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The manufacturing of non-woven fibrous composites by electrospinning is being spread in catalysis, adsorption and water purification applications. Specifically designed fillers are required to boost the performances of such electrospun materials and achieve additional functionalities. Herein, silica nanoparticles (SiO 2 NP) and TiO 2 -acetylacetonate (TiO 2 acac, hybrid titania) microparticles (up to 90 μm) were synthesized by the sol-gel route and electrospun with poly(vinylpyrrolidone) (PVP) to obtain ternary composite mats. Different amount of hybrid titania microparticles was used to study its influence on the electrospinning performance. Analysis of ternary composite mats by spectroscopy (FTIR, EPR) and microscopy (SEM, TEM) confirmed the successful inclusion of large TiO 2 acac microparticles into the nanofiber matrix. Surface charge was measured by Zeta potential to evaluate the effect of hybrid titania on the surface chemistry of the composite mats. EPR analysis proved the presence of stable superoxide radicals on the ternary mat generated by TiO 2 acac microparticles. The silica backbone of the fibers allowed to achieve water-resistance, whereas the surface-stabilized superoxide radicals guaranteed oxidative degradation activity even under dark. This led to enhanced removal of methylene blue, with an initial rate ∼70% higher compared to a binary composite mat containing only SiO 2 NP as filler. This preliminary study highlights the possible application of PVP/SiO 2 NP/TiO 2 acac mats as promising membranes for oxidation processes. [Display omitted] • PVP-based ternary composite fibers were prepared by eco-friendly electrospinning technique. • Hybrid titania microparticles (up to 90 μm) suspensions were successfully electrospun. • Adsorbed superoxide radicals on electrospun mats surface proved by EPR analysis. • Potential oxidative adsorption/degradation of water pollutants in absence of light irradiation. [ABSTRACT FROM AUTHOR]

Abstract: A large number of recent literature data focus on modification/modulation of surface chemistry of inorganic materials in order to improve their functional properties. Melanins, a wide class of natural pigments, are recently emerging as a powerful organic component for developing bioinspired active material for a large number of applications from organoelectronics to bioactive compounds. Here we report the use of the approach referred as “chimie douce”, involving in situ formation of the hybrids through reactions of precursors under mild conditions, to prepare novel hybrid functional architectures based on eumelanin like 5,6 dihydroxyindole-2-carboxylic acid (DHICA) polymer and TiO2. Two synthesis procedures were carried out to get DHICA-melanin coated TiO2 nanoparticles as well as mixed DHICA/TiO2 hybrid nanostructures. Such systems were characterized through EPR, FT-IR and fluorescence spectroscopy, thermogravimetric analysis (TGA), X-ray diffraction (XRD), and TEM microscopy in order to assess the effect of synthesis path as well as of DHICA content on structural, morphological and optical properties of TiO2 nanostructures. In particular, EPR, FT-IR spectra and TGA analysis confirmed the presence of DHICA-melanin in these samples. TEM measurements indicated the formation of the nanoparticles having relatively narrow size distribution with average particle size of about 10nm. DHICA-melanin does act as a morphological agent affecting morphology of hybrid nanostructures. XRD analysis proved that TiO2 hybrid nanoparticles kept anatase structures for DHICA-melanin contents within the range of investigated compositions, i.e. up to 50% wt/wt. [Copyright &y& Elsevier]

Abstract: We report on a facile method towards a synthesis of novel hybrid heparin silica nanoparticles involving a modification of the Stober method. Tetrapropyl orthosilicate (TPOS) was used instead of the traditional TEOS or TMOS; by this way we could overcome the solubility problems of heparin in ethanol and exploit the good solubility of heparin in proper isopropanol–water mixtures. Aminopropyl triethoxysilane (APTS) was also used to have a good link of heparin to silica particles. SEM, DLS, FTIR and NMR proved that we did find conditions in which heparin conjugated silica particles were produced. Thermogravimetry allowed to evaluate the heparin/silica weight ratio to be 0.61. The efficiency of heparin binding to the particles was appreciated to be 35wt.%. [Copyright &y& Elsevier]

• Polymeric sound absorbers can be produced through electrospinning, materials with a fiber diameter from few nanometers to several micrometers. • A numerical simulation model of the acoustic behavior of poly vinyl pyrrolidone/silica composites were developed. • The results of the measurements of the sound absorption coefficient were analyzed. • The results of the numerical modeling of the acoustic coefficient were reported. • The neural network-based model showed high Pearson correlation coefficient values (0.942), indicating many correct predictions. Polymeric sound absorbers can be produced through electrospinning, a process which allows to fabricate high specific surface materials with a fiber diameter from few nanometers to several micrometers. In this study, a numerical simulation model of the acoustic behavior of poly vinyl pyrrolidone/silica composites were developed. First, the characteristics of the poly vinyl pyrrolidone/silica composites were examined, and the manufacturing of the material were described. Subsequently, the results of the measurements of the sound absorption coefficient were analyzed. Finally, the results of the numerical modeling of the acoustic coefficient were reported. The neural network-based model showed high Pearson correlation coefficient values (0.942), indicating many correct predictions. Taking into account the bell shaped acoustic response of the studied blankets as a function of frequency, the possibility to foresee the needed mass with the neural network-based model will be of great value for the applications where high acoustic absorption is required in specific limited frequency ranges. [ABSTRACT FROM AUTHOR]

The effect of the addition of additives such as melamine (Mel), silica nanoparticles and a phosphorus-based compound, i.e. 3-(6-oxidodibenzo[c,e][1,2]oxaphosphinin-6-yl)propenamide (DA), on the fire and mechanical performance of a bisphenol A diglycidyl ether (DGEBA)-based epoxy resin cured with isophoronediamine has been investigated. A UL 94-V0 classification was achieved for epoxy resin containing DA at 2 wt% of phosphorus loading. However, addition of silica nano particles was necessary to avoid melt dripping. The incorporation of DA and Mel to the epoxy resin promoted a remarkable reduction (48% to 70%) in the heat release rate (HRR) values, a significant delay (up to 47%) in the ignition time in cone calorimetry experiments, and thus an increase (~75%) in the time to flashover. Evolved gas, thermal and fire analysis was used to propose the combined mode of action of DA, Mel and silica in the fire performance improvement of the epoxy system. Tensile and three-point bending flexural tests showed that the addition of DA increases the rigidity of the resin, resulting in a strong increase in the Young's modulus (up to 34%) and in a slight reduction in fracture strength, elongation break and toughness which is typical for non-reactive additives. Unlabelled Image • Self-extinguishing epoxy-silica nanocomposite at very low phosphorus loadings. • In-situ sol-gel silica in the epoxy system prevented melt dripping. • Intumescent system achieved significant reduction in heat release rate (~70%) and delay of the ignition time (~50%). [ABSTRACT FROM AUTHOR]