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The exploitation of methylammonium lead iodide perovskite-polymer composites is a promising strategy for the preparation of photoactive thin layers for solar cells. The preparation of these composites is a simple fabrication method with improved moisture stability when compared to that of pristine perovskite films. To deepen the understanding of the charge transport properties of these films, we investigated charge carrier mobility, traps, and ion migration. For this purpose, we applied a combinatory measurement approach that proves how such composites can still retain an ambipolar charge transport nature and the same mobility values of the related perovskite. Furthermore, thermally stimulated current measurements revealed that the polymer influenced the creation of additional defects during film formation without affecting charge mobility. Finally, impedance spectroscopy measurements suggested the addition of starch may hinder ion migration, which would require larger activation energies to move ions in composite films. These results pave the way for new strategies of polymer-assisted perovskite film development.

Highly conductive PEDOT:PSS is one of the most promising materials for indium tin oxide (ITO) substitution in printed electronics. Here, we report the development and optimisation of two PEDOT:PSS ink formulations for the fabrication of inkjet-printed transparent conductive layers. Starting from aqueous commercial solutions, co-solvents and a non-ionic surfactant were employed to modify the surface tension, improve the wetting capability of the ink, and obtain uniform and homogeneous thin films. In particular, the quantities of ethanol and surfactant were systematically adjusted to determine the optimal conditions for inkjet printing. The results demonstrate that a surface tension value between 28 and 40 mN/m and approximately 40 vol.% of a low-boiling-point co-solvent are fundamental to ensure the proper wetting of the glass substrate and a quick-drying process that confers uniformity to the printed thin film. The printed PEDOT:PSS thin films show good morphological, optical, and electrical properties that are similar to those observed for the corresponding spin-coated layers. The organic light-emitting diodes (OLEDs) fabricated with the inkjet-printed PEDOT:PSS electrodes showed a maximum quantum efficiency of 5.5% and maximum current efficiency of 15 cd/A, which is comparable to spin-coated reference devices. These results demonstrate the great potential of polymeric electrodes for the fabrication of high-efficiency printed OLED devices that are compatible with flexible and stretchable substrates.

Summary High-throughput manufacturing of hybrid halide perovskite solar cells is the next challenge before they enter the market. An anti-solvent bath is generally required to control the perovskite film assembly starting from precursors in solution. Although an anti-solvent bath has proven feasible for roll-to-roll deposition, it implies an undoubted increased complexity of the manufacturing line, meaning enhanced costs for the process itself and anti-solvent disposal. Here, we take advantage of the use of a starch polymer as a rheological modifier in perovskite precursor solutions to avoid the anti-solvent bath. Starch allows for control of the perovskite growth process in one step and reach of required viscosities for gravure-printing technique with ∼50% less of the raw precursor materials. This combined with simplified processing conditions are expected to drastically lower the costs of perovskite material production. We demonstrate that this approach can be upscaled to roll-to-roll gravure printing of flexible solar cells, reaching a maximum power conversion efficiency close to 10%.

In this study, an original and green procedure to produce water-based solutions containing nanometric recycled carbon particles is proposed. The nanometric particles are obtained starting from carbon waste ashes, produced by the wooden biomass pyro-gasification plant CMD (Costruzioni motori diesel) ECO20. The latter is an integrated system combining a downdraft gasifier, a spark-ignition internal combustion engine, an electric generator and syngas cleaning devices, and it can produce electric and thermal power up to 20 kWe and 40 kWth. The carbon-based ashes (CA) produced by the CMD ECO20 plant were, first, characterized by using differential scanning calorimetry (DSC) and microcomputed tomography (microCT). Afterward, they were reduced in powder by using a milling mortar and analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectrometry, thermogravimetric analysis (TGA), X-ray diffraction (WAXD) and Fourier-transform infrared (FTIR) spectroscopy. The optimization of an original procedure to reduce the dimensions of the ashes in an aqueous solution was then developed by using ball milling and sonication techniques, and the nanometric dimensions of the particles dispersed in water were estimated by dynamic light scattering (DLS) measurements in the order of 300 nm. Finally, possible industrial applications for the nanomaterials obtained from the waste ashes are suggested, including, for example, inks for Aerosol Jet® Printing (AJ® P). ispartof: Nanomaterials vol:11 issue:3 ispartof: location:Switzerland status: published

In this study, carbon based ashes were produced by the wooden biomass pyro-gasification plant CMD ECO20. CMD ECO20 is a micro-scale combined heat and power system powered with biomass, under development by the Italian company Costruzioni Motori Diesel (C.M.D) S.p.A. It is an integrated system combining a downdraft gasifier, a spark ignition internal combustion engine, an electric generator and syngas cleaning devices, and it is able to produce electric and thermal power up to 20 kWe and 40 kWth. Three different types of fillers were produced from ashes starting from innovative green waste: the first type (MA) was obtained by mortar milling, while the second (DBA) and the third (WBA) one were produced by dry and wet ball milling, respectively. MA, DBA e WBA fillers were characterized by several techniques including Scanning Electron Microscopy (SEM), Multi-angle light scattering (MALS) and Energy Dispersive X-ray (EDX) Spectrometry. Each filler was added to epoxy resin EC01 in an amount equal to 1, 3, 5 and 10 wt%. The curing agent (22phr) was added to the resin that was cured for 1 h at 60 °C and 2 h at 150 °C. Finally, the flexural properties and the glass transition temperature of the cured neat epoxy and ashes filled epoxy composites were measured. The elastic modulus of the epoxy resin containing an amount of fillers from 1 to 10 wt% is higher in comparison to that of the neat epoxy. The flexural strength of the epoxy resin containing an amount of DBA of 3 wt% is also higher than that of the neat epoxy.

The industrialization of perovskite solar cells relies on solving intrinsic-to-material issues. To reach record efficiencies perovskite deposition needs to be finely adjusted by multi-step processes, in a humidity free glove-box environment and by means of hardly scalable techniques often associated with toxic solvents and anti-solvent dripping/bath. Herein, the use of polymeric material is proposed to deposit perovskite layers with easy processability. To the scope, a starch-polymer/perovskite composite is developed to suit slot-die coating technique requirement, allowing the deposition of hybrid halide perovskite material in a single straightforward step without the use of toxic solvents, and in uncontrolled humid environment (RH up to 70 %). The starch-polymer increases the viscosity of the perovskite precursor solutions and delays the perovskite crystallization that results in the formation of perovskite films at mild temperature (60 degrees C) with good morphology. These innovative inks enables the fabrication of flexible solar cells with p-i-n configuration featured by a power conversion efficiency higher than 3 %. . Overall, this approach can be exploited in the future to massively reduce perovskite manufacturing costs related to keeping the entire fabrication line at high-temperature and under nitrogen or dry conditions.

The aim of this work is the development and characterization of biodegradable thermoplastic recycled carbon ashes/maize starch (TPAS) composite films for agricultural applications. A proper plasticizer, that is, glycerol, was added to a commercial maize starch in an amount of 35 wt.%. Carbon-based ashes were produced by the biomass pyro-gasification plant CMD ECO 20, starting from lignocellulosic wastes. The ashes were added to glycerol and maize native starch at different amounts ranging from 7 wt. % to 21 wt.%. The composite was mixed at 130 &deg, C for 10 min and then molded. The effect of the different amounts of carbon based ashes on the thermal and physical-mechanical properties of the composite was assessed by using several techniques, such as rheology, wide- angle X-ray diffraction (WAXD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), moisture absorption, degradation and mechanical tests. The presence of the carbon waste ashes allows to improve thermal and durability performances of the thermoplastic starch (TPS) films. It reduces the water absorption of starch matrix and strongly decreases the deterioration of starch, independently from fillers amount, enhancing the lifetime of the TPS films in outdoor conditions. In addition, the waste carbon ashes/maize starch films present an advantage in comparison to those of neat starch, it can biodegrade, releasing the plant nutrients contained in the ashes into the soil. In conclusion, this approach for recycling carbon waste ashes increases the efficiency of industrial waste management, along with a reduction of its impact on the environment.

In 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.

Semi-transparent perovskite-based solar cells feature competitive levels of transparency and efficiency, envisioning their future application in building integrated photovoltaics. However, complex processing conditions and thermal stability, inherent of hybrid halide perovskite materials, remain urgent issues to be solved. Herein, the interaction with perovskite precursors and transparency in the visible range of cellulose polymer are explored for the realization of semi-transparent perovskite-polymer composite. Hydroxyethyl cellulose inclusion in CH3NH3PbI3 was found to have several beneficial effects, namely, to simplify processing conditions, to improve the average visible transmittance of ~44% and, foremost, to enhance the thermal stability without compromising photovoltaic performances of semi-transparent perovskite solar cells. A maximum light utilization efficiency (LUE) of 2.4% corresponding to a power conversion efficiency of 11.6% was demonstrated, which is in the range usually required for window applications, positioning these semi-transparent solar cells among the most efficient ones reported to date.

In this study, two different fillers were prepared from carbon-based ashes, produced from the wooden biomass of a pyro-gasification plant, and starting from lignocellulosic waste. The first type was obtained by dry ball-milling (DBA), while the second one was prepared by oxidation in H2O2 of the dry ball-milled ashes (oDBA). The characterization of the fillers included wide-angle x-ray diffraction (WAXD), thermogravimetric, and Fourier-transform infrared spectroscopy (FTIR) analysis. The DBA and oDBA fillers were then tested as possible catalysts for the crosslinking reaction of a diglycidyl ether of bisphenol A (DGEBA) with a diamine. The cure reaction was studied by means of rheometry and differential scanning calorimetry (DSC). The oDBA filler exhibits both a higher catalytic activity on the epoxide&ndash, amine reaction than the DBA sample and improved mechanical properties and glass transition temperature. The results obtained indicate, hence, the potential improvement brought by the addition of carbon-based waste ashes, which allow both increasing the flexural properties and the glass transition temperature of the epoxy resin and reducing the curing time, acting as a catalyst for the crosslinking reaction of the epoxy resin.

The performances of organometallic halide perovskite-based solar cells severely depend on the device architecture and the interface between each layer included in the device stack. In particular, the interface between the charge transporting layer and the perovskite film is crucial, since it represents both the substrate where the perovskite polycrystalline film grows, thus directly influencing the active layer morphology, and an important site for electrical charge extraction and/or recombination. Here, we focus on engineering the interface between a perovskite-polymer nanocomposite, recently developed by our group, and different commonly employed polymeric hole transporters, namely PEDOT: PSS [poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate)], PEDOT, PTAA [poly(bis 4-phenyl}{2,4,6-trimethylphenyl}amine)], Poly-TPD [Poly(N,N&prime, bis(4-butylphenyl)-N,N&prime, bis(phenyl)-benzidine] Poly-TPD, in inverted planar perovskite solar cell architecture. The results show that when Poly-TPD is used as the hole transfer material, perovskite film morphology improved, suggesting an improvement in the interface between Poly-TPD and perovskite active layer. We additionally investigate the effect of the Molecular Weight (MW) of Poly-TPD on the performance of perovskite solar cells. By increasing the MW, the photovoltaic performances of the cells are enhanced, reaching power conversion efficiency as high as 16.3%.

Sources of single photons are a fundamental brick in the development of quantum information technologies. Great efforts have been made so far in the realization of reliable, highly efficient, and on demand quantum sources that could show an easy integration with quantum devices. This has recently culminated in the use of solid state quantum dots as promising candidates for future sources of quantum technologies. However, some challenges, like their complex fabrication, random distribution, and difficult integrability with silicon technology, could hinder their broad application, making necessary the study of alternative systems. In this work, we clearly demonstrate single photon emission from quantum dots formed in nonstoichiometric bulk perovskites. Their simple growing procedures, exceptional stability under constant illumination, easy control of their optical properties, as well as ease of integrability make these materials very interesting candidates for the development of quantum light sources in the near-infrared.

In 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.

Herein, an insulating biopolymer is exploited to guide the controlled formation of micro/nano-structure and physical confinement of alpha-delta mixed phase crystalline grains of formamidinium lead iodide (FAPbI(3)) perovskite, functioning as charge carrier concentrators and ensuring improved radiative recombination and photoluminescence quantum yield (PLQY). This composite material is used to build highly efficient near-infrared (NIR) FAPbI(3) Perovskite light-emitting diodes (PeLEDs) that exhibit a high radiance of 206.7 W/sr*m(2), among the highest reported for NIR-PeLEDs, obtained at a very high current density of 1000 mA/cm(2), while importantly avoiding the efficiency roll-off effect. In depth photophysical characterization allows to identify the possible role of the biopolymer in i) enhancing the radiative recombination coefficient, improving light extraction by reducing the refractive index, or ii) enhancing the effective optical absorption because of dielectric scattering at the polymer-perovskite interfaces. Our study reveals how the use of insulating matrixes for the growth of perovskites represents a step towards high power applications of PeLEDs. Funding Agencies|Regione Puglia through Samset2018 [r_puglia/A00_137/PROT/17/07/2017/001578]; MIUR (Italian Ministry of University and Research) through PRIN PERovskite-based Solar cells: towards high Efficiency and lOng-term stability (PERSEO) [20155LECAJ]; Fondazione di Sardegna - Convenzione triennale tra la Fondazione di Sardegna e gli Atenei Sardi Regione Sardegna [L.R. 7/2007, F72F16003040002]; SIR project "Two-Dimensional Colloidal Metal Dichalcogenides based Energy-Conversion Photovoltaics" (2D ECO), Bando SIR (Scientific Independence of young Researchers) 2014 MIUR Decreto Direttoriale 23 gennaio 2014 [197, RBSI14FYVD, CUP: B82I15000950008]; Regione Puglia; ARTI [LSBC6N4, GOWMB21]; China Scholarship Council

Developing 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.

Polymeric nanocomposites based on UV in situ reduced graphene oxide were developed in order to enhance the electrical conductivity of polymeric matrices for the realization of highly efficient solid-state hybrid solar cells based on organometal trihalide perovskite absorbers. Graphene is a 2-D single layer of sp2-bonded carbon atoms characterized by high specific surface area, Young's modulus, thermal stability, mobility of charge carriers and plus fascinating transport phenomena such as the quantum Hall effect. Among several developed methods to prepare graphene, including chemical vapor deposition (CVD) and mechanical exfoliation, the chemical reduction of graphene oxide (GO) is regarded as the most promising for future implementation in large-scale production. In this work, a GO prepared by a modified Hummers method was used and reduced by a green method based on UV treatment in inert atmosphere. Graphene oxide reduction was monitored evaluating the change of absorption peak by UV-visible spectroscopy and X-ray photoelectron spectroscopy (XPS), monitoring the decrease of the oxygen groups linked to carbon. Dilute nanocomposites suspensions were then prepared by optimizing the dispersion procedure of GO in the polymeric matrix as function of process parameters, i.e. time, temperature and composition. Nanocomposite films were also realized by spin coating on different substrates and characterized by several techniques. At last the film showing the better properties was implemented in a hybrid solar cell to evaluate the increase of electrical conductivity and power conversion efficiency.

Poly (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 h.

The present work is focused on the design of a bioactive chitosan-based scaffold functionalized with organic and inorganic signals to provide the biochemical cues for promoting stem cell osteogenic commitment. The first approach is based on the use of a sequence of 20 amino acids corresponding to a 68-87 sequence in knuckle epitope of BMP-2 that was coupled covalently to the carboxyl group of chitosan scaffold. Meanwhile, the second approach is based on the biomimetic treatment, which allows the formation of hydroxyapatite nuclei on the scaffold surface. Both scaffolds bioactivated with organic and inorganic signals induce higher expression of an early marker of osteogenic differentiation (ALP) than the neat scaffolds after 3 days of cell culture. However, scaffolds decorated with BMP-mimicking peptide show higher values of ALP than the biomineralized one. Nevertheless, the biomineralized scaffolds showed better cellular behaviour than neat scaffolds, demonstrating the good effect of hydroxyapatite deposits on hMSC osteogenic differentiation. At long incubation time no significant difference among the biomineralized and BMP-activated scaffolds was observed. Furthermore, the highest level of Osteocalcin expression (OCN) was observed for scaffold with BMP2 mimic-peptide at day 21. The overall results showed that the presence of bioactive signals on the scaffold surface allows an osteoinductive effect on hMSC in a basal medium, making the modified chitosan scaffolds a promising candidate for bone tissue regeneration.

This article compares the catalytic activities of oxidized carbon black (oCB) and graphene oxide (eGO) samples on the kinetics of a reaction of diglycidyl ether of bisphenol A (DGEBA) with a diamine, leading to crosslinked insoluble networks. The study is mainly conducted by rheometry and Differential Scanning Calorimetry (DSC). Following the same oxidation procedure, CB samples are more efficiently oxidized than graphite samples. For instance, CB and graphite samples with high specific surface areas (151 and 308 m2/g), as oxidized by the Hummers’ method, exhibit O/C wt/wt ratios of 0.91 and 0.62, respectively. Due to the higher oxidation levels, these oCB samples exhibit a higher catalytic activity toward the curing of epoxy resins than fully exfoliated graphene oxide.

S.C. and A.L. acknowledge Regione Puglia and ARTI for funding FIR—future in research projects “PeroFlex” project no. LSBC6N4 and “HyLight” project no. GOWMB21. The authors acknowledge the project Progetto di ricerca PON MAAT (Project Number: PON02_00563_3316357) and PERSEO-“PERovskite-based solar cells: towards high efficiency and long-term stability” (Bando PRIN 2015-Italian Ministry of University and Scientific Research (MIUR) Decreto Direttoriale 4 novembre 2015 n. 2488, project number 20155LECAJ) for funding. A.R. and S.M. gratefully acknowledge SIR project “Two-Dimensional Colloidal Metal Dichalcogenides based Energy-Conversion Photovoltaics” (2D ECO), Bando SIR (Scientific Independence of young Researchers) 2014 MIUR Decreto Direttoriale 23 gennaio 2014 no. 197 (project number RBSI14FYVD, CUP: B82I15000950008) for funding. The authors acknowledge Sonia Carallo for technical support. N.D.T. acknowledges support from the National Science Foundation's International Research Fellowship Program (OISE-1201915) and the European Research Council's Marie Curie International Incoming Fellowship under grant agreement number 300091. N.S. is by a European Research Council Starting Independent Researcher Fellowship under grant agreement number 279587. We thank Dr. Detlef-M. Smilgies from the Cornell High Energy Synchrotron Source (CHESS) for his assistance with in situ GIWAXS measurements. CHESS is supported by the NSF & NIH/NIGMS via NSF award DMR-1332208. A.A. and R.M. are thankful for the support of the King Abdullah University of Science and Technology (KAUST) and the KAUST Solar Center.

Hybrid organic-inorganic halide perovskites have emerged at the forefront of solution-processable photovoltaic devices. Being the perovskite precursor mixture a complex equilibrium of species, it is very difficult to predict/control their interactions with different substrates, thus the final film properties and device performances. Here the wettability of CH3NH3PbI3 (MAPbI(3)) onto poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) hole transporting layer is improved by exploiting the cooperative effect of graphene oxide (GO) and glucose inclusion. The glucose, in addition, triggers the reduction of GO, enhancing the conductivity of the PEDOT:PSS+GO+glucose based nanocomposite. The relevance of this approach toward photovoltaic applications is demonstrated by fabricating a hysteresis-free MAPbI(3) solar cells displaying a approximate to 37% improvement in power conversion efficiency if compared to a device grown onto pristine PEDOT:PSS. Most importantly, V-OC reaches values over 1.05 V that are among the highest ever reported for PEDOT:PSS p-i-n device architecture, suggesting minimal recombination losses, high hole-selectivity, and reduced trap density at the PEDOT:PSS along with optimized MAPbI(3) coverage.

Polymer nanocomposites properties significantly depend on the average size of the fillers dispersed into the matrix and on the grade of the dispersion, the latter influenced by the process techniques. In this work, we determined the aspect ratio of graphene oxide (GO) dispersed into Poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS), starting from the indirect measurement of the rheological behavior of polymer/filler mixtures, as a function of the shear rate and the volumetric composition. PEDOT:PSS+GO nanocomposite films were also realized by spin coating on different substrates and characterized by Scanning electron microscopy (SEM) and X-ray diffraction (XRD), in order to analyze the quality of the dispersion, even by direct measurements.

The influence of different graphite-based nanofillers on epoxide ring opening reactions, as induced by amines for diglycidyl ether of bisphenol A (DGEBA), is studied. Direct kinetic studies, with full chemical characterization and quantitative evaluation of the low molecular mass products, for reactions of DGEBA with primary and secondary monoamines as well with alcohols, are conducted. Moreover, the kinetic behavior of a commercial epoxy resin based on DGEBA and a diamine, leading to crosslinked insoluble networks, is studied by indirect methods, such as differential scanning calorimetry (DSC) and rheometry. The reported results show a relevant catalytic activity of graphene oxide on epoxy resin crosslinking by amines. For instance, for a graphene oxide content of 3 wt%, the exothermic crosslinking DSC peak is shifted (upon heating at 10 °C min−1) from 113 °C down to 96 °C, while the gel time at 50 °C is reduced by a factor of 2.5. This behavior is due to the ability of graphene oxide to catalyze primary amine–epoxy, secondary amine–epoxy and mainly hydroxyl–epoxy additions.

Inthis paper, we have investigated the possibility to realize a nanocomposite buffer layer for perovskite solar cells, based on polyelectrolyte poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) PEDOT:PSS and graphene oxide (GO). To this aim, GO, prepared by a modified Hummers method, was mixed with PEDOT: PSS by solvent swelling method and reduced in situ into the polymer matrix through a green and simple method, by using UV radiation. Thin nanocomposite layers were spin coated on different substrates and characterized by several techniques. GO reduction was first analyzed by XPS analyses, monitoring the decrease of the intensity of the peak of the oxygen groups linked to carbon. The grade of the dispersion of GO into PEDOT: PSS was also analyzed by scanning electron microscopy. Sheet resistance measurements of the films with and without GO before and after UV treatment was performed. The thermal stability of the nanocomposites was then evaluated by thermogravimetric analyses. The nanocomposite layer was finally employed in a perovskite solar cell to evaluate the effect of GO reduction on power conversion efficiency. The interface interaction between the nanocomposite and the perovskite precursors was analyzed by contact angle measurements.

Graphene 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.

In 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 WileySons, Ltd.

In this study, free-standing expanded graphite chitosan (EG-chitosan) nanocomposite films have been prepared using a novel green and simple preparation method, starting from a commercial expandable graphite (GIC). The in situ exfoliation of GIC by a solvent-free sonication method was monitored as a function of the process parameters using X-ray diffraction (XRD), transmission electron microscopy (TEM), dynamic light scattering (DLS) and UV-visible transmittance (UV-VIS) analyses. The optimal process parameters were selected in order to obtain an efficient dispersion of EG in chitosan solutions. The effective EG amount after the in situ exfoliation was also determined by thermogravimetric analyses.

This work is focused on the surface characterization of reduced graphene oxide (rGO) obtained through reduction of graphite oxide. The reduction was performed using a green method (based on UV irradiation under N2) with low environmental impact, free of additional functionalization reagents, simple and low-cost. X-ray photoelectron spectroscopy (XPS) was applied for chemical characterization of surface C species showing a significant reduction of oxygen-containing functional groups from the surface of rGO.

A significant effort was directed to the synthesis of graphene stacks/epoxy nanocomposites and to the analysis of the effect of a graphene precursor on cure reaction of a model epoxy matrix. A comparative thermal analysis of epoxy resins filled with an exfoliated graphite oxide eGO were conducted. The main aim was to understand the molecular origin of the influence of eGO on the Tg of epoxy resins. The higher Tg values previously observed for low curing temperatures, for epoxy resins with graphite-based nanofillers, were easily rationalized by a catalytic activity of graphitic layers on the reaction between the epoxy and amine groups of the resin, which leads to higher crosslinking density in milder conditions. A kinetic analysis of the cure mechanism of the epoxy resin associated to the catalytical activity of the graphite based filler was performed by isothermal DSC measurements. The DSC results showed that the addition of graphite based filler 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 auto-catalyzed 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.

We have developed a novel and straightforward approach for the green synthesis of reduced graphite oxide (rGO). First, graphite oxide (GO) was prepared by the Hummers' oxidation method, starting from high-surface-area graphite. Then, rGO was generated from GO in aqueous suspension through a UV-irradiation treatment. The influence of different process parameters (including type of UV source, irradiation time and atmosphere) on the GO reduction efficiency was explored and evaluated on the basis of the data acquired by several experimental techniques, such as infrared spectroscopy in attenuated total reflectance mode, X-ray diffraction, UV-vis absorption spectrophotometry, X-ray photoelectron spectroscopy and thermogravimetry. The acquired results allowed identifying appropriate sets of reaction conditions under which GO reduction yield could be maximized. In particular, the highest reduction degree was obtained by exposing GO to UV light in a UV oven for 48 h under inert atmosphere. The reduction strategy developed by us represents an innovative low-cost and easy route to graphene-based nanomaterials, which does not require any stabilizer, photocatalyst or reducing agent. For this reason, our method represents an attractive environmentally friendly alternative approach for the preparation of stable rGO dispersions in large-scale amounts, to be utilizable in disparate engineering applications.

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In this work, a mixture of a sodium salt of carboxymethylcellulose (CMCNa) and polyethylene glycol diacrylate (PEGDA700) was used for the preparation of a microporous structure by using the combination of two different procedures. First, physical foaming was induced using Pluronic as a blowing agent, followed by a chemical stabilization. This second step was carried out by means of an azobis(2-methylpropionamidine)dihydrochloride as the thermoinitiator (TI). This reaction was activated by heating the sample homogeneously using a microwave generator. Finally, the influence of different CMCNa and PEGDA700 ratios on the final properties of the foams was investigated. The viscosity, water absorption capacity, elastic modulus and porous structure were evaluated for each sample. In addition, preliminary biological characterization was carried out with the aim to prove the biocompatibility of the resulting material. The foam, including 20% of PEGDA700 in the mixture, demonstrated higher viscosity and stability before thermo-polymerization. In addition, increased water absorption capacity, mechanical resistance and a more uniformmicroporous structurewere obtained for this sample. In particular, foam with 3% ofCMCNa shows a hierarchical structure with open pores of different sizes. This morphology increased the properties of the foams. The full set of samples demonstrated an excellent biocompatibility profile with a good cell proliferation rate of more than 7 days. © 2013 The Author(s) Published by the Royal Society. All rights reserved.