3 research outputs found
Fluorographene with High Fluorine/Carbon Ratio: A Nanofiller for Preparing LowâÎș 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 â
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
High-Yield Production of Highly Fluorinated Graphene by Direct Heating Fluorination of Graphene-oxide
By
employing honeycomb GO with large surface area as the starting
materials and using elemental fluorine, we developed a novel, straightforward
topotactic route toward highly fluorinated graphene in really large
quantities at low temperature. The value of F/C molar ratio approaches
to 1.02. Few-layer fluorinated graphene sheets are obtained, among
which the yield of monolayered FG sheet is about 10% and the number
of layers is mainly in the range of 2â5. Variations in morphology
and chemical structure of fluorinated graphene were explored, and
some physical properties were reported
Preparing Highly Fluorinated Multiwall Carbon Nanotube by Direct Heating-Fluorination during the Elimination of Oxygen-Related Groups
Pristine
and oxidized multiwalled carbon nanotubes (MWCNTs) were separately
prepared and directly fluorinated with F<sub>2</sub> through two different
routes: heating-fluorination and isothermal-fluorination. The amount
of fluorine atoms (hereinafter referred to as âF-contentâ)
bonding to the fluorinated samples was largely dependent on the modifing
route and chemical bonding of MWCNTs. The F-content of heating-fluorinated
pristine and oxidized MWCNTs was 3.2% and 9.2% respectively, which
were about 8 times and 18 times that of the corresponding isothermal-fluorinated
MWCNTs. According to structural analysis of samples before and after
fluorination, it was found that thermal elimination of oxygen-related
groups bonding to MWCNTs contributed to the formation of strongly
covalent CâF bonds during heating-fluorination. It was considered
that the oxygen-related groups provided reactive sites for the fluorination.
The fluorination reaction took place at an sp<sup>3</sup> carbon linking
with the oxygen-related groups and did not increase the density of
defect on MWCNTs. A radical-mediated mechanism is accepted for this
reaction. Thus, MWCNTs could be first oxidized to increase the number
of oxygen-related groups and then heating-fluorinated by F<sub>2</sub> directly to get highly fluorinated MWCNTs with stable CâF
bonds