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...

/pdf/graphene-polymer-nanocomposites-19884oy559.pdf

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

Effect of polar modifications on cure characteristics, solvent resistance and thermo-mechanical properties of metallocene-based polyolefinic elastomers

Being nonpolar in nature, butyl rubber (IIR) has poor compatibility toward polar polymers and fillers. It can be improved by grafting polar substrates on the butyl elastomer. Radiation-induced polymer processing is getting increasing interest, as it leads to new and improved polymers with desirable and interesting properties. In this investigation, electron beam radiation has been used to graft methyl methacrylate (MMA) and butyl acrylate (BA) on IIR. This process has several advantages over conventional grafting processes such as cationic polymerization (which needs very low temperature and stringent reaction conditions) and solution radical polymerization (which often needs solvent removal and recycling). The grafted polymers were characterized by using 1H NMR, IR, TGA, and SEM analysis. The degree of grafting increases with a decrease in irradiation dose as well as with an increase in monomer concentration. It was observed that there was a decrease in intrinsic viscosity in irradiated IIR samples, indicating the chain scission. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1340–1346, 2006

Grafting of butyl acrylate and methyl methacrylate on butyl rubber using electron beam radiation

Room temperature ionic liquids (RTILs) have proved over recent years to be useful and unique reaction media for a variety of chemical reactions. Faster reaction rates and better selectivities are often observed in RTILs as compared to those in common organic solvents. In addition to these advantages, the low volatility, nonflammability, and recycling potential also help RTILs become a preferred alternative reaction medium to meet environmental and other requirements. This is evidenced by the ever increasing number of papers published in this area every year and interesting and important discoveries. When conventional free radical polymerizations are carried out in RTILs, there is an increase in the propagation rate due to the high polarity of the RTIL and a decrease in the termination rate because of the high viscosity of the RTILs, and thus the overall reaction rate is greatly increased along with an increase in molecular weight. For living/controlled polymerization such as atom transfer radical polymerization and radical addition-fragmentation and transfer, the reactions in RTILs are still controllable with faster reaction rates and easy separation of catalysts and/or ligands from the resulting polymers. Nearly all types of polymerization processes have now been successfully conducted in RTILs, often with advantageous effects.


Keywords:

ionic liquid;
polymerization

Polymerization in Ionic Liquids

A new class of ionomer was developed through the grafting of acrylic acid onto a metallocene-based poly(ethylene octene) elastomer, followed by its neutralization with zinc acetate. The ionomeric product was characterized through Fourier transform infrared spectroscopy, small-angle X-ray scattering, and transmission electron microscopy studies. The effect of the crystallinity and pendent chain length on the ionomeric modification was also studied through the variation of the level and nature of comonomer, respectively. The impact of these ionomeric modifications on various physicomechanical properties was thoroughly investigated with differential scanning calorimetry and mechanical, dynamic mechanical, and thermogravimetric analysis, and the resulting properties were correlated with the structure of the modified elastomers. The ionomerization of the base elastomers caused a significant improvement in the mechanical and thermal properties compared to the corresponding pristine elastomer. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Ionomeric Modification of a Metallocene-Based Polyolefinic Elastomer and Its Influence on the Physicomechanical Properties: Effects of the Crystallinity and Pendent Chain Length

Elastomers and their composites are extensively used as a thermal insulation system in heat treatment, power generation, fire protection, and aerospace. Among different elastomers, low-density ethylene propylene diene terpolymer (EPDM) has interesting properties, such as excellent resistance to aging and oxidative degradation due to its saturated back bone. Furthermore, introduction of polyimide (PI) to the base elastomer increases its thermal stability. On the other hand, carbon nanofiber (CNF) reinforces the matrix to enhance the mechanical properties with an additional advantage of better char yield. To achieve better rubber-filler compatibilization, modification of EPDM was carried out by grafting with maleic anhydride (MAH). Morphological studies by scanning electron microscopy and high-resolution transmission electron microscopy exhibited uniform dispersion of nanofillers throughout MAH grafted EPDM matrix. Thermal properties of the EPDM/PI nanocomposites were characterized by thermogravime...

Nikhil K. Singha

Papers

Effect of polar modifications on cure characteristics, solvent resistance and thermo-mechanical properties of metallocene-based polyolefinic elastomers

Grafting of butyl acrylate and methyl methacrylate on butyl rubber using electron beam radiation

Polymerization in Ionic Liquids

Ionomeric Modification of a Metallocene-Based Polyolefinic Elastomer and Its Influence on the Physicomechanical Properties: Effects of the Crystallinity and Pendent Chain Length

Carbon nanofiber composite with epdm and polyimide for high-temperature insulation