Metallic single-walled carbon nanotubes for conductive nanocomposites

This article reports an unambiguous demonstration that bulk-separated metallic single-walled carbon nanotubes offer superior performance (consistently and substantially better than the as-produced nanotube sample) in conductive composites with poly(3-hexylthiophene) and also in transparent conductive coatings based on PEDOT:PSS. The results serve as a validation on the widely held view that the carbon nanotubes are competitive in various technologies currently dominated by conductive inorganic materials (such as indium tin oxide).     

Development of conductive bacterial cellulose foams using acoustic cavitation

Bacterial cellulose (BC) has found applications in various fields ranging from healthcare to electronics. Functionalization of cellulose to impart conductive properties has been met with challenges due to superficial coating rather than uniform interactions with the conducting polymers. In this work, mechanical disruption is shown to be a facile strategy to develop BC-PEDOT:PSS conductive foams without the use of any harsh chemical treatments to functionalize cellulose. The strategy allows for uniform polymer intercalation with the cellulose nanofibers imparting superior conductive properties to the functional material. The conductive foams with low PEDOT:PSS ratio exhibit conductivity of 0.7 S/cm and are cytocompatible with human dermal fibroblasts (HDFa) cells.

     

Electrically conductive transparent papers using multiwalled carbon nanotubes

We describe a novel class of electrically conductive transparent materials based on multiwalled carbon nanotubes (MWCNTs). Transparent nanocomposites were fabricated by incorporating an aqueous silk fibroin solution into bacterial cellulose membranes. The transparent nanocomposites had a high transmittance in the visible and infrared regions, regardless of the bacterial cellulose fiber content, due to the nanosize effect of the bacterial cellulose nanofibrils. This phenomenon allowed the preparation of a novel electrically conductive transparent paper. The high dispersity of the MWCNTs was realized by utilizing a bacterial cellulose membrane as a template to deposit them uniformly, thereby achieving electrically conductive transparent papers with outstanding optical transparency. The light transmittance and electrical conductivity varied according to the concentration of the MWCNT dispersion. Good optimal transparency and electrical properties were obtained with a light transmittance of 70.3% at 550 nm and electrical conductivity of 2.1 × 10^?3 S/cm when the electrically conductive transparent paper was fabricated from a 0.02 wt % aqueous MWCNT dispersion. In addition, the electrically conductive transparent papers showed remarkable flexibility without any loss of their initial properties. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 46: 1235–1242, 2008     

聚乙烯复合导电塑料性能

通过将高密度聚乙烯、SEBS、导电炭黑和炭纤维等原材料混合、造粒、注塑成型等工艺制备了聚乙烯复合导电塑料样品,测试了其物理化学性能。样品具有不渗液、导电性高、耐腐蚀、其SEM图表明了样品形成导电网络,适合用作钒电池的集流体。     

Electronically conductive polymers

A concise review of papers published during the last 3 years about the synthesis, blends, processing, and applications of electronically conductive polymers, is presented in this article. Copyright © 2002 John Wiley & Sons, Ltd.     

Phthalonitrile-based conductive polymer

An aromatic, diether-linked phthalonitrile resin, prepared from 4,4′-bis(3,4-dicyanophenoxy)biphenyl, can be converted into an environmentally stable, highly conductive material by thermal means. The conductivity of the pyrolyzed polymer can be varied and controlled as a function of both the pyrolytic temperature and annealing time. This allows the generation of a range of electrical behavior from an insulator to semiconductor and approaching metallic regions.     

Electrical conductive coordination polymers

Coordination polymers are currently one of the hottest topics in Inorganic and Supramolecular Chemistry. This critical review summarizes the current state-of-the-art on electrical conductive coordination polymers (CPs), also named metal-organic frameworks (MOFs). The data were collected following two sort criteria of the CPs structure: dimensionality and bridging ligands (151 references).     

A mechanically strong conductive hydrogel reinforced by diaminotriazine hydrogen bonding

Over the past decades,the urgent need for high strength conductive hydrogels in diverse applications has motivated an unremitting effort to combine the improved mechanical properties of hydrogels with conductive performances.In this work,high strength conductive hydrogels intensified with intermolecular hydrogen bonding are fabricated by in situ mixing poly(2-vinyl-4,6-diamino-1,3,5-triazine-co-polyethylene glycol diacrylates) (PVDT-PEGDA) hydrogels with poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT/PSS).The conductive hydrogels in deionized water exhibit high mechanical performances with compressive strength and tensile strength in the range of 7.58-9.52 MPa and 0.48-1.20 MPa respectively,which are ascribed to the intermolecular hydrogen bonding interactions of diaminotriazinediaminotriazine (DAT-DAT) in the network.Meanwhile,adding PEDOT/PSS can significantly increase both the specific conductivities and equilibrium water contents of the hydrogels.These cytocompatible conductive hydrogels may have a great potential to be used as electrical stimuli responsive soft biomaterials.     

UV cured transparent films including non‐aqueous conductive microgels

UV cured transparent films containing non‐aqueous conductive microgels coated with poly(aniline)/dodecyl benzenesulfonic acid(DBSA) were obtained. The conductive microgels were prepared by interface polymerization of aniline/DBSA in the presence of non‐aqueous polymeric microgels. The electrical conductivity and the particle size of the prepared conductive microgel were 0.5 S/cm and 58 nm, respectively. The prepared conductive microgels were easily blended with a UV curable coating formulation, and then were cured to make highly optically transparent films. For the UV cured film containing about 35 wt% of the conductive microgels, a surface resistance in the range of 10⁷ to 10⁸ Ω/square was obtained. In a polar cosolvent, such as NMP and m‐cresol, the critical volume was shifted to the lower range, with a value of 10 wt%. The UV cured films containing the conductive microgels exhibited good electrical stability against the thermal aging and humidity. Copyright © 2002 John Wiley & Sons, Ltd.     

Electrochemical characterization of ionically conductive polymer membranes

Cation conductive membranes, especially highly proton conductive membranes, are of interest not only for chlor-alkali electrolysis but for polymer electrolyte fuel cells as well. The very challenge for electrochemical characterization in this case is the low specific resistance of the polymer required for such applications, which in turn makes resistance measurements a non-trivial problem. We investigate the different possibilities to characterize such membranes. The present part of our work deals with the adequate conditioning and equilibration of membranes designed especially for direct methanol fuel cell applications, with the measurement of the conductivity and with the determination of apparent transport numbers in the membrane. The usefulness of the respective leaching investigations, impedance spectroscopy measurements and concentration potential measurements for the case of membranes made from sulfonated poly(phenylene oxide) is discussed.     

A study of fine-dispersed silver powders for conductive adhesive compositions

Results of granulometric investigations of fine-dispersed silver powders are presented, and they are evaluated for use in compositions of conductive adhesives. The optimal brand of nanodispersed powder for the obtaining of conductive adhesive of EKS-2 brand characterized by ρ_v × 10^–7 Ω m is chosen.     

Enhancing corrosion resistance of zinc-filled protective coatings using conductive polymers

Organic coatings containing zinc are amply used for the protection of metals, particularly steel structures. Ways to reduce the zinc content in the coating materials are sought for environmental and financial reasons. Our previous work (Kohl, Prog Org Coat 77:512–517, 2014; Kohl and Kalendová, Mater Sci Forum 818: 171–174, 2015a) suggested that one of the options consists in the use of conductive polymers in the formulation of the zinc coatings. The benefits of conductive polymers include nontoxicity, high stability, electric conductivity and redox potential. Previously we focussed on the effect of conductive polymers added to the organic coatings so as to complete the zinc volume concentration to 67%. The anticorrosion efficiency of the organic coatings was found to improve with increasing polyaniline phosphate or polypyrrole concentrations. Zinc content reduction in the system, however, did not attain more than 5%. The present work focusses on systems where the organic coatings are prepared with zinc having a pigment volume concentration PVC = 50%. Zinc content reduction in the system attains up to 20%. This work examines the mechanical and anticorrosion properties of the organic coatings with reduced zinc contents. The present work was devoted to the feasibility of using of conductive polymers in the formulation of coatings with reduced zinc contents. The conductive polymers included polyaniline, polypyrrole and poly(phenylenediamine); these were synthesised and characterised using physico-chemical methods. Polyphenylenediamine as a potential corrosion inhibitor has not been paid adequate attention so far. Subsequently, organic coatings with reduced zinc contents and containing the pigments at 0.5, 1 and 3% volume concentrations were formulated. The coatings were subjected to mechanical tests and accelerated corrosion tests to assess their mechanical and corrosion resistance. The corrosion resistance of the organic coatings was also studied by linear polarisation. The results of the mechanical tests, accelerated corrosion tests and linear polarisation measurements indicate that the organic coating properties get affected by the conductive polymer type as well as by the pigment volume concentration. The important finding is that the use of conductive polymers in coatings with reduced zinc contents was beneficial in all cases.     

Blockcopolymers with electrically conductive microphases morphology,conductivity and crystal structure

By synthesis of TCNQ radical anion salts of poly(1,4-butadiene-b-4-vinylpyridine)(B4VP) blockcopolymers and subsequent doping with neutral TCNQ filmforming electrically conductive materials of good mechanical stability were obtained. The improved properties are achieved either by incorporation of butadiene microparticles in a coherent conductive P4VP phase or by generation of a percolating electrically conductive crystalline micronetwork embedded in a continous butadiene phase. In comparison to the homopolymers the resistance to oxidation is enhanced.     

Electrothermomechanical analysis and its application to studying electrically conductive adhesive joints

Electrothermomechanical analysis (ETMA) is effective for studying electrically conductive adhesive joints. Post curing of an electrically conductive adhesive (silver particle filled epoxy) by heating at an elevated temperature significantly enhances the thermal and mechanical stability of the conductive adhesive joint. The contact electrical resistivity and thickness of a joint tend to decrease cycle to cycle upon thermal cycling between 30 and 50°C and upon compression (up to 0.55 MPa). The effects of compression and thermal cycling are significant in the joint without post curing, but is insignificant after post curing. This revised version was published online in August 2006 with corrections to the Cover Date.     

Influence of graphene reinforcement in conductive polymer: Synthesis and characterization

Lightweight conductive polymers are considered for lightning strike mitigation in composites by synthesizing intrinsically conductive polymers (ICPs) and by the inclusion of conductive fillers in insulating matrices. Conductive films based on polyaniline (PANI) and graphene have been developed to improve through‐thickness conductivity of polymer composites. The result shows that the conductivity of PANI enhanced by blending polyvinylpyrrolidone (PVP) and PANI in 3:1 ratio. Conductive composite thin films are prepared by dispersing graphene in PANI. The conductivity of composite films was found to increase by 40× at 20 wt% of graphene inclusion compared with PVP and PANI blend. Fourier‐transform‐infrared (FTIR) spectra confirmed in situ polymerization of the polymer blend. The inclusion of graphene also exhibits an increase in Tg by 21°C. Graphene additions also showed an increase in thermal stability by approximately 148°C in the composite films. The mechanical result obtained from DMA shows that inclusion of graphene increases the tensile strength by 48% at 20 wt% of graphene reinforcement. A thin, highly conductive surface that is compatible with a composite resin system can enhance the surface conductivity of composites, improving its lightning strike mitigation capabilities.     

Electronically and ionically conductive gels of ionic liquids and charge-transfer tetrathiafulvalene-tetracyanoquinodimethane

Electronically and ionically conductive gels were fabricated by mixing and mechanically grinding neutral tetrathiafulvalene (TTF) and tetracyanoquinodimethane (TCNQ) in ionic liquids (ILs) like 3-ethyl-1-methylimidazolium dicyanoamide (EMIDCA), 1-ethyl-3-methylimidazolium thiocyanate (EMISCN), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMITf(2)N), trihexyltetradecylphosphonium bis(trifluoromethylsulfonyl)imide (P(14,6,6,6)Tf(2)N), and methyl-trioctylammonium bis(trifluoromethylsulfonyl)imide (MOATf(2)N). Charge-transfer TTF-TCNQ crystallites were generated during the mechanical grinding as indicated by the UV-visibile-near-infrared (UV-vis-NIR) absorption spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction. The charge-transfer TTF-TCNQ crystallites have a needle-like shape. They form solid networks to gelate the ILs. The gel behavior is confirmed by the dynamic mechanical measurements. It depends on both the anions and cations of the ILs. In addition, when 1-methyl-3-butylimidazolium tetrafluoroborate (BMIBF(4)) and 1-methyl-3-propylimidazolium iodide (PMII) were used, the TTF-TCNQ/IL mixtures did not behave as gels. The TTF-TCNQ/IL gels are both electronically and ionically conductive, because the solid phase formed by the charge-transfer TTF-TCNQ crystallites is electronically conductive, while the ILs are ionically conductive. The gel formation is related to needle-like charge-transfer TTF-TCNQ cyrstallites and the π-π and Coulombic interactions between TTF-TCNQ and ILs.     

高分子导热复合材料结构设计及性能研究进展

近年来,电子设备的需求逐渐向集成化、微型化发展,随之带来了愈发严重的发热问题已经成为了阻碍电子设备发展的重要因素之一。作为电子设备重要组成材料之一的高分子材料对优良导热性能的要求也越来越高,导热高分子复合材料的研究已经成为当前功能复合材料的重要发展方向。本文综述了高分子导热复合材料的发展趋势,介绍了当前选用填料法来制备单一填料、混杂填料高分子导热复合材料以及双逾渗结构、隔离结构等复杂多相结构的高分子导热复合材料的研究进展。重点介绍了通过多种导热填料的组合利用来制备高性能导热高分子复合材料。最后,对填料法高导热高分子复合材料的发展方向做出了简要展望。     

A novel method for the production of conductive ring spun yarn

To take the advantages of spun yarns such as porosity, softness, bending as well as usability as yarn/fabric forms, this study worked on an alternative conductive yarn production method. Different from widely used application methods, a conductive nanosuspension was applied to viscose, cotton and polyester open fibre bundles with different feeding amounts during the ring spinning with a specially developed apparatus. Reduced graphene oxide (rGO) synthesized with a single step process instead of two-step processes was used to impart conductivity. Following to yarn production, winding, knitting and washing processes were realized to evaluate the changes in yarn conductivity and the usability of the yarns in the post-spinning processes. In addition to tensile properties of the yarns and air permeability of the fabrics, electrical resistance and environmental impact of the method was compared with immersion and drying process. The results indicated that alternative method allows the production of conductive (lower resistance than 100 kΩ) but also strong, flexible, washable and breathable electronic textile products with an environmentally friendly process. There has been no effort, as yet, to get conductivity in this manner. Therefore, the developed method can be considered to be a new application in the functional yarn production field. The produced conductive yarns can be converted into fabric form by weaving, knitting and embroidery. Therefore, they can also be seen as an ideal as the platforms for future wearable electronics.

     

Organic vapor sensing behaviors of carbon black/poly (lactic acid) conductive biopolymer composite

Carbon black (CB)/poly (lactic acid) (PLA) conductive biopolymer composite were fabricated by casting. A low percolation value (1.25 vol%) is achieved due to the formation of a two-dimensional conductive network in the composite. Vapor sensing behaviors of the CB/PLA conductive composite were studied. A high chemical selectivity with respect to different organic vapors and a good reproducibility to two typical solvents, ethyl acetate and ethanol, during exposure-drying runs have been demonstrated. The variations of the sensing behaviors during exposure-drying processes were associated with the evolvement of CB conductive networks. The results indicate that the Flory-Huggins interactions parameter x ₁₂, related to the solubility parameter (thermodynamic factor), molar volume (kinetic factor) and the measurement temperature, affects the vapor sensing behaviors of CB/PLA composite significantly. These results suggest CB/PLA conductive biopolymer composite can be applied as a nice vapor sensor candidate.     

Preparation of stable aqueous conductive ink with silver nanoflakes and its application on paper‐based flexible electronics

A new kind of stable aqueous conductive ink with silver nanoflakes was developed, which was also used to fabricate conductive patterns on weighing paper for flexible electronics by direct writing. Silver nanoflakes of different sizes were characterized by transmission electron microscopy. The physical properties of the conductive ink were investigated by a dynamic contact angle system, Ubbelohde viscometer, and a surface tension instrument. Conductive properties of paper‐based conductive patterns were also investigated by 4‐point probe, scanning electron microscopy, X‐ray diffraction and Uscan explorer with a 3D profilometer system. It is demonstrated how the formulation of conductive ink affects the surface morphology, microstructure conductivity, and line width of conductive patterns. It can be obtained that the paper‐based conductive patterns have low resistivity. Especially, when the sintering condition is 200 °C for 20 min, the resistivity can be down to 9.4 μΩ?cm. The application of the ink on an antenna for radio frequency identification was also studied. Copyright © 2011 John Wiley & Sons, Ltd.