Dielectric nanocomposites for energy, environment and health: from fundamental to devices

Resume : After 30 years of intense research, colloidal semiconductor nanocrystals are presently employed in a certain number of technologies which can be integrated into grand-public applications. Due to their small size (typically below 10 nm), these nanocrystals behave as quantum dots for the electrons (holes) and their optical properties are strongly influenced by quantum confinement effects. Up to now, semiconductor nanocrystals have been mainly studied for their linear optical response, either in absorption or luminescence. In this talk, I present numerical simulations showing that semiconductor nanocrystals could be of high interest for their non-linear response. I argue that recent progress in colloidal chemistry could be used to design nanocrystals characterized by strongly non-linear optical properties and I propose several strategies allowing to reach this goal.

Resume : Functional materials enabling a perfect trapping of light are appealing for a broad variety of applications, including contactless sensing and energy conversion. However, this may require light to be trapped over spectral windows with very different widths: narrowband for contactless sensing versus broadband for energy conversion. Although such very different spectral responses are at the reach of metamaterials based on noble metal or standard semiconductor nanostructures tailored by multistep lithography processes, this approach is not ideal for a low-cost upscaling. In here, strategies will be proposed to achieve equivalent or even more impressive light trapping - based properties in lithography-free nanocomposite metamaterials. First, it will be demonstrated that, by harnessing the hybrid plasmonic-photonic modes of noble metal nanoparticles in dielectric cavities, high-resolution contactless sensing can be achieved while avoiding optical losses in the metal. [1,2] Furthermore, it will be explained how substituting noble metals and standard semiconductors by emergent semi-metal and topological insulator materials enables perfect light trapping tuned from the ultraviolet to the far-infrared in ultra-thin nanocomposite metamaterials for energy conversion applications: photocatalysis, photodetection and thermal emission. [3-6] [1] Baraldi et al., Adv. Mater. Int. 5, 1800241 (2018) [2] Toudert et al., ACS Photon. 2, 1443 (2015) [3] Toudert et al., J. Phys. Chem. C 11, 3511 (2017) [4] Toudert et al., Opt. Mater. Express 7, 2299 (2017) [5] Toudert et al, Opt. Express 26, 34043 (2018) [6] Ghobadi et al., ACS Photon. 5, 4203 (2018)

Resume : Nanocomposite systems based on bismuth nanoparticles (Bi NPs) have received a growing interest due to the demonstration of plasmon-like resonances that can be tuned in the visible-UV region, and that have found applications for integrated photonic devices, surface enhanced spectroscopy and plasmonic enhanced photocatalysis.[1,2] Furthermore, due to the low melting temperature of Bi, these systems are also candidates for its use as optical switches by profiting from the different optical properties of solid and liquid Bi [3]. Here we study the solid-liquid phase change of Bi NPs embedded in amorphous aluminium oxide film upon nanosecond laser excitation by using single pulse real time reflectivity measurements with nanosecond resolution. The changes of the reflectivity reveal that melting takes place within the nanosecond pulse duration whereas cooling and solidification of the NPs occurs over time scales that are much longer than for bulk Bi. The solid-liquid switching time is found to depend on the nanoparticle density, and it can be controlled smoothly from 10 ns to 700 ns by adjusting the laser pulse fluence. The optical switching process is found to be repeatable more then 10,000 times without observable degradation. [1] J. Toudert, et al. J. Phys. Chem. C 121, 3511 (2017). [2] J. Toudert and R. Serna, Opt. Mater. Express 7, 2299 (2017). [3] M. Jiménez De Castro, F. Cabello, J. Toudert, R. Serna, and E. Haro-Poniatowski, Appl. Phys. Lett. 105, (2014).

Resume : In contrast to III-V or II-VI semiconductor alloys, group IV-V alloys have been the subject of much less attention up to now. Very recently, however, alloyed SiPx thin films have gained an increasing interest. Indeed, it was predicted theoretically that a monolayer of SiP is a direct bandgap semiconductor which could be promising for the development of 2D blue light emitting diodes. In this work, we investigate SiPx thin films prepared by evaporation under high vacuum. The films were prepared by co-evaporation of Si from an e-beam gun and P from a GaP decomposition source. The structural and optical properties were investigated by means of X-ray diffraction (XRD), scanning transmission electron microscopy (STEM), vibrational spectroscopies (Infrared and Raman) and photoluminescence spectroscopy. After annealing at 1100°C, the structural characterizations reveal the presence of SiP grains crystallizing in an orthorhombic structure which coexist with Si polycrystals. To further characterize the SiP alloy, DFT calculations have been carried out to get a better understanding of the features observed in both infrared and Raman spectra. The calculated spectra are found to be in excellent agreement with the experimental results. Moreover, temperature dependent photoluminescence measurements strongly suggest that SiP is an indirect bandgap semiconductor with a bandgap energy of 1.47 eV. The obtained value is in good agreement with theoretical values found in the literature.

Resume : Topological photonic systems, with their ability to host states protected against disorder and perturbation, allow us to do with photons what topological insulators do with electrons. Topological photonics can refer to electronic systems coupled with light or purely photonic setups. By shrinking these systems to the nanoscale, we can harness the enhanced sensitivity observed in nanoscale structures and combine this with the protection of the topological photonic states, allowing us to design photonic local density of states and to push towards one of the ultimate goals of modern science: the precise control of photons at the nanoscale. Here, I will discuss our effort to move these topological concepts from electrons to light, in particular at the nanoscale. We will analyze the possibility of using prism coupling systems to excite and study Dirac Plasmons in topological insulators and I will show that topological insulators nanoparticles sustain a new kind of excitation when interacting with light. This is a topological localized surface plasmon polariton obtained perturbing the nanoparticle surface electron state with light. We will see preliminary experimental results on this previously unknown light-matter mode, which focused on bulk samples and thin films of topological insulators. These effects may be useful in the areas of plasmonics, cavity electrodynamics, and quantum information.

Resume : Multiplexing color images that can be observed independently under white light in specific observation conditions is of great interest for applications to security, data storage or design. Few articles have recently demonstrated that dichroic plasmonic colors could be used to produce polarization sensitive dual-image multiplexing [1,2]. Here, we demonstrate that composite thin films containing anisotropic metallic nanoparticles can be used to print an encoded image that contains the information of three multiplexed images, which are revealed in non-polarized reflection or in polarized transmission using two different polarization angles. The proposed method can be applied to different nanoparticle shapes and implemented with different technologies. The demonstration is illustrated here by laser process, which allows printing centimetre scale images observable by eye [3]. The nanocomposite film is initially nearly color-less with metallic precursors in the form of ions, atoms and small nanoparticles (1-2 nm). A femtosecond laser grows and shapes metallic nanoparticles at the same time it tunes the size distribution and the spatial distribution of these nanoparticles in the film. The laser process results in the generation of micrometer size plasmonic nanostructured areas where the film birefringence and dichroism can be controlled at will, to produce unprecedented color gamuts that satisfy conditions for three-fold image multiplexing in three selected modes of observation. Each nanostructured area is characterized by a set of three colors corresponding to the colors exhibited in each selected mode. We further explain the conditions that the color gamuts in the three modes must fulfil to produce three-fold image multiplexing and how such conditions can be satisfied with plasmonic colors. Three-fold image multiplexing is shown using different color combinations [4]. Such laser processing is also applied to print dual multiplexed color images, for which more colors can be used. This methodology could be implemented with other technologies like electron beam lithography with a larger freedom on the choice of colors, along with a higher spatial resolution. Laser technologies however hold advantage for being more suitable for rapid and contactless printing on large surfaces. References 1- E. Heydari, J. R. Sperling, S. L. Neale and A. W. Clark, Plasmonic Color Filters as Dual?State Nanopixels for High?Density Microimage Encoding, Adv. Funct. Mater., 2017, 27, 1?6. 2- X. M. Goh, Y. Zheng, S. J. Tan, L. Zhang, K. Kumar, C. W. Qiu and J. K. W. Yang, Three-dimensional plasmonic stereoscopic prints in full colour, Nat. Commun., 2014, 5, 5361. 3- Z. Liu, M. Garcia-Lechuga, T. Epicier, Y. Lefkir, S. Reynaud, M. Bugnet, F. Vocanson, J. Solis, G. Vitrant and N. Destouches, Three-Dimensional Self-Organization in Nanocomposite Layered Systems by Ultrafast Laser Pulses, ACS Nano, 2017, 11, 5031?5040. 4- N. Sharma, M. Vangheluwe, A. Vermeulin, M. Bugnet, N. Destouches, Three-fold color image multiplexing with plasmonic films, under writing

Resume : Ion beam shaping is a novel and powerful tool to engineer nanocomposites with effective three-dimensional (3D) architectures. In particular, this technique offers the possibility to precisely control the size, shape and 3D orientation of metallic nanoparticles at the nanometer scale while keeping the particle volume constant. Here, we use swift heavy ions of xenon for irradiation in order to successfully fabricate nanocomposites consisting of anisotropic gold nanoparticle that are oriented in 3D and embedded in silica matrix. Furthermore, we investigate individual nanorods using a nonlinear optical microscope based on second-harmonic generation (SHG). A tightly focused linearly or radially-polarized laser beam is used to excite nanorods with different orientations. We demonstrate high sensitivity of the SHG response for these polarizations to the orientation of the nanorods. The SHG measurements are in excellent agreement with the results of numerical modeling based on the boundary element method.

Resume : Silicon nanocrystals (Si NCs) are the subject of an intense research activity, due to their optical and electronic properties. As in the case of bulk semiconductors, the fine tuning of their optical and electronic properties is related to the effective capability to control doping, i.e. incorporation of atoms such as phosphorous or boron within these nanostructures. We present in this study the elaboration, the structural and optical properties of SiO1.5 thin films doped with boron. The alloys were prepared by co-evaporation of SiO and SiO2 from two electron-beam guns in an ultrahigh vacuum chamber. Boron was supplied by a Knudsen cell for the low contents and from an electron beam gun for the high contents. The films were annealed at different temperatures until 1100°C in order to obtain the dismutation of SiO1.5 which results in Si NCs embedded in a SiO2 matrix. The structural and optical properties were studied by transmission electron microscopy (TEM), Fourier transform infrared absorption spectrometry and by photoluminescence (PL) experiments. Si NCs are observed by TEM in the annealed samples. Infrared absorption spectrometry allows us to follow the dismutation process and to observe an absorption band at 1380 cm-1 attributed to the O-B bonds. For low annealing temperatures, the PL spectra show bands attributed to defects. For annealing temperatures greater than 700°C, a band attributed to the Si NCs appears near 800 cm-1. This band disappears for high boron contents.

Resume : Metal-organic frameworks (MOFs) are hybrid materials built up from organic molecules coordinated to metal ions or clusters. They have been originally developed for their tunable porosity interesting for industrial applications such as gas storing and sensing. Conversely, the research on luminescent MOFs nanocrystals is still at the early stage. The peculiarity of these nanocrystals is the possibility to pack chromophores close enough to allow a fast exciton diffusion, but sufficiently far from to preserve the electronic properties of an isolated ligands. However, most of the MOFs nanocrystals synthesized showed poor fluorescence quantum yield. Here, we realize a MOF nanocomposite with an unprecedented photoluminescence emission efficiency of 70% by a proper passivation of nanocrystal surface in a polymeric host. Moreover, we show how the confinement of triplets pairs in small MOF nanocrystals can enable a triplet-triplet annihilation yield of 100% regardless the excitation conditions, thus generating efficiently upconverted fluorescence. Using a rubber polymer doped with triplet sensitizers, we fabricated an upconverting nanocomposite working at subsolar irradiance. Our results demonstrate that the photophysical properties of these nano-structures, similarly to colloidal semiconductor quantum dots, are dominated by surface states and demonstrate a practical methodology to realize highly luminescent and industrially processable nanocomposites for photonic applications.

Resume : All-inorganic cesium lead halide perovskite nanocrystals (CsPbX3 NCs, X = Cl, Br, I) attract much attention due to their high photoluminescence quantum yields and narrow emission bands with wide tunability. They combine the advantages of perovskites and quantum dots creating an exceptional material for low-cost optoelectronic and photovoltaics. Conducting low-voltage electron energy loss spectroscopy on individual NCs, we provide novel insights regarding three important aspects of their microscopic behavior: (i) we explicitly demonstrate the relation between NC size and shape with their bandgap, and that the effective coupling between proximal NCs causes band structure modifications [1]; (ii) the synthesis of CsPbX3 NCs inevitably yields simultaneous formation of other nanostructures, insulating Cs4PbBr6 nanohexagons and hybrid nanospheres [2]; and (iii) drop-casted NCs merge spontaneously at room conditions by seamless stitching of aligned NCs, it can be accelerated by humidity and mild-temperature treatments, while arrested with electron beam irradiation [3]. Further, by using high-resolution induced absorption and emission spectroscopies, we obtain detailed information on carrier dynamics in perovskite NCs [4], their water-resistant encapsulation [5], and on energy exchange within their ensembles [6]. Finally, we discuss the most recent results on efficient carrier multiplication in CsPbI3 NCs [7]. [1] J. Lin et al. Nano Lett. (2016) [2] C. de Weerd et al. J. Phys. Chem. C (2017) [3] L. Gomez et al. ACS Applied Materials & Interfaces (2018) [4] E. M. L. D. de Jong et al. J. Phys. Chem. C (2017) [5] L. Gomez et al. Nanoscale (2017) [6] C. de Weerd et al. J. Phys. Chem. C (2016) [7] C. de Weerd et al. Nature Communications (2018)

Resume : We report a simple and scalable fabrication route of a new 2D material/ 0D clusters heterostructures, exploiting the self-organized growth over 2D material (graphene, or transition metal dichalcogenide) of epitaxial flat core-shell Al based nanoclusters assemblies.[1] Once implemented into into tunnel junctions, our 2D-0D heterostructures demonstrate well-defined robust and reproducible Coulomb blockade oscillations. Interestingly, these single electron features are preserved on devices with record contact areas of 100 µm² while such transport signatures are usually limited to nanoscale patterned devices in the 100 nm2 range. Finally, we unveil for the first time the spintronics properties of 2D-0D heterostructures, opening new avenues for 2D material spintronics.[2] Referencies : [1] F. Godel et al., Advanced Materials, 29, 1604837 (2017) [2] L.D.N. Mouafo et al., Advanced Materials, 30, 1802478 (2018)

Resume : Transparent electrodes (TE) are critical materials for many devices in strategic technological areas such as photovoltaics (PV) and flexible electronics. In the case of thin film PV, the thickness of the TE must be reduced with respect to standard bulk solar cells, this being a big issue in terms of electrical and optical properties. The need of simultaneously good electrical, optical and structural properties for TE pushes to study new materials with respect to the standard TCOs (transparent conductive oxides) largely employed today, often containing expensive and toxic elements such as In. In this work we present experimental results on SiO2/Ag/SiO2 multilayer structures. The presence of the Ag intralayer and the very low thickness (only a few tens of nm) of this material produces very good electrical and optical properties (Rsh = 10 ?/? and ). In alternative to the TCO/Ag/TCO structure, the presence of the SiO2 can also a guarantee a good passivation of the interfaces. The quality and robustness of the SiO2/Ag/SiO2 has been investigated also in the case of depositions onto plastic substrates used for mechanical bending tests. In some cases, specific thermal annealing processes have been exploited to induce a partial de-wetting of the Ag film after sputtering deposition, in order to obtain a sort of Ag grid made of interconnected Ag islands. Samples have been characterized by UV-VIS-NIR spectrophotometry, 4-points electrical probe, RBS and SEM. Computer simulations have been performed to better understand the behavior of these structure and their potential applications. Our results suggest that SiO2/Ag/SiO2 can be successfully employed in several fields where ultrathin TE are critical materials.

Resume : Polarization-sensitive Surface Enhanced Raman Scattering (PS-SERS) experiments are key for a full understanding of the SERS re-radiation enhancement from anysotropic nanoantennas and nanoantenna gratings. PS-SERS is also viewed as a potential tool for probing the Raman polarizability tensor at the single molecule level and/or the orientation of molecules absorbed on metal nanostructures. In this review talk we will provide a summary of the state of the art of the last 15 years experimental findings, together with new results highlighting the intriguing wavelength-dependent polarization rotation properties of gold nanorods arrays and nanoclocks.

Resume : Gas sensing is receiving increasing attention driven by the need to ensure human safety by monitoring pollutant gases in the atmosphere such as NO2. Gas sensors based on metal oxides operating at room temperature are of great interest due to their energy saving and cost effective characteristics. Among the different materials investigated so far there is NiO, even if there are only a few reports regarding the low-cost fabrication of high-performance NiO-based sensors. In this work, we designed and fabricated a novel NiO nanofoam by a low-cost approach and applied it for the detection of NO2 at room temperature [1]. Ni(OH)2 nanowalls were directly synthesized onto interdigitated contacts by chemical bath deposition and converted into a 3D network of NiO nanoparticles (30-50 nm in size) through thermal annealing. Sensing tests showed a high response to NO2 at room temperature even for the lowest concentration of 140 ppb. In addition, the sensor presented an excellent selectivity at room temperature vs high concentrations of acetone, methane, CO, CO2, H2. The unique characteristics of the NiO nanofoam make it a potential candidate also for other applications such as electrochemical (bio)sensing, catalysis, energy storage. [1] M. Urso et al. Submitted.

Resume : The plasmonic properties of Au nanoparticles are nowadays well established along several sensor technologies. The Surface Enhanced Raman Scattering effect is just one of the examples, but has the peculiarity to be used as a characterization spectroscopy,[1] for contrast agents detection [2-4] or as a quantitative analytical tool.[5] One of the most important pre-requisite about an efficient SERS substrate, is that it should present as much as possible allowable hot spots, that are commonly tips or junctions with enhanced local fields. For this reason, large efforts were done on shape nano-gold in many different ways, but clustered gold nanospheres still seems to remain the best choice in terms of effort needed versus SERS efficiencies. Nevertheless, their intrinsically irregularity makes people skeptical about their usage. It is our believing that it could be solved by a better understanding about the role played by the hot spots on such irregular nanostructures and how all the surfaces contribute to the overall SERS enhancement factor. A model based on Boundary Element Method simulations is proposes as a versatile tool to interpret experimental extinction spectra of aggregated gold nanoparticles and to accurately predict the overall colloidal SERS EF. 1 G. Sciutto Analytica chimica acta 991 (2017) 2 F. Bertorelle Nanoscale 10 (2018) 3 F. Biscaglia Advanced Healthcare Materials (2017) 4 L. Litti Nanoscale 10 (2018) 5 L. Litti Journal of colloid and interface science 533 (2019)

Resume : Lanthanide doped fluoride-based nanoparticles are very interesting for their possible use in modern technological applications, in particular as diagnostic probes in nanomedicine. In this presentation, we focus on binary (e.g. CaF2 or SrF2) and ternary (e.g. KY3F10) fluoride nanoparticles, activated with lanthanide ions (such as Yb3+, Nd3+, Tm3+, Er3+), prepared by hydrothermal synthesis1-2. Near infrared laser excitation at 980 nm or 800 nm of the nanoparticles can excite the lanthanides and induce strong emissions in the ultraviolet, visible and near infrared range. The variation of the emission intensities with temperature give rise to interesting thermometric properties of the nanomaterials. In particular, the thermal sensitivity and resolution can be evaluated by a ratiometric approach using emissions in different optical ranges. The nanoparticles under investigation show high sensitivities in the biological windows. A core@shell architecture of the nanofluorides is also considered to enhance their emission efficiency and also the performance as nanothermometers. References 1. Cortelletti, P.; Skripka, A.; Facciotti, C.; Pedroni, M.; Caputo, G.; Pinna, N.; Quintanilla, M.; Benayas, A.; Vetrone, F.; Speghini, A., Tuning the sensitivity of lanthanide-activated NIR nanothermometers in the biological windows. Nanoscale 2018, 10 (5), 2568-2576. 2. Pedroni, M.; Cortelletti, P.; Cantarelli, I. X.; Pinna, N.; Canton, P.; Quintanilla, M.; Vetrone, F.; Speghini, A., Colloidal nanothermometers based on neodymium doped alkaline-earth fluorides in the first and second biological windows. Sensor Actuat B-Chem 2017, 250, 147-155.

Resume : Surface-enhanced spectroscopy techniques using plasmonic nanoantenna- or metasurfaces help to reduce the detection limit for biochemical sensing. While infrared spectroscopy is an excellent tool to identify a molecular species, a typically expensive IR light source is needed. We propose a spectroscopy technique based on the thermal emission of III-V semiconductor metasurfaces. The all-semiconductor metamaterial thermal emitter serves as a radiation source. A molecular layer grafted on the surface modulates the emission spectrum analogously to the modulation achieved in surface enhanced infrared absorption spectroscopy (SEIRA). We obtained qualitatively equal sensitivities comparing SEIRA and thermal emission spectroscopy using a metamaterial perfect absorber or thermal emitter functionalized with a monolayer of a trimethoxysilane compound. The vibrational fingerprints of this monolayer are detected due to the electromagnetic field enhancement obtained with the plasmonic metasurface. We probe the molecular vibrations based on the difference of the emittance measurements of the functionalized and non-treated metamaterial thermal emitter. Experimental observations of the enhanced molecular emission were confirmed using rigorous coupling wavelength analysis simulations. In sum, the experimental setup proposed is reduced because the metasurface acts simultaneously as radiation source and sensor chip. This innovative approach, surface enhanced thermal emission spectroscopy (SETES), is appealing for miniaturization and integration of sensing devices.

Resume : The elusive nature of the misfolded protein species and their molecular interactions in the neuronal system, which are involved in neurodegenerative disorders (Alzheimer?s, Parkinson?s, dementia with Lewy bodies, etc.), are among the failure causes of the clinical approaches in any diagnosis or treatment attempted so far. Thus current research is extensively devoting efforts in unravelling the basis of the disease onset including the formation mechanism of aberrant protein species and the extreme structural variability in their toxic intermediates. Surface enhanced Raman spectroscopy (SERS) is well recognized as a powerful tool in detecting biomolecular species present in traces in liquid environments including body fluids. This technique can reveal important structural features such as elements of secondary structures and exposed aminoacidic residues of proteins, which can play a primary role in ruling intra- and inter-molecular interactions in a neuronal environment. The aberrant interactions of toxic misfolded protein intermediates with neurons, specifically with the components of the neuronal membrane, eventually lead to neurodegeneration through a cascade of biochemical processes. In this work, plasmonic optofluidic platforms of differently shaped silver nanoparticles were designed and fabricated with the aim of setting up SERS systems for label-free direct detection and analysis of proteins and biomarkers associated with neurodegenerative diseases such as Alzheimer?s and Parkinson?s. Typically, silver nanocubes and nanowires were synthesized and assembled through controlled methods to build up 2D patterned nanostructures with intense SERS activity. By means of tunable dewetting processes inside a microwell or a confined drop evaporation over hydrophobic matrices, the interaction pathways between the SERS active area and the analyte can be addressed to enrich the hot spot regions of the system with the target molecules, in turn improving effectiveness and sensitivity. Beyond a sensible and reproducible detection of various model and real biomolecular species these SERS platforms allowed an accurate structural analysis of toxic oligomers of beta-amyloid, which are recognized among the main biomarkers of the Alzheimer?s disease. References: [1] M.Banchelli, C. Amicucci, E. Ruggiero, C. D?Andrea, M. Cottat, D. Ciofini, I. Osticioli, G. Ghini, S. Siano, R. Pini, M. de Angelis, P. Matteini, Submitted for publication, (2018). [2] M. Banchelli, M. de Angelis, C. D?Andrea, R. Pini, P. Matteini, Sci. Rep. 8, 1033, (2018). Acknowledgments: M.B., C.D?A., M.de A., R.P. and P.M. acknowledge the European Community within the EuroNanoMed3 ERANET cofund (H2020) project ?Surface-enhanced Raman scattering with nanophotonic and biomedical amplifying systems for an early diagnosis of Alzheimer?s disease pathology SPEEDY? (ID 221) and the Tuscany Region within the FAR FAS 2014 line A- project "Development of biophotonic sensors for OGM determination in the environment SENSOGM"

Resume : Chemical sensors based on metal oxide nanomaterials are among the most used devices for the detection of gaseous compounds during the environmental, safety, health and food quality monitoring. Gas sensor technologies are still developing and have yet to reach their full potential in capabilities and usage. Therefore, the improvement of metal oxides? sensing properties remains a challenging issue for the fabrication of low power consumption and small size chemical sensors. Graphene oxide (GO) and reduced graphene oxide (RGO) have unique properties that can revolutionize performances of functional devices. Herein, we report the synthesis and gas sensing properties of a composite material based on RGO and TiO2 nanotubes. We obtained TiO2 nanotubes by electrochemical anodization. GO was produced from natural graphite using a modified Hummers method and was reduced through the thermal reduction procedure. The morphological, compositional and structural analysis of obtained materials were performed. We systematically investigated the gas-response dependence from RGO loading and its reduction degree, showing the occurrence of an optimal RGO concentration arising from the interplay of these two parameters. In addition, the obtained results showed that RGO sheets improve the charge transport through the TiO2 tubular arrays enhancing the conductance of sensing material. Meanwhile, a depletion layer is formed between the n-type TiO2 and RGO sheets which plays an essential role for the improvement of the material sensing response. The obtained results indicate that we have developed a novel efficient approach for the coupling of GO with the metal oxide nanomaterials to fabricate high performance gas sensors and other functional devices.

Resume : Composite materials have been fabricated by combining mechanically strong carbon nanomaterials with energy rich pseudo capacitive conducting polymers to obtain better supercapacitors. This work presents the ionic liquid assisted electrochemical fabrication and characterization of conducting polymer/reduced graphene oxide composite films. Electrochemical preparation offers possibility to prepare the materials directly on various substrates using easily controllable conditions. Ionic liquids used were choline bis(trifluoromethylsulfonylimide) [Choline][TFSI] and imidazolium based IL (1-butyl-3-methylimidazolium tetrafluoroborate [Bmim][BF4]). As conducting polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) and polyazulene (PAz) were applied. The materials were studied by cyclic voltammetry and electrochemical impedance spectroscopy. Our results show that the composite materials possess higher capacitances than neat polymer films in three-electrode configuration. The obtained composite films also exhibit excellent cycling stabilities retaining over 90 percent of their initial capacitance after 1200 cycles. In composite materials, the two components interact with each other in a unique manner. It is possible to probe these interactions by combining electrochemistry with spectroscopy in in situ spectroelectrochemical techniques which enable the simultaneous monitoring of the electrochemical properties and the changes in both chemical and electronic structure. Our work has also aimed at understanding these interactions by using two in situ spectroelectrochemical techniques: in situ FTIR and in situ UV-Vis spectroscopy.

Resume : Graphene-based materials have been extensively explored in recent years as valuable candidates as the key material for novel structures in the field, among many other applications, of sensing devices. Reduced Graphene Oxide (rGO) is a type of chemically derived graphene, with equivalent optical properties but easier to be synthetized. This work reports a study about the applicability of rGO as a support for gold nanoparticles (AuNPs). AuNPs are prepared with an economic and eco-friendly method using phytochemicals present in tea extract at room temperature, while a modified Hummer?s method is used to synthesize rGO. Transmission electron microscopy (TEM), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX) were used to characterize the AuNPs. The resulting AuNPs-rGO composites will be studied in terms of UV-Vis spectroscopy spectral light transmission and plasmonic resonance and evaluated as a possible sensing element for a photonic protein sensor device. The overall analysis is supported by simulation results, obtained with DDSCAT numerical software, about the LSPR effect in AuNPs-rGO.

Resume : Statistically, we chew around 800 times in an average meal; that?s almost a million times a year. We put our teeth under huge mechanical strain, and often require fillings to repair them. Fillings are typically made of a mixture of metals, such as copper, mercury, silver and tin, or composites of powdered glass and ceramic. Typical metal fillings can corrode and composite fillings (thus far) are not very strong; Graphene on the other hand is 200 times stronger than steel and doesn?t corrode, making it a prime new candidate for dental fillings. Graphene can, therefore, be used to make mechanically stronger composite-dental fillings which also do not corrode. Despite some challenges and the fact that carbon nanotubes-polymer composites are sometimes better in some particular performance, graphene-polymer composites may have wide applications in dentistry due to their outstanding properties and the availability of graphene in a large quantity and at low cost. One of the main problems, for patients, associated with dental-polymers is that of location. This stems from the fact they must be situated within the mouth and this proves to be an extremely demanding setting, where exposure to moisture, high temperatures, and abrasion from tooth brushes plus intake of food all have to be dealt with. These conditions can lead to complications such as mechanical failures which negate clinical success and over time mandates remedial work for restoration with associated cost and inconvenience. Graphene has potential applications in dental-polymer materials as it has the required mechanical properties as well as being biocompatible. Here we present new work into the application of graphene for the fabrication of potential dental-polymer materials.

Resume : There is significant research effort focused on sustainable energy and technologies designed to improve energy efficiency. Along this line, the fabrication of environmentally friendly energy storage devices such as capacitors with high energy density is of great interest. We report on the fabrication of large-area all-carbon capacitors composed of multilayer stacks of carbon nanomembranes as dielectrics sandwiched between two carbon-based conducting electrodes. Carbon nanomembranes are prepared from aromatic self-assembled monolayers of phenylthiol homologues via electron irradiation. Two types of carbon-based electrode materials, (1) trilayer graphene made by chemical vapor deposition and mechanical stacking and (2) pyrolyzed graphitic carbon made by pyrolysis of cross-linked aromatic molecules, have been employed for this study. The capacitor area is defined by the width of electrode ribbons, and the separation between two electrodes is tuned by the number of CNM layers, with a precision of 1 nm. Working ACCs with an area of up to 1200 ?m^2 were successfully fabricated by a combination of bottom-up molecular self-assembly and top-down lithographic approaches. Then ACCs were characterized by Raman spectroscopy, helium ion microscopy, and impedance spectroscopy. A dielectric constant of 3.5 and an average capacitance density of 0.3 ?F/cm^2 were derived from the obtained capacitances. A dielectric strength of 3.2 MV/cm was determined for CNMs embedded in graphene electrodes with the interfacial capacitance being taken into account. These results show the potential of carbon nanomembranes to be used as dielectric components in next-generation environment-friendly carbon-based energy storage devices.

Resume : Polyurethane (PU) foams are used in a widespread range of applications such as insulators and dielectric materials, but their applicability is limited due to their poor mechanical properties. It seems appealing to modify PUs using nanoparticles. One-dimensional carbon nanotubes (CNTs) and two dimensional graphene nanoplatelets (GNPs) owing to their unique properties can be used as hybrid nanofillers to form well dispersed three-dimensional networks, which can overcome the dispersion problem of single nanofillers. CNTs and GNPs have a self-assembling ability due to the ? ?? interaction, which could decrease aggregations, resulting in enhancing the contact area between nanofillers and the polymer matrix. Micromechanical modeling and mechanical properties of PU hybrid nanocomposite foams with MWCNTs and GNPs were studied by mean of tensile strength and modified Halpin?Tsai equation. Three types of GNPs with various flake sizes and specific surface areas (SSA) were used to study GNP types dependence on the synergistic effect of MWCNT/GNP hybrid nanofillers. The results exhibit an outstanding synergetic effect between MWCNTs and GNPs with a flake size of 1.5 ?m and a higher SSA, which tensile strength of PU was enhanced by 43% as compared to 19% for MWCNTs and 17% for GNPs at 0.25 wt%.

Resume : Since 2004 when the graphene material had been discovered, the studies have been focused to use it in multiple applications because of its fascinating properties. There are many substrates used for graphene growth such as copper, nickel and then can be transferred to other substrates such as dielectrics; SiO2 and Al2O3 using the traditional method of exfoliation. Atomic Layer Deposition (ALD) tool is used for dielectric deposition with different thickness to ensure the uniformity of growth. This paper will represent the direct growth of graphene into dielectric (Al2O3) and how can various parameters affect in the graphene quality. Actually direct growth of graphene material to various substrates open the door for many applications and make it more flexible in terms of the uniformity of growth and other challenges that was faced during the traditional exfoliation process. On the other hand, commercial Anodic Alumina Oxide (AAO membrane) is used a base substrate as well for direct growth of graphene in this paper. This kind of membrane is considered as insulator with various pore sizes 20 ? 200 nm and thickness of 50um. Planer Tech CVD is used for this purpose of graphene growth with monitoring the pressure and temperature as well as the flow rate. All these parameters will impact directly into graphene quality in terms of conductivity and the representation of the graphene peaks. Raman Spectroscopy with 532-wavelength laser has been used in the peak analysis where the D-mode, appears at approximately 1350 cm-1, G-mode at 1452 cm-1 and 2D-mode at 2680 cm-1. Furthermore, the stupendous results conclude the growth impact by the mentioned parameters (P, T and flow rate), which were observed by utilizing different tools to prove the feasibility of results such as Atomic force microscopy (AFM). Conductive ?AFM mode has been used for electrical conductivity measurements, which is measured to be 1 nA for the growth process of 100 torr pressure, flow rate of 10 sccm and 1000C. Also, Scanning Electron Microscopy (SEM) is used for surface analysis and identifies the difference before and after the growth. The impact of manipulating between these parameters will be presented in the final paper with additional characterization.

Resume : Over the last decade, the escalating number of electronic communication devices and the greater use of microwaves radiation in advanced navigation and domestic appliances have resulted in a corresponding growth in electromagnetic interference (EMI). This inference deteriorates the performance of neighboring electronic devices and also has adverse effect on human health. Therefore, microwave absorbing materials or radar absorbing materials (RAM) which can has high absorption coefficient are requisite to overcome this problem. These RAM are also used in stealth technology to manufacture the fighter aircraft with minimum radar cross-section. The tuning of both the permittivity and permeability of the materials is important to achieve the higher microwave absorption. In this work, the EMI shielding and microwave absorbers behavior of magnetic metal(Fe, Ni, Co) filled carbon nanotube(CNT) in in 2-18 GHz frequency range is investigated. The effect of synthesis parameters such as temperature and defect generation through nitrogen doping on the microwave complex permittivity and permeability are studied and their role in achieving high EMI shielding layer is explored. Our synthesized magnetic CNTs are showing ~99% of EM attenuation. This high EM attenuation is due to the presence of Ferromagnetic resonance loss of magnetic particles along with the high ohmic loss and dielectric relaxation through polarons and bipolarons from the conducting CNTs and graphic carbon. The magnetic nanoparticles with tuned coercivity and saturation can helps in better impedance matching and the ferromagnetic resonance loss from the magnetic nanoparticles absorb the magnetic counterpart of the EM waves.

Resume : We report the facile synthesis of potassium niobate (KNbO3) nanorods (NRs) and nanocubes (NCs) with an orthorhombic phase. The orthorhombic nanostructures were synthesized via a hydrothermal method using Nb2O5 as a precursor. Furthermore, we tried to perform a low temperature in-situ hydrothermal synthesis of amorphous carbon nanotubes (A-CNTs) and reduced graphene oxide (RGO) based KNbO3 nanocompsite without the aid of any binder. This work may contribute to the synthesis of materials with new structures and hence improve the properties of the materials for various applications. Through researching the effects of reaction temperature, the optimum condition to prepare the orthorhombic potassium niobate nanostructures was investigated. The morphological and structural evolution of crystalline KNbO3 was studied in detail using X-ray diffraction (XRD), Field emission scanning electron microscopy (FESEM), High-resolution transmission electron microscopy (HRTEM), Fourier Transform Infrared Spectroscopy (FTIR), Atomic Force Microscopy (AFM) and Raman techniques. The present synthetic strategy enables us to tune the morphologies and structures of the niobate products by controlling the reaction kinetics. The reaction temperature and time need to be carefully optimized to yield high purity products with the desired crystal phase. Such a structural evolution provides a marvelous opportunity for selecting the niobate products with the desired morphologies and structures through the kinetic control of the reaction. Thus, the current study is of significant importance in developing new functional materials by wet chemical processes. Apart from this, we also tried to investigate the effect of incorporation of RGO and A-CNTs into the alkaline niobate products and observe the discerning changes in electrical properties while carrying out the impedance analysis for evaluation of dielectric properties. Till date, there are no reports of the application of RGO and A-CNTs based niobate nanocomposites in pyroelectric/ piezoelectric energy harvesting. This work may contribute to the synthesis of nanomaterials with new crystalline structures and hence improve the properties of the materials for various energy harvesting and storage applications.

Resume : Photochromic molecules are organic molecules that can be able to undergo reversible photo-isomerization between two stable states which exhibit different properties. It has been shown that polymer composites with high photochromic molecules concentration can be prepared by dissolving azobenzene and other photochromic molecules in polymers. So we presented the organic field effect transistor (OFET) device with azobenzene derivative/PMMA blending film as the dielectric layer for the ultra-violet photosensor application in the previous study. Recently, several groups have demonstrated that ion-gel based on a mixture of an ionic liquid and a polymer can be used as gate dielectrics to obtain high capacitance and charge mobility in OFET devices. It is important to obtain high value of photocurrent with low gate voltage for UV sensor application. To improve the performance of the OFET based UV sensor devices, we introduced the photochromic molecule and ion-gel blending film as the dielectric layer for the UV photosensor application. We fabricated the ion gel film based OFET devices with top-gate and top-contact type structure by simple method. The devices showed reversible photo-responses upon alternating irradiation with UV and visible light and also had an high photoresponsivity under UV light.

Resume : Photonic nanostructures are powerful instruments for controlling light on a scale smaller than the wavelength. The interest of the nano-optics is centered on the control of the optical electric field, because the response of the materials to the magnetic fields with fast oscillations is extremely weak. Materials with a significant response to the magnetic field of electromagnetic radiation do not exist in nature. But nanostructures with specific shapes or arrangements can increase their interaction with the magnetic field. We present a theoretical and numerical model, based on mixed field susceptibilities, to describe the dynamics of magnetic or electric dipole emitters induced by non-magnetic nanostructures of arbitrary shape. We extend the theory of Agarwal susceptibilities by introducing a method giving the decay rate of a dipole magnetic transition in terms of mixed magnetic field susceptibilities. We probe the decay rate maps generated by the coupling of magnetic dipole transitions with dielectric nanostructures of complex shapes and compare them to the case of electric dipole emitters. A reversal of contrast has been observed between the electrical and magnetic cases. Moreover, we demonstrate the versatility of this technique by coupling it to an evolutionary optimization algorithm. This allows us to predict structural geometries that maximize the decay of magnetic transitions.

Resume : New and smart materials are of crucial importance to improve environment quality, which is fundamental for health, wellness and life. In this work, Silicon nanostructures are proposed as a filtering material due to their high surface area. These are particular Si/SiO2 core/shell Silicon Nanowires (SiNWs) that originate from Si/SiO2 core/shell spheres acting as substrate. The structure has been studied by the combined use of Scanning and Transmission Electron Microscopy; these techniques allowed us to observe that SiNWs exhibit three kind of core/shell structures. Photoluminescence (PL) has been tested by excitation with a 405 nm laser. Furthermore, these nanostructures are non-toxic, recyclable and economic as they are a by-product of an industrial process. Tests show that these nanoparticles have the capability to decolor an aqueous solution of a commonly used organic cationic dye (methylene-blue). A probable application of these SiNWs is an integration with an already existing filtration system, such as a membrane, to enhance its filtration properties. As polymer materials are widely used for many applications, including membranes for separations, it is our intention for the future to study the dispersion of this nanofiller in a polymer matrix through a structural characterization.

Resume : The liquid phase processes are very useful for the synthesis of magnetic nanoparticles with tunable properties. In this communication we will focus on the growth cobalt based nanoparticles, their compaction into metamaterials and their final integration into devices. Our motivation is to develop new generation of permanent magnets relying on the shape anisotropy of high aspect ratio magnetic nanoparticles. Co NRs with a diameter in the range 10-30 nm and aspect ratio varying between 5 and 20 were synthesized by the polyol process [1]. Dense assemblies of Co NRs exhibiting a square M(H) loop and a magnetic volume fraction higher than 50% were prepared. Magnets with an energy product, (BH)max, of 65 and 165 kJ.m-3 at large and small scale, respectively, were obtained [2,3]. Micromagnets were for the first time successfully produced and integrated into Micro Electro Mechanical Systems using an innovative approach based on magnetophoresis, leading to an efficient electromagnetic actuation. [1] M. Pousthomis et al., Nano Research 2015, 8, 2231. [2] U. Sanyal et al., Chem. Mater. 2016, 28, 4982. [3] E. Anagnostopoulou et al., Nanoscale 2016, 8, 4020.

Resume : Luminescent semiconductor nanocrystals (NCs) based on II-VI and I-III-VI materials are characterized by intense photoluminescence (PL) band tunable over the whole visible spectral range that makes them well suited for different optoelectronic and biomedical applications. The latter put forward high requirements for their photostability and non-toxicity. The polymer coating is often used to meet these two. In the present study, the photostability of nano-composites comprising of polymer embedded with doped semiconductor NCs, have been studied. Cu and Ag doped colloidal CdSe and In2S3 NCs were synthesized in aqueous solution and transferred to polyvinyl alcohol (PVA) and gelatine. Formation of Cu(Ag)-In-S solid alloys was confirmed by optical methods. The films and aqueous colloidal solutions were irradiated for several hours at room and elevated temperatures with light causing band-to-band transitions in the NCs. It is found that irradiation of Ag-doped NCs in PVA results in the darkening of the films and decreasing in intensity of defect-related PL band. The same changes were observed for colloidal solution of Ag-doped NCs. The processes accelerated at elevated temperatures. The effect is ascribed to formation of some light-absorbing species from the residual Ag-related compounds, most probably the metallic silver. In contrast, all gelatine-based composites were found to be quite photostable indicating that gelatine is more suitable matrix for optoelectronic applications.

Resume : There are many approaches to fabricate suitable support layers to enhance osmotic water flux in forward osmosis (FO) membrane. Supporting materials in FO membrane structures are required to be porous, hydrophilic and less tortuous microstructures. Eggshell membrane, one of abundant wastes, has hydrophilic surface, highly porous and fibrous structure expected to be less tortuous. In this work, we fabricated eggshell composite membrane (ESC) applying eggshell membrane (ESM) as a support layer. The ESC membranes are simply fabricated by polyamide active layer deposition via interfacial polymerization. Also, graphene oxide was used as an additive to further improve functionality of ESC membrane. Finally, in lab scale osmosis tests, ESC membranes with low structural parameter (~138 µm) showed a considerable osmotic water flux up to 45 lm-2h-1 in FO mode using 2 M NaCl draw solution.

Resume : In this study, we used quantum chemistry calculations in order to determine some kinetic parameters of the isomerization reaction of the substituted icosadeca-ene. The studied molecules are: (C17H20, C17H12F8, C17H12Cl8, C17H12Br8 and C17H12I8) Cis and Trans. One of the adopted ways to access these parameters (activation energy, rate constant, etc ...) is looking for the transition state that is based on the exploration of intermediaries during the passage of Cis-Trans isomerization process. The study of a ten molecules series gives the following results: * The trans conformer is more stable than the Cis. * The activation energy changes very greatly depending on the size and nature of the substituent according to the reaction profile. * The constants of the isomerization reaction rates are in the following order: kC17H20 >> k C17H12F8 >> k C17H12Cl8 >>k C17H12Br8 >> k C17H12I8. * The geometrical parameters vary considerably according to intermediate products The calculation methods are DFT (TD-B3LYP) and Ab-initio methods at STO-3G*. Keywords: substituted icosadeca-ene, kinetics; isomerisation, HF (AM1+PM6), DFT

Resume : The oxidation of metal microparticles(MPs) in a polymer film yields a mesoporous highly-deformable composite polymer for enhancing performance and creating a gapless structure of triboelectric nanogenerators (TENGs). This is a one-step scalable synthesis for developing large-scale, cost-effective, and light-weight mesoporous polymer composites. We demonstrate mesoporous aluminum oxide (Al2O3) polydimethylsiloxane (PDMS) composites with a nano-flake structure on the surface of Al2O3 MPs in pores. The porosity of mesoporous Al2O3-PDMS films reaches 71.35% as the concentration of Al MPs increases to 15%. As a result, the film capacitance is enhanced 1.8 times, and TENG output performance is 6.67-times greater at 33.3 kPa and 4 Hz. The pressure sensitivity of 6.71 V/kPa and 0.18 A/kPa is determined under the pressure range of 5.5 ? 33.3 kPa. Based on these structures, we apply mesoporous Al2O3-PDMS film to a gapless TENG structure and obtain a linear pressure sensitivity of 1.00 V/kPa and 0.02 A/kPa, respectively. Finally, we demonstrate self-powered safety cushion sensors for monitoring human sitting position by using gapless TENGs, which are developed with a large-scale and highly-deformable mesoporous Al2O3-PDMS film with dimensions of 6 x 5 pixels (33 x 27 cm2).

Resume : With the advent of new technologically advances in materials science and engineering, a lot of current attention have been focused on developing electronic equipment that employs the use of shielding materials for electromagnetic interference (EMI). In this respect, a lightweight, flexible and absorbing shielding material draws a significant attention in the EMI based research community. Here, we have fabricated a flexible and light weight composite based on poly (vinylidene fluoride) (PVDF), Co doped CeO2 and RGO. A simple solvothermal method has been followed for the synthesis of Co doped CeO2 / RGO (CCR) from cobalt nitrate, cerium nitrate and graphene oxide. The fabricated composite Co doped CeO2/RGO- PVDF (CCRP) having thickness of 2 mm showed an EMI shielding effectiveness (EMI SE) value of ~30 dB in extended Ku band region at 6 wt% CCR loading. The room temperature ferromagnetic behaviour Co in CCR nanoparticles plays a vital role to enhance the EMI shielding value of the composite. The homogeneous dispersion of CCR and addition of RGO in the PVDF matrix also enhances the EMI shielding value of the composite. Thus, the fabrication of nanocomposites opens up a new avenue for developing next-generation EMI shielding materials.

Resume : Remarkable gas adsorption properties of zeolitic imidazolate frameworks (ZIFs) are believed to be tightly related to a flexible nature of organic linkers in these compounds. We present a low-frequency dielectric spectroscopy study of dynamic effects in a ZIF-90 hybrid compound. Experiments of dehydrated framework reveal slow motion of the imidazolate-2-carboxyaldehyde linker in the kilohertz frequency range. Measurements of hydrated compound indicate two additional dynamic processes related to the adsorbed water molecules. These processes are assigned to the proton conductivity and relaxation of the supercooled water confined within the pores of the framework. We also study linker dynamics of dehydrated ZIF-90 in vacuum and under different gas atmospheres, revealing that the linker motion is significantly hindered by the guest molecules. We observed a significantly lower barrier of linker movement in vacuum compared with linker dynamics in different gas atmospheres showing a tight relation between the framework motion and guest molecules.

Resume : Detecting biomolecules with heightened sensitivity is fundamental to healthcare-related researches such as disease diagnosis and treatment. Single-molecule methods are required to ultimately enhance the sensitivity of the biosensing. Among the existing single-molecule techniques, one of the major challenges for nanopore sensing is that proteins and small molecules are hard to be detected by a conventional nanopore sensing platform. Herein, we report a novel nanopipette fabrication protocol, with a small sensing area and an estimated diameter of nanopore below 10 nm, which leads to a much slower single-molecule DNA translocation. This strategy enables enhanced sensitivity of the single-molecule sensing of nanopores via the better temporal and spatial resolution of the resulting signals. This fabrication method is more affordable, easier and more stable to achieve than traditional pore fabrication methods such as focused ion beams. This innovative method is expected to bring us a leap forward towards enhancing the sensitivity.

Resume : Mechanoluminescent polymers have received arising attention in the research field of polymer science and material science in recent years. Anthracene compounds, which can photo-dimerize to form non-fluorescent dimers under 365 nm UV light irradiation and recover to the fluorescent monomers via heating or UV light of 254 nm, are good candidates of dynamic covalent systems for the research on mechanoluminescent polymeric materials. In this work, the anthracene tailored trifunctionalized polyurethane (PU) prepolymers were synthesized and these prepolymers could form crosslinked structures via the dimerization of anthracene groups under UV irradiation. The dimerizing-crosslinked polyurethanes without fluorescence showed good mechanical properties which could bearing external stress and strain. It was found that blue fluorescence was observed when these anthracene dimer crosslinked materials was pressed or scratched, indicating that the anthracene monomers were regenerated by mechanical attack chain scission of the dynamic dimer structure. 1H-NMR investigation confirmed the formation of anthracene monomers after the mechanical experiments and the process of the regeneration of the anthracene was simulated by finite element analysis. Furthermore, the average and total intensity of fluorescence increased with the increasing pressure applied on the PU materials, suggesting the formation of anthracene monomers was closely related to the external force. We hope that these anthracene dimer crosslinked PU materials could provide a new avenue for fluorescent mechanosensitive materials. (This paper is funded by the International Exchange Program of Harbin Engineering University for Innovation-oriented Talents Cultivation.)

Resume : Polymer nanocomposites incorporating nanofillers have achieved a variety of functionalities including mechanical, chemical, thermal, and electrical properties. However, the fundamental problem in such composites, poor compatibility between polymers and nanofillers, has limited the development of functionalities. Here, we demonstrate a simple and effective approach to address this issue without using compatibilizers. The plasma-assisted mechanochemistry (PMC) process can easily form covalent bonds between polymers and nanofillers even in the solid state, providing excellent processability, cost effectiveness, and environmental friendliness. Moreover, the PMC process can be applicable to nanoparticles as well as even chemically less active materials. Polyamide 66 (PA66) and hexagonal boron nitride (h-BN) were compounded via the PMC process, which can enhance the interfacial affinity between PA66 and h-BN and promote the uniform dispersion of h-BN platelets in the composites. The resulting PA66/h-BN nanocomposites exhibited significantly improved mechanical properties and thermal conductivities. In particular, the degradation in tensile strength of the composites due to the high h-BN content was completely prevented by the PMC process and the thermal conductivities of the composites were over four times higher than those of conventional composites. Therefore, this approach can provide nanocomposites with improved functionalities, thus greatly extending their applications.

Resume : Developing smart materials that respond to an external stimulus is of major interest in artificial sensing devices able to read information about the physical, chemical and/or biological changes produced in our environment. Additionally, if these materials can be integrated on flexible, transparent substrates, their appeal is greatly increased. It is well known that single crystals of molecular conductors, consisting of ion-radical salts (IRSs) typically based on tetrathiafulvalene (TTF) derivatives, exhibit striking conducting properties [1]. Such properties can be further tuned by choosing the nature of the IRSs enabling a high sensitivity towards strain, pressure, temperature or even contactless radiation; i.e. bolometers [2,3]. In the reported bilayer nanocomposite films, composed of conducting polycrystalline layers of hydroresistive sub-micron sized BEDT-TTF IRS crystals on top of a dielectric polymeric host matrix is possible to electrically monitor relative humidity in a stable and fully reversible fashion [4]. This sensor platform enables the combination of high electrical performance of single crystals with processing properties of polymers towards a simple, low-cost and highly sensitive platform for applications in robotics, biomedicine and human health care. [1] E. Laukhina, et al. Synth. Met., 102, 1785, 1999 [2] E. Laukhina, et al. Adv. Mater., 21, 1-5, 2009. [3] R. Pfattner, et al. Adv. Electr. Mater., 1, 1500090, 2015. [4] R. Pfattner et al. submitted, 2019

Resume : Dielectric polymer based composites with barium titanate nanoparticles (BaTiO3) are increasingly being developed for applications ranging from electronic packaging and embedded capacitors to energy storage and sensors, since these composites are processed at low range temperatures, are highly flexible, exhibit a low dielectric loss, relatively high dielectric constant and high dielectric strength. As for the polymer-based matrix of these composites, UV radiation-curable polymers are getting increasing relevance due to their suitability for printing and coating technologies. Further, they are environmentally-friendlier materials (no solvents are used) and require low energy for curing, when compared to other conventional heat curable products. Furthermore, this technique is fast, obtains better patterns and works at room temperature. Dielectric composites have been prepared by UV curing based on polyurethane acrylate photoactive resin and BaTiO3 filler. The influence of filler content and size on the thermal, mechanical and morphological properties will be presented and discussed. In addition, the most suitable processing conditions for tuning dielectric constant and dielectric losses will be presented as a function of filler size and content. Work supported by the Portuguese Foundation for Science and Technology (FCT) -UID/FIS/04650/2013, PTDC/EEISII/5582/2014 and SFRH/BPD/110914/2015, by the Basque Government Industry Department under the EKARTEK and HAZITEK program and by the Basque Government Education Department under project PIBA (PIBA-2018-06).

Resume : Nanoparticles bearing Surface Plasmon (SPR) and Localized Surface Plasmon Resonance (LSPR) phenomena are excellent tools for novel concepts and technologies such as the creation of bio- and chemosensors, plasmonic lasers, optical metamaterials. However, there is a number of challenges related to the use of nanoplasmonic systems associated to stability, composition and the large-scale incorporation in real devices. To address the above, we have used wet-chemical synthesis of palladium based plasmonic nanoparticles with tunable optical properties, and implemented these into suitable polymer matrixes, in order to invent cheap, easy and robust 3D ? printed nanocomposites. The nanocomposites are applied for preparation of an optical fiber hydrogen sensor. In this project Pd NCs for H2 sensing have been synthesized and successfully implemented into a PMMA matrix resulting in a H2 active nanocomposite. Effectiveness toward H2 sensing of the nanocomposite was tested with the use of a prototype sensor device, which was able to show consistent and repeatable H2 sensing response. The synthesis of nanoparticles is mainly surfactant based and is associated with a series of disadvantages that need to be mitigated such as the disruption of H2 absorption onto the Pd surface. Therefore, the impact of the surfactant on Pd Nanoplasmonic Hydrogen Sensing was explored, and several removal strategies were tested.

Resume : Free standing polymers hold significant promise in thermoelectric devices, sensors, fuel cells, as photoactive layers in solar cells and as barriers for drug permeability. Black and opaque polymers find use in the textile manufacturing, in the thermal insulation systems, as well as flexible photovoltaics. In most of these applications the bottleneck to an extensive exploitation is the manufacturability coupled to the material tribological and reliability properties. We propose an effective in-solution method based on direct acid addition to the liquid PEDOT:PSS, one of the most popular polymers. The obtained material is a black gel that can be used as it is, or deposited on the substrate or alternatively it can be peeled away becoming a free-standing, robust and flexible foil. Several types of supports have been successfully tested. Layers up to 30 microns of thickness have been deposited so far. In principle, due to the flexibility and robustness of the films, there should be no limits to the thickness that can be obtained.

Resume : The sense of touch, which is one of the most phenomenal ways of receiving information, has led to a ubiquitous need for several emerging applications, such as touch screens, mobile communications, wearable electronics, prosthetic/robotic skins and virtual reality. Even so the development of highly sensitive pressure sensors dealing with low pressure values (i.e., < 10 kPa) still remains a challenge. Very Recently, we have conducted a promising approach for polymer capacitive pressure sensors by formation of a dielectric composite layer containing zinc oxide (ZnO) nanostructure and poly(methyl methacrylate) or polydimethylsiloxane. We hypothesize that a new type of dielectric composites obtained through the addition of stress-sensitive nanostructures into polymeric matrixes may result in enhanced responses in capacitance for highly sensitive pressure sensing. Measurement results show that the ZnO-polymer capacitive pressure sensors yield a significant enhancement in pressure sensitivity, by a factor of up to 23, with respect to pristine polymer sensors. Notably, an ultrasmall load of only 10 mg (~three sesame seeds) can be reliably recognized. This approach provides a simple, convenient, and low-cost method for tiny load sensing, revealing the potency and feasibility for flexible touching & sensing electronic skin applications.

Resume : Nanofibers composed of polymer and clay have benefited from dual physical, mechanical, and biological properties of clay and flexible polymer. This work aims to prepare a bentonite-polymer nanocomposite based on expansive, inexpensive bentonite, polyvinyl alcohol, and bacterial cellulose polymer by electrospinning for wound dressing applications. The nanocomposite was synthesized using a solution intercalation technique, in which, the nano-bentonite concentration varied between 1-2 %wt. The effect of commercial and laboratory-synthesized nano-bentonite, also extract of the green walnut shell (EGWS) examined. The nanocomposites samples were characterized by scanning electron microscopy (SEM), Fourier transforms infrared (FTIR) spectroscopy. The contact angle measurement, tensile strength test, and STA analysis also were done on the prepared mat. SEM images showed that the addition of commercial nano-bentonite to the polymer, up to 2 wt %, reduces the average size of the polymer fibers, While, a sharp increase in tensile strength is measured to more than 15 MPa. Fourier transform infrared spectroscopy reveals the formation of hydrogen bonding between the nano-bentonite sheets and the polymer matrix. By the addition of synthetic nanoclay and more clearer, EGWS, a moderate elongation and strength are achieved. Hydrophilicity shows a decreasing trend up to 2 wt % of commercial nano-bentonite, however, in the laboratory-synthesized nano-bentonite was not significantly affected at all. Effects of extracts on the viability of cultured human adipose tissue-derived stem cell were quantitated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay (Sigma). Results of MTT assay showed that the sample containing 2 wt % of commercial nano- bentonite had less toxicity than other nanocomposite mats. Antibacterial activity of the mats was tested against both E. coli (gram-negative) and S. aureus (gram-positive) bacteria according to the agar diffusion test for 72 h, in which, the mats obtained by the addition of EGWS exhibited strong antimicrobial activity. Keywords: Nanocomposite, Bacterial Cellulose, Nano-bentonite, Electrospinning, PVA, Antibacterial test

Resume : Humidity sensors are of great interest in many fields because humidity plays a crucial role in several processes. Nevertheless, their application is often limited by the expensive fabrication and the stiffness of the substrates usually employed. In this work, we fabricated novel UV-curable and flexible humidity sensors based on semi-interpenetrated polymer networks. They can be prepared either as self-standing sensors or applied on different bendable substrates. The fabrication consists of a simultaneous UV-curing of an insulating network (acrylic or epoxy) and photo-polymerization of conducting polypyrrole (PPy). The detection mechanism involves proton transfer on the PPy chains that can be macroscopically observed by electrical impedance variations. These devices showed promising humidity sensing properties from 20 to 97 % of relative humidity with a maximum response of about 180 % (for epoxy-PPy). Acrylic-PPy sensors exhibited also notable response. Although it was lower than the epoxy one, acrylic-PPy sensors showed a faster recovery time. The remarkable sensing capabilities of these sensors make them a valid alternative in many applications where printability and flexibility are required along with simple fabrication method consisting of one-step-synthesis.

Resume : Polymer nanocomposites constitute an emerging class of versatile materials where the inclusion of appropriate nanofillers is intended to enhance or modify the polymer matrix properties. Such nanocomposite materials are conceived for multiple applications, spanning from agile mechanical materials or devices to drug delivery systems to sensors. In this work, composite films are prepared using polyEthilene-co-Vinyl Acetate (EVA) as the polymer matrix, and both Silicon NanoStructures (SiNSs) and Multi Walled Carbon Nanotubes (MWCNTs) as nanofillers. The SiNSs are used to investigate the optoelectronic properties of the nanocomposite films while the MWCNTs are incorporated to improve their electrical conductivity. Two different processes are compared for the film preparation, namely solvent casting and ball milling of the powder followed by their film casting via hot-pressing. The structural, electrical and optical properties of the different nanocomposite films were systematically investigated as a function of the different SiNWs and MWCNTs loadings. In particular, the loading of 15% w/w MWCNTs improved the nanocomposite electrical conductivity of several orders of magnitude, making it highly conductive. In conclusion, our study demonstrates that the easy processing of polymers associated with the peculiar properties of Si based nanostructures and MWCNTs, could give rise to a variety of novel nanocomposites which can be exploited for future applications in optoelectronics.

Resume : Scattering-type Scanning Near-field Optical Microscopy (s-SNOM) is a scanning probe approach to optical microscopy and spectroscopy bypassing the ubiquitous diffraction limit of light to achieve a spatial resolution of 10 nm. s-SNOM combines the best of two worlds, the nano-scale spatial resolution of Atomic Force Microscopy (AFM) and the analytical power of optical spectroscopy. It employs the strong confinement of light at the apex of a sharp metallic AFM tip to create a nanoscale optical hot-spot. This can be exploited for any wavelength from the visible light to the THz-region. Analyzing the scattered light from the tip interferometrically enables the extraction of the complex dielectric function (absorption, reflectivity) of the sample directly below the tip and yields nanoscale resolved optical images simultaneous to topography. Illuminating with a broadband infrared laser and detecting the elastically scattered light interferometrically (nano-FTIR) allows chemical identification of different materials in a nanocomposite with 10 nm spatial resolution. Nano-size impurities in polymer structures can be clearly detected and determined. Furthermore, plasmon modes in waveguides can be mapped with amplitude and phase, local free charge carrier densities and mobilities can be determined and even nanoscale photocurrent maps can be acquired. At last, our s-SNOM can also be used for ultrafast pump-probe experiments with down to 10 fs temporal resolution for studying fast excitation relaxation dynamics.

Resume : Photodynamic therapy (PDT) is an alternative tumor-ablative and function-sparing oncologic intervention. PDT involves three components: light, oxygen, and a phototosensitizer, which produces upon photoactivation reactive oxygenated species (ROS), or singlet oxygen (SO). These moieties are responsible for the cell-killing and therapeutic effects. Despite its proved efficiency, the use of PDT is actually limited to superficial and flat lesions, because of the tissue-penetration depth limit of visible photons required by conventional photosensitizers. A potential solution is the use of scintillating nanoparticles to activate the SO sensitizers. The large penetration depth of x-rays removes the limit for the application of PDT in deep tissues. Upon excitation by ionizing radiation, light is generated by the nanoparticles and activates the photosensitizers through energy transfer to produce SO.[1] The radiation and photodynamic therapies are therefore combined and occur simultaneously, leading to a more efficient tumor destruction. Here, it is shown how hybrid fluorescent nanotubes can serve as X-PDT agents for targeting and treatment of brain cancer. An ionic self-assembly strategy is used to functionalize the surface of synthetic chrysotile scintillating mineral nanotubes with efficient SO-sensitizer organic dyes. The dye fluorescence properties are preserved from the in vitro to the in vivo condition, and functionalized nanotubes show the ability to migrate across the blood brain barrier, thus reaching the brain tumor after injection.[2] Upon x-ray irradiation, the hybrid nanotubes work effectively as SO sensitizers inducing cellular death. Encouraging tests conducted on human-derived glioblastoma neurospheres highlight the potential of these multicomponent nanomaterials for brain cancer treatment. The simplicity of the synthesis route combined with their affinity with the in vivo condition strongly support their development as effective functional materials for broader application in the biomedical field. [1] H. Chen et al. Nano Lett. 2015, 15, 2249; [2] C. Villa et. al. Adv. Funct. Mater. 2018, 1707582.

Resume : Transparent wood is a novel composite attracting attention due to potential expanding functionality of this traditional load-bearing material into the optical domain. Delignification of wood samples with subsequent refractive index matching polymer impregnation leads to transparent wood composites, where the cell wall structure of the original wood material is fully preserved [1]. The resulting composite is highly transparent, but also features a strong haze due to anisotropic scattering [2]. Preserved wood fiber structure introduces peculiar effects on the polarization degree of the propagating light [3]. This allows wood structure characterization with visible light in contrast to traditional x-rays. For the application part incorporation of active fluorescent components, such as quantum dots [4] or fluorescent dyes [5] was also investigated. Luminescent and lasing panels or furniture components made of these hybrid materials may find utilization in general lighting, visible light communication, and in other areas. [1] Y. Li, E. Vasileva, I. Sychugov, M. Yan, S. Popov, L. Berglund, Optically transparent wood: recent progress, opportunities and challenges, Adv. Opt. Mater., 6 (2018) 1800059. [2] E. Vasileva, H. Chen, Y. Li, I. Sychugov, M. Yan, L. Berglund, S. Popov, Light scattering by structurally anisotropic media: A benchmark with transparent wood, Adv. Opt. Mater., 6 (2018) 1800999. [3] E. Vasileva, A. Baitenov, H. Chen, Y. Li, I. Sychugov, M. Yan, L. Berglund, S. Popov, Effect of transparent wood on polarization degree of light, submitted, (2019). [4] Y. Li, S. Yu, J.G.C. Veinot, J. Linnros, L. Berglund, I. Sychugov, Luminescent Transparent Wood, Adv. Opt. Mater., 5 (2017). [5] E. Vasileva, Y. Li, I. Sychugov, M. Mensi, L. Berglund, S. Popov, Lasing from Organic Dye Molecules Embedded in Transparent Wood, Adv. Opt. Mater., 5 (2017).

Resume : Approximately 90% of the world`s epoxy production relies on the use of the compound bisphenol A (BA). However, BA is a compound derived from petroleum, which makes the epoxy resin industry not environmentally sustainable as persistent demand on BA will contribute to the global warning and contamination as the exploitation of petroleum continues. Therefore, new green alternatives to BA are necessary to start the development of an environmentally sustainable epoxy resin industry. The focus of this research is to develop bio-based coatings with hydrophobic properties for anti-corrosion, anti-icing and easy cleaning applications. Two kinds of bio-based epoxy resins obtained from the oil of the cashew nutshell were utilized, together with two bio-based curing agents. The hydrophobicity of the bio-based coatings was achieved by the use of a fluorine-free additive. The thermal, mechanical and wettability properties of the bio-based thermosets were measured and the relationship with the kind of epoxy-curing agent formulation was analyzed and discussed. The anti-corrosion and anti-icing performances of the bio-based coatings were also evaluated and related to their wettability properties. Keywords: cardanol; bio-based; epoxy resin coating; hydrophobic; anti-corrosion;

Resume : Nanoparticles can be instantly generated in polymer matrices where the certain precursors are dissolved. The irradiation by light causes the photodestruction of the precursor molecules and formation of some kind of elementary species (such as atoms of gold) that further precipitate into the nanoparticles. The precipitation process is sensitive to the inpurities and inhomogeneities [N. Sapogova et al., Phys. Chem. Chem. Phys. 18, 32921?32930 (2016)] of the matrix. Utilization of segregated block copolymers as matrices can provide periodical inhomogeneities in a controllable way. In this work we perform the numerical modeling of the precipitation process of metal atoms in segregated matrices. We show that generation of nanoparticles in those matrices can lead to the fabrication of novel type of plasmonic metamaterials with deep spatial modulation of optical properties. This work was supported by the Russian Science Foundation (RSF) under project No. 18-79-10262.

Resume : Bicontinuous interfacially jammed emulsion gels (?bijels?) are attractive due to their large interfacial area and interconnected channels for potential applications. Bijels can be used as templates to produce bicontinuous structures. For example, bijels-derived structures may form new hybrid solid electrolytes that consist of a continuous conducting phase and a continuous insulating phase. These electrolytes can have high conductivity. A major obstacle for wide applications of bijels and bijels-derived structures is difficulties in making bijels. In this study, a new method that can make large-size 3D bijels was developed. A ternary liquid mixture was made first by adding ethanol, diethylphthalate (DEP), deionized water, Ludox TMA and CTAB in ethanol. It was stirred vigorously and then stood for 12 hours to firm bijels. Confocal microscopy revealed the bicontinuous structure of bijels, which could be maintained for over 30 days at room temperature. By varying CTAB concentration, the domain size of bijels was changed. To explore the technique, we used hexanedioldiacrylate (HDA) and photo-initiator to replace DEP to generate solid structures. For HDA-based bijels, a UV light was applied to cure HDA. Freeze-drying then evaporated aqueous phase. The bicontinuous structure was clearly seen under SEM and interconnected channels were present. The new bijels fabrication method can lead to large exploration of bijels and bijels-derived structures for many applications.

Resume : In the last years, 3D Printing (3DP) is increasing its importance both in science and in industrial applications due to the peculiar properties and manifolds advantages that the technologies that are included under this umbrella terms can offer.[1] Without going into details for each technology, it is implied the possibility to produce components with shapes impossible to obtain by classical subtractive manufacturing, saving at the same time both raw materials and energy.[2, 3]. Among polymeric 3D printing processes, light-based technologies (SLA and DLP) are generally known for being the fastest and most precise. However their main drawback consists in the limited palette of available printable materials, which restrict the possible applications. Aiming to widen the range of printable materials for DLP, here we will show different strategies for producing 3D printable nanocomposites developed in our laboratories. The idea beyond consists in imparting improved mechanical properties or new functionalities to the printed objects maintaining at the same time a good printability. In this context we will show that a classical direct dispersion of fillers in a photocurable formulation followed by the optimization of printing parameters ( what we call ?the materials? engineering approach?)[4, 5] could be overcome by an appropriate design of the photocurable mixture, adding a bit of materials? science and chemistry. This allows to obtain objects with peculiar properties saving a high printability.[6-8] References: 1. T.A. Campbell, O.S. Ivanova, 3D printing of multifunctional nanocomposites, Nano Today, 2013, Vol. 8, 119-120. 2. F.P.W. Melchels, J. Feijen, D.W. Grijpma, A review on stereolithography and its applications in biomedical engineering, Biomaterials, 2010, Vol. 31, 6121-6130. 3. R.D. Farahani, M. Dubé, D. Therriault, Three-Dimensional printing of multifunctional nanocomposites: manufacturing techniques and applications, Advanced Materials, 2016, Vol. 28, 5794-5821. 4. G. Gonzalez, A. Chiappone, I. Roppolo, E Fantino, V. Bertana, F. Perrucci, L. Scaltrito, F. Pirri, M. Sangermano; Development of 3D printable formulations containing CNT with enhanced electrical properties, Polymer, 2017, vol. 109, pp. 246-253 5. A. Chiappone, I. Roppolo, E. Naretto, E. Fantino, F. Calignano, M. Sangermano, C.F. Pirri; Study of graphene oxide-based 3D printable composites: Effect of the in situ reduction, Composite Part B: Engineering, 2017, Vol 124, pp 9-15. 6 J.Wang, A. Chiappone, I. Roppolo,F. Shao, E. Fantino, M. Lorusso, D. Rentsch, K. Dietliker, C.F. Pirri, H. Grützmacher; All-in-One Cellulose Nanocrystals for 3D Printing of Nanocomposite Hydrogels, Angewandte Chemie International Edition, 2018, vol 57, pp 2353-2356 7 E. Fantino, A. Chiappone, I. Roppolo, D. Manfredi, R.M. Bongiovanni, C. Pirri, F. Calignano; 3D Printing of Conductive Complex Structures with In Situ Generation of Silver Nanoparticles. Advanced Materials 2016, vol. 28, pp. 3712-3717 8. A. Chiappone, E. Fantino, I. Roppolo, M. Lorusso, D. Manfredi, P. Fino, C. Pirri, F. Calignano; 3D Printed PEG-Based Hybrid Nanocomposites Obtained by Sol?Gel Technique. ACS Applied Materials & Interfaces Vol. 8, pp. 5627-5633

Resume : Plasmonic nanoparticles have intriguing properties that can be used as building blocks for optical metamaterials, in photocatalysis, for medical treatments and sensing applications. To fabricate devices based on plasmonic nanoparticles methods such as nanolithography are widely employed, which unduly increases fabrication cost and stands in the way of a cost efficient and scalable technology. In this contribution I will present our efforts to process plasmonic devices in a radically different way. Specifically, we chose to embed gold or palladium nanoparticles, synthesized via wet-chemistry, in a thermoplastic polymer matrix, thus creating plastic-plasmonic hybrid materials. These composites can be readily extruded into filaments. 3D printing using fused filament fabrication, a widely used additive manufacturing technique, then allowed us to realize macroscopic plasmon-active objects with a large variety of shapes and architectures. Among them, we were able to fabricate 3D-printed optical plasmonic hydrogen sensors with remarkable response times, ranging from seconds to minutes depending on the dimensions and nanoparticle stoichiometry, and with intrinsic resistance towards deactivation of carbon monoxide. Evidently, 3D printing is a viable approach for fabrication of more cost-efficient and scalable plasmonic devices.

Resume : Recently, polymeric soft-actuators activated by magnetic fields are gaining more and more interest. By coupling flexible polymeric matrices and magnetization it is possible to fabricate objects which undergo large deformations under low applied forces, and their movements can be remotely controlled. Digital Light Processing (DLP), a photoinduced 3D printing technique looks very advantageous for the production of these devices. In fact, it is possible to take advantage of the fast polymerization kinetics of the photopolymerization, together with the easy dispersion of magnetic fillers in liquid resins, which can undergo to a self-assembly process when exposed to external magnetic fields. It is thus possible to build polymeric nano-composite materials where the magnetic self-assembled chains constitute the programmed hierarchal microstructures. In this work, we dispersed magnetite (Fe3O4) nanoparticles (NPs) in a urethane-acrylic formulation (Ebecryl 8232, Allnex) suitable for DLP process. The formulations were then exposed to external magnetic fields, investigating the evolution of the microstructure. Several parameters as magnetic field intensity, magnetization time, and system viscosity were studied in relation to the average length, and length-distribution of the formed Fe3O4 chains. The influence of a reactive diluent (BA) on the flexibility of the material was evaluated as well as the influence of Fe3O4 NPs in photopolymerization kinetics. Once defined the best conditions, formulations were 3D-printed by a DLP equipment: complex shape objects were produced, and their response to external magnetic stimuli was investigated, together with their mechanical and thermal characteristics.

Resume : At present study, the possibility of controlling the morphology, shape and porosity of ceramic-polymer matrix (CPM) based on a polymer with the addition of nano titanium dioxide (TiO2) during powder bed fusion process was shown. We have experimentally determined the optimal regimes for layerwise laser melting. The 3D parts were obtained from polycarbonate + nano-titania powder compositions with 10: 1 and 5: 1 (by vol.) ratio. The geometric and microstructural features of the created 3D samples by the methods of linear measurements of transverse dimensions, optical microscopy (OM) and x-ray analysis were evaluated. The OM indicates a heterogeneous distribution of nano-titania in the polymer matrix. The XRD patterns showed the presence of the initial phase (TiO2) without significant changes, which is useful for plasmonic applications. Additional thermal heating near 30 min of 3D parts in the oven in the range of 150?400 degrees revealed conditions for changing the porosity of the CPM, removing the polymer binder and titania framework fixing. With the CPM porosity decrease, the diffusion coefficient of electrons in TiO2 increases, which leads to an increase in the density of the generated current and the efficiency of solar cells.

Resume : 3D additive manufacturing has shown significant promise in fabricating customized complex structures for bioelectronic applications. Mechanical flexibility is a highly critical feature for bioelectronic devices which are in direct contact with biological tissues. Thermally conductive polymer nanocomposites with high cytocompatibility are required to meet the requirements of complex 3D architectures for use in bioelectronics. This study investigates the 3D printability of highly flexible, thermal conductive and biocompatible boron nitride (BN) thermoplastic polyurethane (PU) nanocomposites. BN nanoparticles, a ceramic additive with high thermal conductive and electrical insulating properties, were added to the PU in order to manage heat transfer. The BN-PU nanocomposites exhibited acceptable mechanical and highly thixotropic properties that make them as favorable candidates for extrusion-based 3D printing. Flexible structures of BN-PU nanocomposites were 3D printed using a pneumatic-based 3D printer. The thermal conductivity of nanocomposites was increased by more than 50% at loadings of up to 20 wt% of BN. This work demonstrates the potential applications of the BN-PU nanocomposite as a biocompatible material in bioelectronic devices.