Quasi all water soluble composites use graphene oxide (GO) or reduced graphene oxide (rGO) as graphene based additives despite the long and harsh conditions required for their preparation. Herein, polyvinyl alcohol (PVA) films containing few layer graphene (FLG) are prepared by the co-mixing of aqueous colloids and casting, where the FLG colloid is first obtained via an efficient, rapid, simple, and bio-compatible exfoliation method providing access to relatively large FLG flakes. The enhanced mechanical, electrical conductivity, and O2 barrier properties of the films are investigated and discussed together with the structure of the films. In four different series of the composites, the best Young’s modulus is measured for the films containing around 1% of FLG. The most significant enhancement is obtained for the series with the largest FLG sheets contrary to the elongation at break which is well improved for the series with the lowest FLG sheets. Relatively high one-side electrical conductivity and low percolation threshold are achieved when compared to GO/rGO composites (almost 10−3 S/cm for 3% of FLG and transport at 0.5% FLG), while the conductivity is affected by the formation of a macroscopic branched FLG network. The composites demonstrate a reduction of O2 transmission rate up to 60%.
Here is presented the elaboration of Few Layer Graphene/TiO 2 photocatalytic composites (FLG/TiO 2 ) with FLG loadings from 0.5 to 11 wt.%. Contrary to commonly used (reduced) graphene oxide obtained by long and harsh conditions synthesis, FLG was synthesized by simple, fast, efficient and eco-friendly exfoliation method. The enhancement of defective/functionalized sites density for attachment of TiO 2 species was achieved via calcination process at 450 °C. The nanocomposites were evaluated toward H 2 production from methanol under artificial solar light irradiation, without the use of a co-catalyst. It was observed that the best activities are provided by the composites with the lowest loading: 0.5 and 1.0 wt.% FLG/TiO 2 that are 2-3 times more efficient than reference and commercial TiO 2 . The photocatalytic activity of the composites was correlated to their surface area, morphological, structural, optical properties and kinetics of free electron mobility properties. The enhanced activity is attributed to higher surface area, better photogenerated charges separation thanks to electrons' delocalization and trapping onto graphene layers well interfaced with TiO 2 nanoparticles, but also to additional FLG visible light absorption properties and charge carriers' generation. The impact of enhanced FLG edges defects/functionalities is reflected as well via selected analysis and hydrogen generation.
Four series of polylactide (PLA) based composite films containing horizontally aligned few layer graphene (FLG) flakes of high aspect ratio and adsorbed albumin are prepared. The mechanical and thermal properties varies with percentage, dispersion degree and size of FLG flakes. Great improvement up to 290% and 360% of tensile modulus and strength respectively were obtained for the composite containing high lateral size of FLG at 0.17% wt, and up to 60% and 80% for the composite with very well dispersed 0.02% wt FLG. The composites of PLA and PEG‐PLLA containing very well dispersed FLG flakes at 0.07% wt are ductile showing enhancement of elongation at break up to respectively 80% and 88%. Relatively high electrical conductivity, 5 × 10−3 S/cm, is measured for PLA film charged with 3% of FLG.
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