Characterization of Conformation and Locations of C–F Bonds in Graphene Derivative by Polarized ATR-FTIR

It is still a challenge to explore the orientation and location of chemical groups in the two-dimensional derivative of graphene. In this study, polarized attenuated total reflectance Fourier transform infrared spectroscopy (polarized ATR-FTIR) was employed to investigate the orientation and location of C–F groups in the corresponding graphene derivative sheets, which facilitates building a relationship between the bonding nature and fine structure. There were two types of C–F bonding, (C–F)_I and (C–F)_II, in fluorinated graphene sheets. It was found that (C–F)_II bonds were linked at the coplanar carbon atoms in the weakly fluorinated region (C_<i>x</i>F, <i>x</i> ≥ 2), whereas the (C–F)_I bonds cluster at the strongly deformed carbon framework with a F/C ratio of about 1. The thermostability of (C–F)_II is lower than that of (C–F)_I bonds. This is because the coplanar structure of the weakly fluorinated region tends to transform to the planar aromatic ring with the breaking of the C–F bond as compared with the strong fluorinated nonplanar region

Fluorographene with High Fluorine/Carbon Ratio: A Nanofiller for Preparing Low‑κ Polyimide Hybrid Films

Sufficient amounts of fluorographene sheets with different sheet-size and fluorine/carbon ratio were synthesized for preparing of fluorographene/polyimide hybrids in order to explore the effect of fluorographene on the dielectric properties of hybrid materials. It is found that the fluorine/carbon ratio, width of band gap, and sheet-size of fluorographene play the important roles in determining the final dielectric properties of hybrids. The fluorographene with high fluorine/carbon ratio (F/C ≈ 1) presents broaden band gap, enhanced hydrophobicity, good dispersity and thermal stability, etc. Even at a very low filling, only 1 wt %, its polyimide hybrids exhibited drastically reduced dielectric constants as low as 2.1 without sacrificing thermal stability, improved mechanical properties obviously and decreased water absorption by about 120% to 1.0 wt %. This provides a novel route for improving the dielectric properties of materials and a new thought to carry out the application of fluorographene as an advanced material

One-Step Preparation of Oxygen/Fluorine Dual Functional MWCNTs with Good Water Dispersibility by the Initiation of Fluorine Gas

It is still a challenge to prepare water-dispersible carbon nanotubes which are proved to have great potential in numerous applications. In this present work, as low as 2% fluorine gas was used as initiator to prepare oxygen/fluorine dual functional MWCNTs (OF-MWCNTs) with good water dispersibility through a one-step method under oxygen atmosphere. The aromatic structure of OF-MWCNTs is reserved to some extent resulting in better electrical conductivity than pure fluorinated MWCNTs (F-MWCNTs). The amount of oxygen atoms and fluorine atoms (hereinafter referred to as “O-content” and “F-content”) of OF-MWCNTs is up to 8.8% and 7.5%. Fourier transform infrared spectroscopy (FTIR) manifests that - COOH is covalently bonded onto the surface of OF-MWCNTs. In addition, the OF-MWCNTs sample is pH-sensitive, which further validates the successful introduction of -COOH. The successful covalent attachment of -COOH onto MWCNTs dramatically improves the hydrophilia of MWCNTs which always present hydrophobic character. It is deduced that fluorine creates reactive sites for oxygen, increases the oxygen content, and eventually results in the dispersibility of OF-MWCNTs in water. The corresponding hydrophilic OF-MWCNTs film shows good performance for separating oil-in-water emulsions. Meanwhile, the good dispersibility of OF-MWCNTs in organic solvents also makes it possible to be applied in various composites