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A novel hydroxyl-containing polyimide film has been designed and fabricated as a chemosensor for the real-time visualization of F− with high selectivity and sensitivity.

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As a new graphene derivative, graphene fluoroxide (GFO) has not been fully studied because of its complex preparation process. In this paper, two simple methods, a modified Hummers' method and an improved method, were adopted to oxidize unsaturated commercial graphite fluoride (GIF) to prepare graphite fluoroxide (GIFO), the precursor of GFO. GFO was finally obtained via liquid-phase ultrasonic exfoliation of GIFO in organic solvents. Multiple spectroscopic techniques were used to characterize GIFO and GFO.The test results indicate that both of the two methods can covalently bond oxygen functional groups to graphene fluoride (GF) sheets successfully, but the modified Hummers' method gives higher yield and oxidizability. The structure of the GFO sheet is confirmed as few-layer by its atomic force microscopy results and transmission electron microscopy images. UV-vis and fluorescence emission measurements suggest that introducing oxygen groups into GF sheets can change their optoelectronic properties.Based on this, GFO with tunable optoelectronic properties might be facilely obtained in large batches through oxidization and liquid-phase exfoliation of unsaturated GIF with different fluorine coverage.

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A new approach to synthesize fluorine-containing graphene oxide (FCGO) was proposed, in which a less toxic reagent was used rather than fluorine gas or anhydrous hydrogen fluoride. The dielectric and mechanical properties of polyimide composites were improved by incorporating a small amount of FCGO. FCGO served as not only nanofiller to lower the dielectric constant of PI films but also inorganic toughening particles to improve the toughness of PI films. The dielectric constant of PI films with 0.6 wt % FCGO was decreased from 3.33 for pure PI to 2.34. In addition, both the tensile strength and Young's modulus of PI films with 0.6 wt % FCGO were increased to 141 MPa and 4.95 GPa from 118 MPa and 2.81 GPa for pure PI, respectively. In addition, its tensile energy to break was enhanced to 31.6 MJ/m 3 from 20.8 MJ/m 3 .