Carbon nanotube–polymer composites: Chemistry, processing, mechanical and electrical properties

Fundamentals, processes and applications of high-permittivity polymer–matrix composites

Study of flexible nanodielectric materials (FNDMs) with high permittivity is one of the most active academic research areas in advanced functional materials. FNDMs with excellent dielectric properties are demonstrated to show great promise as energy-storage dielectric layers in high-performance capacitors. These materials, in common, consist of nanoscale particles dispersed into a flexible polymer matrix so that both the physical/chemical characteristics of the nanoparticles and the interaction between the nanoparticles and the polymers have crucial effects on the microstructures and final properties. This review first outlines the crucial issues in the nanodielectric field and then focuses on recent remarkable research developments in the fabrication of FNDMs with special constitutents, molecular structures, and microstructures. Possible reasons for several persistent issues are analyzed and the general strategies to realize FNDMs with excellent integral properties are summarized. The review further highlights some exciting examples of these FNDMs for power-energy-storage applications.

Flexible Nanodielectric Materials with High Permittivity for Power Energy Storage

A review on the mechanical and electrical properties of graphite and modified graphite reinforced polymer composites

Temperature dependent microwave attenuation behavior for carbon-nanotube/silica composites

Giant Dielectric Permittivities in Functionalized Carbon-Nanotube/ Electroactive-Polymer Nanocomposites†

Rescaled temperature dependence of dielectric behavior of ferroelectric polyvinylidene fluoride (PVDF) filled with electroactive ceramic particles of rocksalt-type Li and Ti codoped NiO (LTNO) was studied at wide frequency ranges. Dielectric behavior of the flexible PVDF-LTNO composites with LTNO filler at the volumetric function of 0.3 exhibits a dielectric constant value, e≈50 at broad temperature range (290–360 K), and the value is frequency independent from 103 to 106Hz. The dielectric response of the composite is almost in accordance to that of pure PVDF matrix polymer. It was found that though the dielectric constant value of the composites is high due to an introduction of the rock salt-type LTNO ceramic particles with high dielectric constant, the glass transition of the polymer and dielectric relaxation related to the wide-angle oscillation of polar groups attached to the main polymer chain determine the dielectric behavior of the composite.

Rescaled temperature dependence of dielectric behavior of ferroelectric polymer composites

It is reported that low volatile solvent could slow down the rate of solvent volatilization during the electrospinning process and hydrophobic biomaterials were easily to form branching fiber, which would be used as a potential biomaterial as wound dressing because of its bacterial barrier property. In this work, silver ion (Ag+) was used as the anti-bacterial components to explore the effect of N, N-dimethylformamide (DMF) as a fiber differentiation inducer on hydrophilic materials-Polyvinyl alcohol (PVA), Polyvinylpyrrolidone (PVP) and Eudragit L-100 during the electrospinning. The results of scanning electron microscopy (SEM) and X-ray diffraction (XRD) confirmed that DMF could reduce the diameter of electrospun fibers and increased crystallinity of the electrospun fibers. The results of water absorption test, X-ray photoelectron spectroscopy (XPS) and in vitro antibacterial activity showed that comparing with cotton non-woven fabric, gauze and cotton, the fiber with strong water absorption could load more silver ions and had stronger inhibitory properties against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli). CCK-8 assay showed that the cytotoxicity of DMF induced hydrophilic material electrospun fibers and their silver loaded electrospun fibers were all above 90%, which suggested that the fibers could be developed for clinical application. This work could provide an opportunity for improving the properties of electrospun fibers which have potential to be applied as wound dressings. 

Lan Wang

Papers

Giant Dielectric Permittivities in Functionalized Carbon-Nanotube/ Electroactive-Polymer Nanocomposites†

Rescaled temperature dependence of dielectric behavior of ferroelectric polymer composites

Effects of solvents on electrospun fibers and the biological application of different hydrophilic electrospun mats