique Properties Of Flowable Graphene

Since graphene and nanoparticle fluids have been prepared in 2004 and 2005, On the basis of consulting plenty of references on the graphene, inorganic nanoparticles with liquid-like behavior and other related literature, we prepared graphite oxide by two different methods:mixed acid method and Hummers method, we finally selected Hummers method after comparing them. 3-(trihydroxysily)-1-propanesulfonic acid (SIT) was grafted onto the surface of graphene oxide, then it is neutralized by NaOH to prepare graphene organic ion salt; finally, The cationic quaternary ammonium salt with PEG chain (NPEQ) was used for ion exchange with the graphene organic ion salts. As a result, a new type of flowable graphene was.prepared.Both mixed acid method and Hummers method could impove their dispersion in water. X-ray Diffraction (XRD) and Atomic force microscopy (AFM) were used to compare the two types of oxide methods. We could not see graphene in AFM. The crystal structure of graphite could not be changed by ultrasounding in mixed acid. On the contrary, it's crystal structure could be destroyed by Hummers method. And we can see graphene with the thickness of lnm in AFM. Meanwhile, Fourier-transform Infrared spectroscopy (FTIR), Raman spectroscopy(Raman), Transmission Electron Microscopy (TEM), Scanning Electron Microscopy(SEM) were used to characterize it. We could see it's peeling off in SEM.To prepare graphene organic ion salt, SIT was grafted onto the surface of graphene oxide, then we neutralized it by NaOH; The FTIR results domonstrated that SIT was covalently grafted onto the surface of graphene oxide; UV-vis absorption spectra showed that NaOH can partially reduce graphene oxide. TG curvess showed that the organic content of the graphene decreased after neutralizing by NaOH; it was consistent with the result of UV-vis absorption spectra due to the removal of oxygen functional groups by NaOH. AFM result showed that the thickness of graphene slightly increased after grafted by SIT, which was related to the dehydration condensation of-OH on graphene layers and Si-OH in SIT, it caused cross-linking between different layers of graphene.Flowable graphene was synthesized by ion exchange between graphene organic ion salt and cationic quaternary ammonium salt with PEG chain (NPEQ), it could flow at room temperature. Flowable graphene was characterized by FTIR, TG, Differential scanning calorimetry thermal(DSC) and TEM. DSC domonstrated that the flowable graphene behaviors liquid with a low melting temperature of 0.709℃. Simultaneously, TG showed that the organic content was as high as 89%and the structure of graphene flakes was maintained in the process of ion exchange.