This review aims at updating various studies to design BaTiO 3 @polymer/Fluoropolymer nanocomposites, to study their properties and performances and to supply their applications. Dielectric nanocomposite materials with high energy density exhibit promising performances for energy storage applications.Major efforts have been performed to combine the efficient properties and high dielectric constant of ceramics with the flexibility and easy processing of polymers.Actually, the dielectric properties of the nanocomposite are influenced by the dielectric features of both ceramic and polymer. Thus, the choice of the two components become crucial in turning the desired properties. Another important factor is the modification strategy to get such nanocomposites, where the major routes are the "grafting from", "grafting onto" and melt process while most fluoropolymers studied are polyvinylidene fluoride (PVDF), VDF containing-copolymers and terpolymers and poly(acrylates)bearing fluoroalkyl side groups. Additionally, fluorinated silanes have also been involved in sol-gel chemistry to decorate BaTiO 3 surface, as well as tetrafluorophthalic acid or fluorinated dopamine did. This review also summaries the current state of high energy density nanocomposites based on BaTiO 3 as a ceramic nanofiller and fluoropolymer as matrix.

To accompany the search for optimal materials in electrochemical supercapacitors, appropriate characterization tools to assess key parameters of newly developed electrodes are required. Here we demonstrate the capabilities of ac-mode electrogravimetry to study in details the capacitive charge storage mechanisms in electrochemically reduced graphene oxide (ERGO) thin film electrodes. The coupling of electrochemical impedance spectroscopy (EIS) with fast quartz crystal microbalance (QCM) complements classical electrochemical quartz crystal microbalance (EQCM) by capturing here the dynamics of the electroadsorption process, identifying charged moieties and detecting solvation effects. We evidenced the coelectroadsorption of two types of cationic species (fully and partially hydrated cations) in the potential range studied and the indirect intervention of free solvent molecules. Further kinetic information on electroadsorption is also obtained which leads to a full deconvolution of the global EQCM response at both gravimetric and temporal level. Through a fine analysis of the interactions of different cations of period one elements, Li + , Na + , and K + , with ERGO, we evidenced the critical role of solvation processes on the kinetics of electroadsorption, and provided an experimental proof to the phenomena that smaller ions are more tightly bound to their water molecules such that an inverse relationship exists between the dehydration energy and the ion size. Such gravimetric and dynamic subtleties are unreachable with classical tools and with EQCM method alone which permits us to suggest the ac-mode electrogravimetry as a baseline diagnostic tool to explore charge transfer mechanisms at the nanoscale.

This work aims to study how the magnitude, frequency, and duration of an AC electric field affect the orientation of two kinds of nanofibrillated cellulose (NFC) dispersed in silicone oil that differ by their surface charge density and aspect ratio. In both cases, the electric field alignment occurs in two steps: first, the NFC makes a gyratory motion oriented by the electric field; second, NFC interacts with itself to form chains parallel to the electric field lines. It was also observed that NFC chains become thicker and longer when the duration of application of the electric field is increased. In-situ dielectric properties have shown that the dielectric constant of the medium increases in comparison to the randomly dispersed NFC (when no electric field is applied). The optimal parameters of alignment were found to be 5000 Vpp/mm and 10 kHz for a duration of 20 min for both kinds of NFC. The highest increase in dielectric constant was achieved with NFC oxidized for 5 min (NFC-O-5 min) at the optimum conditions mentioned above.

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Short date palm tree lignocellulosic fibers have been used as a reinforcing phase in commodity thermoplastic matrices [poly(propylene) and low density polyethylene]. Compatibilization of the fibers was carried out with the use of maleic anhydride copolymers. The morphology, thermal and mechanical properties of the resulting composites were characterized using SEM, DSC and tensile tests. The reinforcing capability of the unmodified fibers was found to depend on the nature of the matrix and the main parameter governing the composite behavior was the degree of crystallinity of the matrix. Compatibilization was reported to enhance the mechanical performances for both sets of composites up to a critical amount of compatibilizer beyond which the degree of crystallinity of the matrix decreases.magnified image

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The synthesis and the characterization of original copolymers based on vinylidene cyanide (VCN) and 1H,1H,2H,2H-perfluorodecyl vinyl ether (FAVE8) are presented. While VCN is known to be very reactive in radical homopolymerization in contrast to the vinyl ether which does not homopolymerize, the radical copolymerization of VCN with FAVE8 unexpectedly led to alternating poly(VCN-alt-FAVE8) copolymers. Seven radical copolymerization reactions were investigated with [VCN] 0 /[FAVE8] 0 percent molar ratios ranging between 15/85 and 80/20. The copolymer compositions of these copolymers were assessed by elemental analyses and showed 32 mol. % (in one case only) to 56 mol. % of VCN (ca. 50 mol % in most cases). From the monomer -polymer copolymerization curve, the Fineman-Ross and Kelen-Tüdos laws enabled to assess the reactivity ratios (r VCN = r 12 = 0.08 ± 0.01; r FAVE8 = r 21 = 0.07 ± 0.01 at 75 °C) while the Revised Patterns Scheme led to r 12 = 2.7 x 10 -3 and r 21 = 4.0 x 10 -6 suggesting an alternating tendency of that radical copolymerization. Thermogravimetric analysis of these copolymers showed exceptional thermal stability, the