1,721,003 research outputs found
Epoxy Resin Catalyzed by Graphite-Based Nanofillers
No full textGraphene stacks/epoxy nanocomposites were produced and characterized in order to analyse the effect of different graphene precursors on cure reaction of a model epoxy matrix. A kinetic analysis of the cure mechanism of the epoxy resin associated to the catalytical activity of the graphite based fillers was performed by isothermal DSC measurements. The DSC results showed that the addition of all graphite based fillers greatly increased the enthalpy of epoxy reaction and the reaction rate, confirming the presence of a catalytic activity of graphitic layers on the crosslinking reaction between the epoxy resin components (epoxide oligomer and di-amine). A kinetic modelling analysis, arising from an autocatalyzed reaction mechanism, was finally applied to isothermal DSC data, in order to predict the cure mechanism of the epoxy resin in presence of the graphite based nanofiller
Advancements in tailoring PEDOT: PSS properties for bioelectronic applications: A comprehensive review
Full text linkIn the field of bioelectronics, the demand for biocompatible, stable, and electroactive materials for functional biological interfaces, sensors, and stimulators, is drastically increasing. Conductive polymers (CPs) are synthetic materials, which are gaining increasing interest mainly due to their outstanding electrical, chemical, mechanical, and optical properties. Since its discovery in the late 1980s, the CP Poly(3,4-ethylenedioxythiophene):poly (styrene sulfonic acid) (PEDOT:PSS) has become extremely attractive, being considered as one of the most capable organic electrode materials for several bioelectronic applications in the field of tissue engineering and regenerative medicine. Main examples refer to thin, flexible films, electrodes, hydrogels, scaffolds, and biosensors. Within this context, the authors contend that PEDOT:PSS properties should be customized to encompass: i) biocompatibility, ii) conductivity, iii) stability in wet environment, iv) adhesion to the substrate, and, when necessary, v) (bio-)degradability. However, consolidating all these properties into a single functional solution is not always straightforward. Therefore, the objective of this review paper is to present various methods for acquiring and improving PEDOT:PSS properties, with the primary focus on ensuring its biocompatibility, and simultaneously addressing the other functional features. The last section highlights a collection of designated studies, with a particular emphasis on PEDOT:PSS/carbon filler composites due to their exceptional characteristics
Novel Supercapacitor Based on Pedot:PSS/Graphene Oxide Nanocomposite
No full textOver the last few years, graphene oxide (GO) has stood out as an ideal carbon-filler to dope polymer matrix, specifically conductive polymers. This paper investigates the possibility of producing ternary nanocomposites based on a conductive polymer poly(3,4 ethylene dioxythiophene) polystyrene sulfonate (PEDOT:PSS), doped with graphene oxide (GO) and is additivated with a green dispersing and reducing agent (ascorbic acid). Three-component inks have been developed and their rheological and surface tension properties are studied to evaluate their filmability. Subsequently, through the drop-casting technique, thin films of the inks are produced, and their electrochemical behavior is deeply analyzed via cyclic voltammetry tests (CV). Particularly, PEDOT:PSS/GO/AA ink shows a higher specific capacitance (Csp) up to 29.84 mF cm−2 than pristine PEDOT:PSS, suggesting that this ink can be used as an electrode material for supercapacitor devices
Polymer-based nano-inks for solar cells
No full textPolymer-based nano-inks represent a versatile class of materials exploited in fundamental materials science as in cutting-edge technologies. An intelligent selection of polymer and filler can generate a library of nanocomposites with programmable functionalities. Owing to this exceptional and facile tunability of solid-state physical–chemical properties and broad prospects for applications, polymer-based nano-inks are envisioned as cornerstone constituent of next-generation, low-cost optoelectronic devices.
In the last decade, the surge of hybrid halide perovskite materials represented a fundamental breakthrough in contemporary optoelectronics, particularly in solar cells; therefore, numerous strategies have been explored for incorporating polymer-based nano-inks into halide perovskite-based photovoltaic devices. Polymeric materials have been exploited in different fashions, as to improve the processability, mechanical robustness and moisture tolerance of perovskite materials, and to fabricate more efficient transporting layers or printable electrodes for perovskite solar cells
Biodegradable extruded thermoplastic maize starch for outdoor applications
No full textIn the recent years, great progress was achieved in the development of biodegradable products based on agricultural raw
materials. Among them, one of the most promising and diffused biomaterials is represented by starch. For this reason,
different approaches have already been explored to use starch as a natural source for the production of biodegradable
thermoplastic polymers. However, there is still a lack of a controlled, easy and cheap procedure to process maize native
starch in order to obtain a highly performing thermoplastic polymer. The purpose of this paper is the development of a
simple and reproducible method able to produce a thermoplastic starch that can be easily transformed into extruded objects,
suitable for several potential applications. To reach this aim, a proper plasticizer was added to a commercial maize starch at
different concentrations corresponding to mass fraction from 50 to 70% (in the following text %). The effect of the
different amounts of the plasticizer on the processability of the starch powder was assessed by varying the parameters
during the extrusion process. The interaction of the structure of starch with the plasticizer, firstly, and the final thermal and
physical–mechanical properties of the extruded thermoplastic starch samples, secondly, were analysed by using several
techniques: differential scanning calorimetry, thermogravimetric analysis, X-ray diffraction, scanning electron microscopy,
UV transmittance, moisture absorption, colorimetric and mechanical tests. The samples containing 50% of plasticizer, in
possess of the best physical and thermal performances, were further characterized in terms of durability, in order to predict
their lifetime in outdoor conditions, by using artificial ageing tests, such as moisture absorption and QUV accelerated
weathering tests
GO/glucose/PEDOT:PSS ternary nanocomposites for flexible supercapacitors
Full text linkPoly(3,4 ethylenedioxythiophene)polystyrene sulfonate (PEDOT:PSS), among the most used
conductive polymers, shows properties easily modulating by adding fillers as Graphene Oxide
(GO). Recently, PEDOT-based polymers have been used with encouraging results as electrodes for
flexible supercapacitors. We have already developed a green ternary nanocomposite based on
PEDOT:PSS doped with GO and glucose (GGO-PEDOT) with a specific capacitance of 16 F/g,
indicating how this nanocomposite is potentially suitable to be used as an electrode material for a
supercapacitor. In this work, a free-standing nanocomposite film was realized by drop casting the
solution in a proper silicone mould, followed by peeling and thermal annealing. Specific analyses,
such as thermogravimetric, colorimetric and contact angle measurements, have been performed
aiming at assessing the stability of the thermal and of the surface properties, even in severe moisture
and UV aging conditions.
Finally, The capacitive performance of PEDOT:PSS and of GGO-PEDOT was investigated by
means of cyclic voltammetry (CV), in the pristine conditions and under UV aging. The deposited
GGO-PEDOT film showed a good conductive behaviour and stability under UV treatment of 4
hours
Polymeric rheology modifier allows single-step coating of perovskite ink for highly efficient and stable solar cells
Full text linkDeveloping environmental friendly solution-processed hybrid perovskite films, with a compelling combination of reproducibility and moisture stability, is a highly desirable prospect to foster hybrid perovskite solar cells uptake in a fiercely competitive high-tech market. Herein, starch biopolymer is exploited as a rheological modifier to tailor the viscosity of perovskite precursor solutions, in order to allow the development of stable inks that can be straightforwardly deposited in a single coating step at mild-temperature, without the use of toxic solvents, to obtain uniform perovskite thin films. Importantly, the as conceived methylammonium lead iodide (MAPbI3) perovskite-starch composite film, integrated in a fully solution processed planar solar cell architecture, featured high power conversion efficiency of 17.2%, which is the highest reported for polymer-perovskite blends, improved moisture stability, more than 800 h stored in humid environment (50%), and resistance to bending stress in flexible devices. Moreover, it is worth to highlight how transmittance and thickness of the composite films can be simply adjusted by varying the perovskite inks viscosity with starch, envisioning the future implementation of such hybrid perovskite composites in printing technology and in different optoelectronic devices
Rheological and physical characterization of PEDOT: PSS/graphene oxide nanocomposites for perovskite solar cells
Full text linkIn this work, the influence of graphene oxide (GO) doped Poly(3,4 ethylenedioxythiophene):poly
(styrenesulfonate)(PEDOT:PSS) thin nanocomposite on an indium–tin-oxide (ITO) anode, as hole
transport layer (HTL) in perovskite solar cells, was investigated. Different concentrations of GO were
added into the PEDOT:PSS in order to enhance its conductivity. In particular, the influence of GO
content on the rheological and thermal properties of Poly(3,4-
ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS)/GO nanocomposites was initially
examined. The GO filler was prepared by using modified Hummers method and dispersed into
PEDOT:PSS in different quantity (ranging from 0.05 to 0.25 %wt/wt). The obtained nanocomposite
solutions were analyzed by rheological characterizations in order to evaluate the influence of the GO
filler on the viscosity of the PEDOT:PSS matrix. The wettability of solutions was evaluated by
Contact Angle (CA) measurements. The quality of GO dispersion into the polymer matrix was studied
using Scanning electron microscopy (SEM) and X-ray diffraction (XRD). Thermal characterizations
(DSC and TGA) were, finally, applied on nanocomposite films in order to evaluate thermal stability
of the films as well as to indirectly comprehend the GO influence on PEDOT:PSS-water links
Microwave-induced porosity and bioactivation of chitosan-PEGDA scaffolds: morphology, mechanical properties and osteogenic differentiation
No full textIn this study, a new foaming method, based on physical foaming combined with microwave-induced curing, is proposed in combination with a surface bioactivation to develop scaffold for bone tissue regeneration. In the first step of the process, a stable physical foaming was induced using a surfactant (Pluronic) as blowing agent of a homogeneous blend of Chitosan and polyethylene glycol diacrylate (PEGDA700) solutions. In the second step, the porous structure of the foaming was chemically stabilized by radical polymerization induced by homogeneous heating of the sample in a microwave reactor. In this step, 2,2-azobis[2-(2-imidazolin-2yl)propane]dihydrochloride was used as thermoinitiator (TI). Chitosan and PEGDA were mixed in different blends to investigate the influence of the composition on the final properties of the material. The chemical properties of each sample were evaluated by infrared attenuated total reflectance analysis, before and after curing in order to maximize reaction yield and optimize kinetic parameters (i.e. time curing, microwave power). Absorption capacity, elastic modulus, porosity and morphology of the porous structure were measured for each sample. The stability of materials was evaluated in vitro by degradation test in phosphate-buffered saline. To improve the bioactivity and biological properties of chitosan scaffold, a biomineralization process was used. Biological characterization was carried out with the aim to prove the effect of biomineralization scaffold on human mesenchymal stem cells behaviour. Copyright © 2016 John Wiley & Sons, Ltd
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