Recent advances in graphene based polymer composites

Graphene has emerged as a subject of enormous scientific interest due to its exceptional electron transport, mechanical properties, and high surface area. When incorporated appropriately, these atomically thin carbon sheets can significantly improve physical properties of host polymers at extremely small loading. We first review production routes to exfoliated graphite with an emphasis on top-down strategies starting from graphite oxide, including advantages and disadvantages of each method. Then solvent- and melt-based strategies to disperse chemically or thermally reduced graphene oxide in polymers are discussed. Analytical techniques for characterizing particle dimensions, surface characteristics, and dispersion in matrix polymers are also introduced. We summarize electrical, thermal, mechanical, and gas barrier properties of the graphene/polymer nanocomposites. We conclude this review listing current challenges associated with processing and scalability of graphene composites and future perspectives f...

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Graphene/Polymer Nanocomposites

Composite films of chemically converted graphene (CCG) and polyaniline nanofibers (PANI-NFs) were prepared by vacuum filtration the mixed dispersions of both components. The composite film has a layered structure, and PANI-NFs are sandwiched between CCG layers. Furthermore, it is mechanically stable and has a high flexibility; thus, it can be bent into large angles or be shaped into various desired structures. The conductivity of the composite film containing 44% CCG (5.5 × 102 S m−1) is about 10 times that of a PANI-NF film. Supercapacitor devices based on this conductive flexible composite film showed large electrochemical capacitance (210 F g−1) at a discharge rate of 0.3 A g−1. They also exhibited greatly improved electrochemical stability and rate performances.

Supercapacitors Based on Flexible Graphene/Polyaniline Nanofiber Composite Films

Progress in preparation, processing and applications of polyaniline

Keywords: Fragmentation Chain-Transfer ; Self-Assembled Monolayers ; Walled Carbon Nanotubes ; Well-Defined Polymer ; Nitroxide-Mediated Polymerization ; Block-Copolymer Brushes ; Poly(Methyl Methacrylate) Brushes ; Transfer Raft Polymerization ; Quartz-Crystal Microbalance ; Poly(Acrylic Acid) Brushes Reference EPFL-REVIEW-148464doi:10.1021/cr900045aView record in Web of Science Record created on 2010-04-23, modified on 2017-05-10

Polymer Brushes via Surface-Initiated Controlled Radical Polymerization: Synthesis, Characterization, Properties, and Applications

Density is an important parameter that influences the properties and performances of rigid polyurethane foam (PUF). Rigid PUF with different densities were prepared by varying the amount of distilled water as blowing agent. This investigation reports the mechanical, morphological, water absorption, thermal conductivity, and thermal behavior of rigid PUF varying with the density, which controls the foam architecture. The density of the PUF decreased from 116 to 42 kg/m3 with an increase in the amount of water from 0.1 to 3.0 parts per hundred polyol by weight (phr), respectively. It was found that the mechanical properties of the PUFs changed with the foam density. The results of water absorption of the PUFs showed that water absorption increased with decrease in density, due to increase in the cell size and decrease in the cell-wall thickness. The thermal conductivity measurements showed that the thermal conductivity decreased with increase in density. It was due to the decrease in cell size. The thermal analysis of the PUFs shows that the glass transition temperature increases with the decrease in foam density, but the thermal stability decreases with the decrease in foam density. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Effect of foam density on the properties of water blown rigid polyurethane foam

This investigation reports the effective use of the Diels−Alder (DA) reaction, a “click reaction” in the preparation of thermally amendable and self-healing polymeric materials having reactive furfuryl functionality. In this case, the DA and retro-DA (rDA) reactions were carried out between the tailor-made homo- and copolymer of furfuryl methacrylate prepared by atom-transfer radical polymerization and a bismaleimide (BM). The kinetic studies of DA and rDA reactions were carried out using Fourier transform infrared spectroscopy. The DA polymers were insoluble in toluene at room temperature. When the DA polymers were heated at 100 °C in toluene, it was soluble. This is because of the cleavage between furfuryl functionality and BM. The chemical cross-link density was determined by the Flory−Rehner equation. The cross-linked polymer showed much greater adhesive strength at room temperature, but the adhesive strength was quite low at higher temperature. The self-healing capability was studied by using scannin...

“Click Chemistry” in Tailor-Made Polymethacrylates Bearing Reactive Furfuryl Functionality: A New Class of Self-Healing Polymeric Material

Halogen-free flame retardant PUF: Effect of melamine compounds on mechanical, thermal and flame retardant properties

The synthesis of polyaniline (PAni) powder was carried out from 0.15M of aniline and 1M of HCl in distilled water at room temperature in a single compartment electrochemical cell. The PAni was again synthesized chemically keeping the composition and temperature same as electrochemical process but adding equimolar amount of ammonium peroxydisulfate as an oxidizing agent. Then the PAni obtained from these two methods were characterized by the conductivity, solubility, X-ray, FTIR, TGA, UV, and SEM, and compared. Result shows that the electrochemically synthesized PAni (ECS-PAni) has somewhat lower conductivity, higher solubility, more benzenoid rings than quinoid rings, lower crystallinity, higher band energy, and higher particle size than that of chemically synthesized PAni (CS-PAni). © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 1900–1904, 2007

Nikhil K. Singha

Papers

Progress in preparation, processing and applications of polyaniline

Effect of foam density on the properties of water blown rigid polyurethane foam

“Click Chemistry” in Tailor-Made Polymethacrylates Bearing Reactive Furfuryl Functionality: A New Class of Self-Healing Polymeric Material

Halogen-free flame retardant PUF: Effect of melamine compounds on mechanical, thermal and flame retardant properties

Electrochemical synthesis of polyaniline and its comparison with chemically synthesized polyaniline