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Item type:Publication, Access status: without files , Erratum: On the manufacturing and electrical and mechanical properties of ultra-high wt.% fraction aligned MWCNT and randomly oriented CNT epoxy composites (Carbon (2015) 91 (275-290))(Elsevier, 2015-11-14); ; ; ; Publicationtype: Journal Article60 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , On the manufacturing and electrical and mechanical properties of ultra-high wt.% fraction aligned MWCNT and randomly oriented CNT epoxy composites(Elsevier, 2015-05-02); ; ; ; The effect of CNT orientation on electrical and mechanical properties is presented on the example of an ultra-high filler loaded multi-walled carbon nanotube (68 wt.% MWCNTs) epoxy-based nanocomposite. A novel manufacturing method based on hot-press infiltration through a semi-permeable membrane allows to obtain both, nanocomposites with aligned and randomly oriented CNTs (APNCs and RPNCs) over a broad filler loading range of ≈10-68 wt.%. APNCs are based on low-defected, mm-long aligned MWCNT arrays grown in chemical vapour deposition (CVD) process. Electrical conductivity and mechanical properties were measured parallel and perpendicular to the direction of CNTs. RPNCs are based on both, aligned mm-long MWCNTs and randomly oriented commercial μm-long and entangled MWCNTs (Baytube C150P, and exemplarily Arkema Graphistrength C100). The piezoresistive strain sensing capability of these high-wt.% APNCs and RPNCs had been investigated towards the influence of CNT orientations. For the highest CNT fraction of 68 wt.% of unidirectional aligned CNTs a Young's modulus of E|| ≈ 36 GPa and maximum electrical conductivity of σ|| ≈ 37·10⁴ S/m were achieved.Publicationtype: Journal Article76 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Synthesis of an organic conductive porous material using starch aerogels as template for chronic invasive electrodesWe report the development of an organic conducting mesoporous material, as coat for invasive electrodes, by a novel methodology based on the use of starch aerogel as template. The poly(3,4-ethylenedioxythiophene) (PEDOT) aerogel was synthesized by polymerization of 3,4-ethylenedioxythiophene within a saturated starch aerogel with iron (III) p-toluenesulfonate (oxidizing agent) and subsequent removal of the polysaccharide template, followed by supercritical CO2 drying. The chemical structure and oxidation state of the resulting material were studied by Raman spectroscopy. The morphology and surface properties of the obtained nanoporous material were investigated by scanning electron microscopy (SEM), micro computed tomography (μCT) and nitrogen adsorption-desorption techniques. The composition and thermal behaviour were evaluated by energy dispersive spectroscopy (EDS) and thermogravimetric analysis (TGA) respectively. A preliminary biocompatibility test verified the non-cytotoxic effects of the PEDOT aerogel. The large surface area and wide pore size distribution of the PEDOT conductive aerogel, along with its electrical properties, enable it to be used as extracellular matrix scaffold for biomedical applications.Publicationtype: Journal ArticleScopus© Citations 41 15 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Thiol-ene polymer based fast photo-curable gate insulator for organic field effect transistorsWe report the synthesis and properties of fast photo-cured polymer dielectrics used as top gate insulators in organic field-effect transistors (OFETs). Two thiol functionalized compounds and a vinyl ether monomer were used to formulate thiol-ene polymers. The kinetic of the photo-curing of these formulations was determined by monitoring the curing process by FT-IR spectroscopy. Guided by measurements on metal-insulator-metal and metal-insulator-semiconductor structures, we determined the composition of the thiol-ene polymer and the optimal time of exposure to UV-irradiation to fabricate high performance poly(3-hexylthiophene)-based OFETs. We cured a mixture of a mercapto-functionalized polysiloxane produced with sol-gel process, 1,4-cyclohexanedimethanol divinyl ether and irgacure 127 in 15 s. The produced transistors have high on/off ratios of 105. The OFETs showed a field effect mobility of 10-2 cm2 V-1 s-1 and low threshold voltage of -3 V.Publicationtype: Journal Article105 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , In vitro biocompatibility study and electrical properties of the PEDOT, PEDOT collagen coat, PEDOT nanotubes and PEDOT aerogels for neural electrodesThe aim of this study is to evaluate the cytotoxicity of Poly(3, 4-ethylenedioxythiophene) (PEDOT), PEDOT-collagen and PEDOT nanostructured coatings for neural electrodes. Incorporation of cell growth factors and the structuration of supporting material are two strategies to improve cell adhesion and biocompatibility in order to produce better and more specific neural implants. PEDOT coat, PEDOT-collagen coat, PEDOT nanotubes and PEDOT aerogel were tested for biocompability using the standard ISO 10993-5. PEDOT and PEDOT-Collagen coats were deposited via galvanostatic electropolymerization from a NaPSS micellar dispersion. In addition PEDOT nanotubes were obtained by hard polycarbonate template and PEDOT aerogels were chemically produced through a soft starch template. PEDOT samples were studied for biocompatibility, characterized by LCRmeter and Scanning electron microscopy (SEM). Biocompatibility test verified the absence of cytotoxic effects in all the PEDOT samples.Publicationtype: Journal Article104 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Effect of experimental factors on the properties of PEDOT-NaPSS galvanostatically deposited from an aqueous micellar media for invasive electrodes(IEEE, 2012-12); ; ; Poly(3,4-ethylenedioxythiophene) (PEDOT) coat for invasive electrodes has been generated considerable interest in terms of electrical properties and biocompatibility. Adequate formulations and methodology are necessary to deposit polymer reproducibly on macro and micro-electrodes. Electrochemical properties of PEDOT as interface material were assessed with respect to different experimental factors. PEDOT/NaPSS was polymerized from a sodium polystyrenesulfonate (NaPSS) dispersion. The dispersion was characterized by cyclic voltammetry and its critical micellar concentration (CMC) value is reported, according to our best knowledge, for the first time for PEDOT deposition. The polymer obtained was studied using Raman spectroscopy, impedance and cyclic voltammetry measurement. PEDOT-NaPSS coat shows high charge injection (Qinj), low interfacial impedance (Z) and superficial chemical stability (Raman). This study provides a simple, constant and reproducible framework to coat invasive electrodes.Publicationtype: Conference Paper10 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Comparison of new conductive adhesives based on silver and carbon nanotubes for solar cells interconnection(Elsevier, 2012-11-23); ; ; ; Publicationtype: Journal Article42 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , A simulation study on the effects of shear flow on the microstructure and electrical properties of carbon nanotube/polymer composites(Elsevier, 2011-08-31); ; ; We employ a fiber-level simulation technique to simulate carbon nanotube (CNT)/polymer composites in simple shear flow. This model incorporates CNT flexibility, irregular CNT equilibrium shapes and CNT interactions. Electrical conductivity of the composites is determined using a resistor network algorithm. Tunneling resistance of the insulating matrix film between nanotubes is also considered. We show that the rate of imposed shear flow influences the composite conductivity by facilitating the formation or destruction of the conductive aggregates. In addition, the conductivity evolution during shearing for different concentrations is investigated. At low concentration, percolating clusters form and break simultaneously which causes large conductivity fluctuations during the simulations. When sufficiently large concentrations are reached, percolating clusters persist during shearing and the conductivity fluctuations decrease. In agreement with previous research we determine that increasing the shear rate causes alignment of the nanotubes in the flow direction. We show that upon shearing at constant shear rate, the system attains a state with substantially constant electrical conductivity, nanotube orientation and agglomerate size that is a function of the applied shear rate. The state reached for a given shear rate is independent of the initial state of orientation and aggregation.Publicationtype: Journal Article30 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Combined electrical and rheological properties of shear induced multiwall carbon nanotube agglomerates in epoxy suspensions(Elsevier, 2011-08-12); ; ; ; In this work the rheological and electrical properties of semi-dilute carbon nanotube (CNT)-epoxy suspensions have been discussed. The suspensions are produced using two types of industrially available CNTs (Nanocyl 3150 and 7000) and using two different dispersion techniques, namely 3-roll milling and sonication. In-situ optical microscopic analysis and electrical conductivity measurements have been conducted. It is shown that despite using CNTs with similar aspect ratios, the dispersability of the raw material and the time stability of the suspensions are quite different. Additionally, viscosity measurements are used to evaluate the initial dispersion quality and time stability.Publicationtype: Journal Article25 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Imaging mechanism of carbon nanotubes on insulating and conductive substrates using a scanning electron microscopeCarbon nanotubes (CNTs) were deposited on bare glass, Au (10 nm)/glass, and Au (50 nm)/glass substrates, and observed using a scanning electron microscope (SEM) operating at different accelerating voltages. Depending on the substrate and accelerating voltage, the CNTs exhibit different levels of contrast. On the poorly conductive glass and Au (10 nm)/glass substrates, electrons are supplied or dissipated through the networked CNTs. This generates a potential difference between the CNTs and the (insulating or poorly conductive) substrates. CNTs are visualized as a result of potential contrast. At a low accelerating voltage (1 kV), the substrate is of higher potential than that of the networked CNTs (the ground potential), and the CNTs exhibit bright contrast. At a high-accelerating voltage (5-10 kV), the potential of the substrate is lower than the networked CNTs, and the CNTs exhibit dark contrast. On the Au (50 nm)/glass conductive substrates, the electrons are supplied through both the Au film and the CNTs, and topographic morphology of CNTs is observed.Publicationtype: Journal Article17