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• great reactivity of montmorillonite (oMMT) in presence of phosphates. • formation of different Al-O-P and Si-O-P compounds. • mechanism of fire behaviour occurred in the condensed phase. • formation of a charred structure that reduced the fuel production. In the first part of this work, novel elastomeric panels with paraffin for thermal energy storage applications were developed. Ethylene-Propylene Diene Monomer (EPDM) rubber filled with a shape-stabilized paraffin, as phase change material with a melting temperature of 28 °C, was covered with a nitrile-butadiene rubber (NBR) envelope. In order to improve the fire resistance, two selected flame retardants (FRs) were dispersed both in the EPDM core and in the NBR envelope. In this work, the combustion residues from cone calorimeter tests were analysed by various techniques to explain the combustion mechanisms and the interaction of FRs. Nuclear magnetic resonance (NMR) evidenced the complexity of the system, characterized by the formation of char, by the reactivity of organomodified montmorillonite (oMMT) in presence of phosphates and structural rearrangements of the inorganic components. The use of a flame retardant based on ammonium polyphosphate and synergistic agents (based on phosphorus) led to formation of different Al-O-P and Si-O-P compounds. The X-ray diffraction (XRD) analysis highlighted that the formation of silicon phosphate, from the reaction of ammonium polyphosphate and oMMT, was possible only at high phosphorus contents. From the phosphorus content detected through energy dispersive X-ray spectroscopy (EDX) it was possible to indicate that the phosphorus remained in the condensed phase during the combustion. [ABSTRACT FROM AUTHOR]

Sodium montmorillonite/organosilica sol-gel coatings were obtained from a hydrolysed solution of 3-glycidoxypropyltrimethoxysilane (GPTMS), methyltriethoxysilane (MTES) and tetraethoxysilane (TEOS) with 2 wt% of sonicated sodium montmorillonite (Mt). The effect of different sonication times (0, 1, 3, 12 h) on the structure of both Mt and sol-gel clay-organosilica nanocomposites was investigated by means of 29 Si and 27 Al solid state nuclear magnetic resonance (NMR) and X-ray diffraction (XRD). Mt underwent relevant structural changes with the sonication treatment and the effect appeared time-dependent, although not linear. The structural changes induced on clay by the sonication process were kept in the clay-organosilica nanocomposite, according to 29 Si NMR. Mt addition to the hybrid sol-gel network led to decreasing the amount of completely condensed silicon units by formation of new Si-O-Al hetero-metallic bonds, as shown by 27 Al NMR results. Moreover, organosilica matrix and Mt appeared to interact even in the absence of the sonication treatment of the filler. The NMR study of GPTMS/MTES/Mt and TEOS/Mt samples clearly proves the interaction of Mt with the silsesquioxane (T) species in the obtained composites. [ABSTRACT FROM AUTHOR]

In this work, organosilane-derived sol-gel films containing different amounts of cerium ions applied on AA 1050 were investigated. The sol-gel coatings were prepared from 3-glycidoxypropyltrimethoxysilane (GPTMS) and methyltriethoxysilane (MTES) mixtures with the addition of cerium nitrate in order to achieve different concentrations of Ce ions (from 10 −5 M to 10 −2 M). The effect of the cerium load on the structure of the cured sol-gel films was investigated by means of solid state NMR and FT-IR spectroscopy. The corrosion protection properties of the different sol-gel layers were investigated mainly by means potentiodynamic curves and electrochemical impedance spectroscopy (EIS). FT-IR and solid state NMR suggested a significant influence of the Ce cations on the network structure: not only the degree of condensation decreases with Ce addition but also the structural modification of the silsesquioxane network is observed with preferential formation of ladder-like species for low Ce 3+ content and cages predominance for Ce/Si molar ratio greater than 0.039, i.e. [Ce 3+ ] = 1·10 −4 M. Electrochemical tests revealed that the effect of Ce ions on the structure of the coatings does not lead to remarkable changes in the barrier properties. Moreover, it was found that the Ce ions seems to be present in the cured films and are able to migrate towards the metal/coating interface thus providing a stabilization of the metal interface. [ABSTRACT FROM AUTHOR]

Organic-inorganic hybrids (OIHs) are a type of material that can be obtained using the sol-gel process and has the advantages of organic and inorganic moieties in a single material. Polyetheramines have been widely used in the preparation of this type of material, particularly in combination with epoxy-based alkoxysilanes. Nevertheless, epoxyciclohexylethyltrimethoxysilane (ECHETMS) is a promising alkoxysilane with an epoxy terminal group that is quite unexplored. In this work, four novel OIH materials were synthesized using the sol-gel method. The OIHs were based on Jeffamines® of different molecular weights (D-230, D-400, ED-600, and ED-900), together with ECHETMS. The materials were characterized using multinuclear solid state NMR, FTIR, BET, UV/Vis spectroscopy, EIS, and TGA. The influence of the Jeffamine molecular weight and the suitability of these materials to act as a supporting matrix for heteroaromatic probes were assessed and discussed. The materials show interesting properties in order to be applied in a wide range of sensing applications. [ABSTRACT FROM AUTHOR]

Hybrid sol-gel coatings, named U(X):TEOS, based on ureasilicate matrices (U(X)) enriched with tetraethoxysilane (TEOS), were synthesized. The influence of TEOS addition was studied on both the structure of the hybrid sol-gel films as well as on the electrochemical properties. The effect of TEOS on the structure of the hybrid sol-gel films was investigated by solid state Nuclear Magnetic Resonance. The dielectric properties of the different materials were investigated by electrochemical impedance spectroscopy. The corrosion behavior of the hybrid coatings on HDGS was studied in chloride-contaminated simulated concrete pore solutions (SCPS) by polarization resistance measurements. The roughness of the HDGS coated with hybrids was also characterized by atomic force microscopy. The structural characterization of the hybrid materials proved the effective reaction between Jeffamine® and 3-isocyanate propyltriethoxysilane (ICPTES) and indicated that the addition of TEOS does not seem to affect the organic structure or to increase the degree of condensation of the hybrid materials. Despite the apparent lack of influence on the hybrids architecture, the polarization resistance measurements confirmed that TEOS addition improves the corrosion resistance of the hybrid coatings (U(X):TEOS) in chloride-contaminated SCPS when compared to samples prepared without any TEOS (U(X)). This behavior could be related to the decrease in roughness of the hybrid coatings (due TEOS addition) and to the different metal coating interaction resulting from the increase of the inorganic component in the hybrid matrix. [ABSTRACT FROM AUTHOR]

Thiol-functionalized nanobuilding blocks (NBBs) were synthesized from 3-mercaptopropyltrimethoxysilane by using the in situ water production (ISWP) process in which the water needed to hydrolyze the precursor was provided by means of an esterification reaction. In the present study the reaction between 1-propanol and chloroacetic acid was used. Whereas the growth of the Si oligomers was followed at room temperature and 100 °C using 1D 29Si and 2D 1H-29Si heteronuclear single quantum correlation (HSQC) NMR spectroscopic experiments, the amount of water delivered along the process was followed by means of 1H NMR spectroscopy. The results show a good correlation between the evolution of the degree of condensation and the amount of water produced in situ. They also point to the preferential formation of cagelike structures and the narrowing of the species distribution over long reaction times. The average size of the growing oligomers was estimated from their diffusion coefficient, which was measured by means of 1H diffusion-ordered NMR spectroscopy (DOSY NMR). Like gel permeation chromatography, DOSY NNR showed a plateau between 70 to 100 hours in the growth of the oligomers, a time at which, according to 29Si NMR spectroscopy, the well-defined octakis(3-mercaptopropylsilsesquioxane) is the major species. [ABSTRACT FROM AUTHOR]

13 C nuclear magnetic resonance and mid-infrared spectroscopies were used for characterizing changes in the chemical structure of wood polymers (cellulose, hemicellulose and lignin) in relation to the tree growth location. Samples of three provenances in Europe (Finland, Poland and Italy) were selected for studies. The requirement was to use untreated solid wood samples to minimize any manipulation to the nanostructure of native wood. The results confirm that the chemical and physical properties of samples belonging to the same wood species ( Picea abies Karst.) differ due to the origin. Both FT-IR and dynamic NMR spectroscopies were able to correctly discriminate samples originating from three different provenances in Europe. Such methods might be very useful for both, research and understanding of wood microstructure and its variability due to the growth conditions. [ABSTRACT FROM AUTHOR]

Hybrid organic-inorganic sol-gel derived coatings have been prepared by dip coating on glass substrates from alcoholic solutions of tetraethoxysilane (TEOS), methyltriethoxysilane (MTES), 3-aminopropyltriethoxysilane (APTES), 3-glycidoxypropyltrimethoxysilane (GPTMS) and phenyltriethoxysilane (PhTES). The hybrid materials have been fully characterized by means of solid state NMR spectroscopy and X-ray diffraction. The degree of cross-linking and the extent of interaction between silica and silsesquioxane phases appear dependent on the ratio between TEOS and organotrialkoxysilane and on the chemical features of the organic function linked to silicon, and influence the sorption ability towards aromatic compounds of hybrid films. The hybrid coatings have been put into an optical-grade quartz chamber placed into a UV-VIS-NIR spectrophotometer and the organic compounds have been allowed flowing through the chamber recording of molecule absorption spectra vs. time. Absorbance curves vs. time have also been collected at a fixed wavelength for different molecule-coating couples and simple kinetic models have been used for comparing the adsorption capability of the different films, which has been related to the chemical interactions between molecules and coatings. [ABSTRACT FROM AUTHOR]

A homogeneous, though multifaceted, secondary metabolic character emerges from a detailed investigation of secondary metabolites produced by the ciliate species Euplotes rariseta. In particular, from the strain NZ2, collected in New Zealand (Omaha Bay), two new irregular diterpenoids, omaholidenol ( 6) and omaholidenal ( 7), have been isolated which are the C5 homologues of rarisetenolide ( 1), the latter being previously found as the main secondary metabolite in different strains of the same species. On the other hand, from strain Ubt22, three new diterpenoids, ubatubaolidenal ( 8), ubatubadial A ( 9), and ubatubadial B ( 10), have been found. Finally, two new diterpenoids, epoxyfocardolide ( 11) and prenyl epoxyrarisetenolde ( 12), were isolated in low yields from the sister species Euplotes quinquecarinatus and Euplotes parkei, respectively. All these findings strongly suggest, in addition to a wide chemical polymorphism in E. rariseta populations, a close parallelism between the production pattern of secondary metabolites and the phylogenetic relationships of the species, confirming the chemotaxonomic utility of these compounds in the ciliate genus Euplotes. [ABSTRACT FROM AUTHOR]

Abstract: TiO2–SiO2 composite materials with photocatalytic properties similar to those of slurry powdered TiO2 is obtained by a novel sol–gel synthetic strategy involving the hydrolysis/condensation of TMOS assisted by PEG as templating agent and the grafting of preformed titania nanocrystals onto the macropore walls of the silica matrix. In order to anchor TiO2 particles to the surface of SiO2, avoiding their embedding into silica matrix, functionalization with carboxylic acid or amine derivatives was carried out. The functionalization induces the confinement of titania nanocrystals in PEG, during the silica formation, and allows their dispersion on the silica surface. TiO2–SiO2 materials exhibit high thermal and chemical stability and a photocatalytic activity in the phenol mineralization comparable to that of powder TiO2 in slurry (half degradation time ∼120min). These results suggest that the immobilization procedure here reported provides high accessibility of the catalyst active sites preserving the functional properties of the photoactive catalyst. [Copyright &y& Elsevier]

We show that thin films of silica loaded with 22 wt% of carbon nanotubes (CNTs) can be deposited on cellulose substrate via the sol–gel route by a well-controlled process. The high loadings are obtained by airbrush spraying of a diluted sol solution (which contained a much smaller concentration of CNTs) followed by drying at 200 °C. The films are nearly continuous despite the fibrous structure of the substrate. The high degree of connectivity of the stranded structure of the CNTs yields a specific electrical conductivity of 3 × 103 Ω−1 m−1. In contrast, films made with high loadings of carbon black have poor electrical conductivity. Results from mechanical tensile tests of samples are also reported. This economical method of producing CNT dispersed thin films could find application in catalysis, as electrodes in fuel cells and batteries, and in sensor technologies. [ABSTRACT FROM AUTHOR]

Abstract: SnO2 and SnO2 +Co-porphyrin solids were prepared from SnCl4 in propanol and hydrolyzed to sol. Thermal behavior of samples obtained at 110°C was studied in the 20–600°C interval by thermal analysis coupled with mass spectrometry for identification of released species. The original samples maintain residual Sn–OR, Sn–OH and Sn–Cl groups up to 350°C. The sample doped with 1% Co-porphyrin differs for a significant presence of residual Sn–Cl species, accounting for SnCl4 release in the 300–340°C range. 119Sn solid state NMR analysis reveals disordered SnO2 species in the sample heated at 250°C and non-uniform SnO6 units in the SnO2 +Co-porphyrin sample at 110°C, due to persistence of Sn–OR and Sn–OH groups. This complexity is lost at 250°C. X-ray diffraction analysis confirms all these data. The sensing efficiency of these materials versus alcohols is ascribed to the presence of an open, incomplete SnO2 structure, which is more pronounced in the Co-porphyrin-doped sample. [Copyright &y& Elsevier]

Barium titanate (BT) recently gained new interest in the preparation of dielectric and piezoelectric lead-free materials for applications in sensors, electronics, energy harvesting and storage fields. Barium titanate nanocomposites can achieve attractive performance, provided that the compatibility between ceramic particles and polymeric matrices is enhanced to the benefit of the physical properties of the final composite. Tuning the particle–matrix interface through particle functionalization represents a viable solution. In this work, surface functionalization of BT nanoparticles (NPs), obtained by hydrothermal synthesis, with 3-glycidyloxypropyltrimethoxysilane, 2-[(acetoxy(polyethyleneoxy)propyl]triethoxysilane and triethoxysilylpropoxy(polyethyleneoxy)dodecanoate, was performed after optimizing the hydroxylation process of the NPs to improve their surface reactivity and increase the yield of grafting. Solid-state nuclear magnetic resonance and thermogravimetric analysis were used to quantify the molecules grafted onto the ceramic nanoparticles. Both bare and functionalized particles were employed in the realization of epoxy- and polydimethylsiloxane (PDMS)-based nanocomposites. Functionalization was proven to be beneficial for particle dispersibility and effective for particle alignment in the PDMS matrix. Moreover, the dielectric constant measurements revealed the potential of PDMS-based nanocomposites for applications in the field of dielectric elastomers. [ABSTRACT FROM AUTHOR]

The present study reports on the development of a new binary filler system for rubber composites, SiO2@Al2O3, where Al2O3 sheets are grown onto SiO2 nanoparticles aggregates by a sustainable water‐based soft‐chemistry approach. The aim is to synergistically integrate the intrinsic thermal conductivity properties of Al2O3 with the peculiar reinforcement ability of SiO2 in an easy one‐pot solution, which has been exploited to prepare polybutadiene (PB) model composites by a simple solvent casting technique. More in detail, the binary filler was used as‐prepared or suitably surface functionalized with 3‐(Trimethoxysilyl)propylmethacrylate (TMSPM). The filler compatibilization and interplay with the polymeric matrix have been inspected by solid state NMR in conjunction with scanning electron microscopy. These investigations highlighted that the presence of alumina in the binary filler does not undermine the capability of silica in generating polymer chains stiffening and indicated a significant effect of the silanization in providing better filler networking and interaction with the PB host ensuring, in principle, an enhanced thermal transport. Accordingly, thermal conductivity measurements revealed that SiO2@Al2O3 introduction in PB induces a remarkable upgrade of the heat transfer, which becomes much more relevant upon surface modification with TMSPM. These results appear encouraging, paving the possibility of applying SiO2@Al2O3 model system to more complex case studies, where both improved thermal conductivity and enhanced reinforcement are required, such as tires tread formulations. Highlights: A new SiO2@Al2O3 binary filler system was proposed following a soft‐chemistry approach.The binary filler was functionalized to enhance its compatibilization.Fillers were dispersed in polybutadiene by a simple solvent casting technique.Thermal conductivity measurements revealed a remarkable upgrade of the heat transfer ability. [ABSTRACT FROM AUTHOR]

Lanthanoid cations are commonly employed as active corrosion inhibiting agents inside sol-gel coatings derived from organosilanes. However, the effect of lanthanoids on the structure of sol-gel coatings derived from organoalkoxysilanes is still not completely clear and object of debate. Even if it has been reported that lanthanoid ions have a beneficial effect in terms of corrosion protection properties, it has not been completely understood if it is related to the active inhibition of the local electrochemical activity or to a modification of the sol-gel coating structure. In addition, it is still not clear how the lanthanoid ions are distributed in. In order to get some insights into the effect of lanthanoids on the structural and electrochemical properties of sol-gel layers, the present work employs gadolinium ions. Gd was selected also for its magnetic and electronic properties, which strongly affects the signals intensity of many spectroscopy techniques. Accordingly, Gd ions act as a marker to evaluate the localization of lanthanoids in the hybrid network. The structural effect on the sol-gel films promoted by the addition of gadolinium ions has been assessed by means of solid state nuclear magnetic resonance (NMR), Fourier transform infrared (FT-IR) spectroscopy and electron spin resonance (ESR) spectroscopy. The structural features of the Gd-doped coatings have been correlated with their electrochemical response obtained by means of polarization curves and electrochemical impedance spectroscopy (EIS). Image 1 [ABSTRACT FROM AUTHOR]

The functional properties displayed by graphene oxide (GO)-polymer nanocomposites are strongly affected by the dispersion ability of GO sheets in the polymeric matrix, which can be largely improved by functionalization with organosilanes. The grafting to GO of organosilanes with the general formula RSi(OCH3)3 is generally explained by the condensation reactions of silanols with GO reactive groups. In this study, the influence of the organic group on the RSi(OCH3)3 grafting ability was analyzed in depth, taking into account the interactions of the R end chain group with GO oxidized groups. Model systems composed of commercial graphene oxide reacted with 3-aminopropyltrimethoxysilane (APTMS), 3-mercaptopropyltrimethoxysilane (MPTMS), and 3-methacryloxypropyltrimethoxysilane, (MaPTMS), respectively, were characterized by natural abundance 13C, 15N and 29Si solid state nuclear magnetic resonance (NMR), x-ray diffraction (XRD), and electron spin resonance (ESR). The silane organic tail significantly impacts the grafting, both in terms of the degree of functionalization and direct interaction with GO reactive sites. Both the NMR and XRD proved that this is particularly relevant for APTMS and to a lower extent for MPTMS. Moreover, the epoxy functional groups on the GO sheets appeared to be the preferential anchoring sites for the silane condensation reaction. The characterization approach was applied to the GO samples prepared by the nitric acid etching of graphene and functionalized with the same organosilanes, which were used as a filler in acrylic coatings obtained by cataphoresis, making it possible to correlate the structural properties and the corrosion protection ability of the layers. [ABSTRACT FROM AUTHOR]

NiO-based films and nanostructured materials have received increasing attention for a variety of technological applications. Among the possible strategies for their fabrication, atomic layer deposition (ALD) and chemical vapor deposition (CVD), featuring manifold advantages of technological interest, represent appealing molecule-to-material routes for which a rational precursor design is a critical step. In this context, the present study is focused on the coordination sphere engineering of three heteroleptic Ni(II) β-diketonate–diamine adducts of general formula [NiL2TMEDA] [L = 1,1,1-trifluoro-2,4-pentanedionate (tfa), 2,2-dimethyl-6,6,7,7,8,8,8-heptafluoro-3,5-octanedionate (fod) or 2,2,6,6-tetramethyl-3,5-heptanedionate (thd), and TMEDA = N,N,N′,N′-tetramethylethylenediamine]. Controlled variations in the diketonate structure are pursued to investigate the influence of steric hindrance and fluorination degree on the chemico-physical characteristics of the compounds. A multi-technique investigation supported by density functional calculations highlights that all complexes are air-insensitive and monomeric and that their thermal properties and fragmentation patterns are directly dependent on functional groups in the diketonate ligands. Preliminary thermal CVD experiments demonstrate the precursors' suitability for the obtainment of NiO films endowed with flat and homogeneous surfaces, paving the way to future implementation for CVD end-uses. [ABSTRACT FROM AUTHOR]

The interaction between activators (ZnO) and co-activators (stearic acid, SA) represents a key step in the vulcanization process, to generate Zn(II) intermediate complexes that enhance the reaction kinetic and promote the shortening of sulfur bridges, leading to highly cross-linked materials. To understand the influence of the structural, morphological and surface properties of ZnO in the reactivity with SA, in this work, pure ZnO nanoparticles (NPs) and ZnO NPs anchored on SiO 2 (ZnO/SiO 2) were prepared through soft chemistry techniques. Tailoring of morphology and surface features was accomplished through a fine control of the synthetic parameters, as demonstrated by the careful characterization of the activators. Then, the interaction of pure ZnO and ZnO/SiO 2 activators with SA in the absence of rubber was investigated by using Differential Scanning Calorimetry (DSC). The occurrence of Zn(II)-SA complexes with different thermal stability and structural properties was assessed by a comprehensive thermogravimetric and spectroscopic survey. The generation and the chemical structure of these specific vulcanization intermediates was related to the peculiar characteristics of the ZnO/SiO 2 systems and, in turn, to their ability in imparting faster kinetics and higher curing efficiency to isoprene rubber nanocomposites, compared to bare ZnO. These results, besides proposing a valid benchmark for achieving further insights on the interaction of stearic acid with activators, pave the way to provide specific protocols for a better design and implementation of ZnO-based materials able to effectively enhance the rubber vulcanization process, with significant economic and environmental advantages. [ABSTRACT FROM AUTHOR]

The development of advanced polymer nanocomposites requires a strong filler-polymer interfacial interaction and an optimal filler nanodispersion. The incorporation of the clays into a polymer matrix frequently does not improve the composite mechanical properties, owing to both poor dispersion and macroscopic particle dimensions. In this work, pristine and organically-modified sepiolites (Sep) were structurally modified by an acid treatment, which provides nano-sized sepiolite (NS-Sep) fibers with reduced particle size and increased silanol groups on the surface layer. NS-Sep fibers were used to prepare styrene-butadiene rubber nanocomposites with enhanced mechanical properties. Dynamic-mechanical analysis of clay polymer nanocomposites demonstrated that the NS-Sep fibers provided an excellent balance between reinforcing and hysteretic behavior, compared to the large-sized pristine Sep and isotropic silica. This was related to the enhanced interfacial chemical interaction between NS-Sep and rubber, as well as to the size and self-assembly of anisotropic nanofibers to form filler network structures, as supported by transmission electron microscopy analysis. The preparation of nanocomposites, based on Sep nanofibers obtained by a simple and versatile acid treatment, can thus be considered an alternative approach for the designing of advanced clay polymer nanocomposites. [ABSTRACT FROM AUTHOR]

The hydrolysis-condensation of trialkoxysilanes under strictly controlled conditions allows the production of silsesquioxanes (SSQs) with tunable size and architecture ranging from ladder to cage-like structures. These nano-objects can serve as building blocks for the preparation of hybrid organic/inorganic materials with selected properties. The SSQs growth can be tuned by simply controlling the reaction duration in the in situ water production route (ISWP), where the kinetics of the esterification reaction between carboxylic acids and alcohols rules out the extent of organosilane hydrolysis-condensation. Tunable SSQs with thiol functionalities (SH-NBBs) are suitable for further modification by exploiting the simple thiol-ene click reaction, thus allowing for modifying the wettability properties of derived coatings. In this paper, coatings were prepared from SH-NBBs with different architecture onto cotton fabrics and paper, and further functionalized with long alkyl chains by means of initiator-free UV-induced thiol-ene coupling with 1-decene (C10) and 1-tetradecene (C14). The coatings appeared to homogeneously cover the natural fibers and imparted a multi-scale roughness that was not affected by the click functionalization step. The two-step functionalization of cotton and paper warrants a stable highly hydrophobic character to the surface of natural materials that, in perspective, suggests a possible application in filtration devices for oil-water separation. Furthermore, the purification of SH-NBBs from ISWP by-products was possible during the coating process, and this step allowed for the fast, initiator-free, click-coupling of purified NBBs with C10 and C14 in solution with a nearly quantitative yield. Therefore, this approach is an alternative route to get sol-gel-derived, ladder-like, and cage-like SSQs functionalized with long alkyl chains. [ABSTRACT FROM AUTHOR]

Sepiolite clay is a natural filler particularly suitable to be used with polysaccharide matrices (e.g., in starch-based bio-nanocomposites), increasing their attractiveness for a wide range of applications, such as packaging. Herein, the effect of the processing (i.e., starch gelatinization, addition of glycerol as plasticizer, casting to obtain films) and of the sepiolite filler amount on the microstructure of starch-based nanocomposites was investigated by SS-NMR (solid-state nuclear magnetic resonance), XRD (X-ray diffraction) and FTIR (Fourier-transform infrared) spectroscopy. Morphology, transparency and thermal stability were then assessed by SEM (scanning electron microscope), TGA (thermogravimetric analysis) and UV–visible spectroscopy. It was demonstrated that the processing method allowed to disrupt the rigid lattice structure of semicrystalline starch and thus obtain amorphous flexible films, with high transparency and good thermal resistance. Moreover, the microstructure of the bio-nanocomposites was found to intrinsically depend on complex interactions among sepiolite, glycerol and starch chains, which are also supposed to affect the final properties of the starch–sepiolite composite materials. [ABSTRACT FROM AUTHOR]

This work investigates the lithium doping effect on the structural and thermal behavior of (Mg 0.2 Co 0.2 Ni 0.2 Cu 0.2 Zn 0.2)O high entropy oxide (HEO) obtained by co-precipitation. The powders are characterized by differential thermal and thermogravimetric analyses (DTA-TG), mass spectroscopy, dilatometry, X-ray diffraction (XRD), magic angle spinning nuclear magnetic resonance (MAS NMR), Raman spectroscopy, X-ray photoelectron spectra (XPS) and electron spin resonance (ESR). The results point out that Co3+ ions (within a spinel phase) are reduced to Co2+ before the formation of the high entropy oxide in the absence of Li. Conversely, no reduction is observed in the case of Li-doping, thus indicating the presence of Co3+ within the high entropy rock salt lattice. At high temperature (>1050–1150 °C), the HEO phase loses oxygen changing the charge compensation mechanism for Li incorporation (mostly based on the presence of 3 + cations and oxygen vacancies at low and high temperatures, respectively). Moreover, it is found that lithium lies in two well-distinct chemical environments in HEO, which cannot be completely explained by assuming a random organization of the high entropy phase. This suggests the existence of some short-range order and possible M3+-Li+ pairs. • Li dissolves into the rock salt HEO phase in substitutional positions. • Single-phase HEO is formed without the Co3+ reduction in the case of Li-doping. • Li sits in two well-distinct chemical environments within the HEO structure. • The presence of some kind of short-range order within the Li-doped HEO is hypothesized. [ABSTRACT FROM AUTHOR]

The first examples of organic-inorganic hybrid materials reinforced by transition-metal oxoclusters that exhibit shape memory properties, based on the covalent incorporation of zirconium-based inorganic building blocks, are reported. Methacrylate-functionalized zirconium oxoclusters Zr4O2(OMc)12 and [Zr6O4(OH)4(OOCCH2CH3)3{OOCC(CH3)=CH2}9]2, with the covalent incorporation in a butyl acrylate (BA)/polycaprolactone dimethacrylate (PCLDMA) copolymer and the noncovalent incorporation of [Zr6O4(OH)4(OOCCH2CH3)12]2 are focused upon herein. Shape recovery and fixity rates are studied to observe if the shape memory properties are preserved upon going from a simple copolymer to noncovalent or covalent-based hybrids. These rates display values higher than 90 %, which provides evidence that the oxocluster does not hinder the shape memory properties in the hybrid materials. The introduction of an inorganic phase and the progressively more stable interactions between organic and inorganic parts lead to an enhancement of the thermomechanical properties. The materials are characterized through FTIR spectroscopy, thermogravimetric analysis, differential scanning calorimetry, and swelling tests. Dynamic-mechanical analyses are used to investigate whether the hybrid materials display thermally activated shape memory properties. The stability of the hybrid materials are evaluated by a combined spectroscopic approach based on FTIR, solid-state NMR, and X-ray absorption spectroscopy. [ABSTRACT FROM AUTHOR]

Abstract: Silsesquioxane nanoparticles were synthesized from organotrialkoxysilanes in ethanol/water medium by a two-step hydrolysis–condensation process. Regular shaped spheres functionalized by vinyl, methyl, ethyl, phenyl, amyl, octyl, 3-aminopropyl groups were obtained, with sizes in the range 100–400nm. The integrity of the organic functional groups and the condensation degree of the silsesquioxane networks were detected by multinuclear solid state Nuclear Magnetic Resonance (NMR). The nanoparticles thermal behavior was studied by thermogravimetric analyses, and N2 sorption was used to measure the particles porosity. Coatings were obtained from particles suspensions by spin coating technique and the surface properties were studied by contact angle measurements. The emission of Rhodamine 6G doped nanoparticles was analyzed in the visible light region. The fluorescence experiments highlight the influence of the different matrices on amount of dye retained into the network and fluorescence intensity. [Copyright &y& Elsevier]

[Display omitted] • O 2 -getter nanomaterials comprised of polybutadiene, TiO 2 and ladder silsesquioxanes. • TiO 2 does not induce major structural modifications within the nanocomposites. • The presence of TiO 2 enhances the O 2 uptake rate up to ca. 70% • Surface modified TiO 2 provides up to 60% higher O 2 uptake rate than bare TiO 2. • TiO 2 induced generation of singlet oxygen correlated with improved O 2 uptake ability. Ladder-like silsesquioxanes (SSQs) and TiO 2 have been functionalized with methacryloyloxypropyl chains and embedded in a polybutadiene (PB) matrix giving rise to hybrid (organic–inorganic) nanocomposites (NCs) capable of acting as oxygen scavenging materials. The joint use of infrared spectroscopy, small-angle X-ray scattering, and permittivity measurements highlighted that the presence of TiO 2 , regardless of its modification, does not significantly alter the structure of the NCs, but just reduces the crosslinking degree and induces a local disorganization of the ladder-like SSQ stacks. The introduction of an optimum amount (0.5 wt%) of modified TiO 2 within the polymeric matrix enhanced the oxygen uptake rate of ca. 70% with respect to the sole polymeric material. Moreover, the uptake kinetics changes from the first to second order with respect to the PB amount, clearly indicating different oxidation mechanisms. NCs containing modified TiO 2 showed an oxygen uptake rate ranging from 30 to 60% higher than that achievable in the presence of bare TiO 2. The superior activity of the materials containing modified TiO 2 has been related to mechanistic aspects. Fluorescence and electron spin resonance spectroscopies allowed to underline the role of singlet oxygen within the polymeric matrix, although the known photochemical oxidation of PB and the TiO 2 induced hydroxyl radical mediated oxidation cannot be excluded. These results open the route to highly efficient flexible oxygen scavenging materials for the protection of electronic devices such as organic based light emitting diodes, solar cells, and liquid crystal displays, which require high targets of protection from oxygen and water. [ABSTRACT FROM AUTHOR]

Co3O4 thin films and nanosystems are implemented in a broad range of functional systems, including gas sensors, (photo)catalysts, and electrochemical devices for energy applications. In this regard, chemical vapor deposition (CVD) is a promising route for the fabrication of high-quality films in which the precursor choice plays a key role in the process development. In this work, a heteroleptic cobalt complex bearing fluorinated diketonate ligands along with a diamine moiety [Co(tfa)2·TMEDA; tfa = 1,1,1-trifluoro-2,4-pentanedionate and TMEDA = N,N,N′,N′-tetramethylethylenediamine] is investigated as a potential Co molecular precursor for the CVD of Co3O4 systems. For the first time, the compound is characterized by crystal structure determination and comprehensive analytical studies, focusing also on its thermal properties and fragmentation patterns, important figures of merit for a CVD precursor. The outcomes of this investigation, accompanied by detailed theoretical studies, highlight its very favorable properties for CVD applications. In fact, growth experiments under oxygen atmospheres containing water vapor revealed the suitability of Co(tfa)2·TMEDA for the fabrication of high-quality, phase-pure Co3O4 thin films. The versatility of the proposed strategy in tailoring Co3O4 structural/morphological features highlights its potential to obtain multi-functional films with controllable properties for a variety of eventual technological end-uses. [ABSTRACT FROM AUTHOR]

Organic phase change materials (PCMs) represent an effective solution to manage intermittent energy sources as the solar thermal energy. This work aims at encapsulating docosane in organosilica shells and at dispersing the produced capsules in epoxy/carbon laminates to manufacture multifunctional structural composites for thermal energy storage (TES). Microcapsules of different sizes were prepared by hydrolysis-condensation of methyltriethoxysilane (MTES) in an oil-in-water emulsion. X-ray diffraction (XRD) highlighted the difference in the crystalline structure of pristine and microencapsulated docosane, and 13C solid-state nuclear magnetic resonance (NMR) evidenced the influence of microcapsules size on the shifts of the representative docosane signals, as a consequence of confinement effects, i.e., reduced chain mobility and interaction with the inner shell walls. A phase change enthalpy up to 143 J/g was determined via differential scanning calorimetry (DSC) on microcapsules, and tests at low scanning speed emphasized the differences in the crystallization behavior and allowed the calculation of the phase change activation energy of docosane, which increased upon encapsulation. Then, the possibility of embedding the microcapsules in an epoxy resin and in an epoxy/carbon laminate to produce a structural TES composite was investigated. The presence of microcapsules agglomerates and the poor capsule-epoxy adhesion, both evidenced by scanning electron microscopy (SEM), led to a decrease in the mechanical properties, as confirmed by three-point bending tests. Dynamic mechanical analysis (DMA) highlighted that the storage modulus decreased by 15% after docosane melting and that the glass transition temperature of the epoxy resin was not influenced by the PCM. The heat storage/release properties of the obtained laminates were proved through DSC and thermal camera imaging tests. [ABSTRACT FROM AUTHOR]

Membranes of polyamine (PA-SiNH 2 ) m , containing silica reacted with 3-aminopropyltriethoxysilane (APTES) in hydrolytic conditions were prepared via solution casting, followed by methylation and ion exchange process. The influence of amino-functionalized silica (Si-NH 2 ) on the properties of the obtained membrane was investigated. Fourier transform infrared spectroscopy (FTIR) and Nuclear magnetic resonance spectroscopy (NMR) were used to investigate the chemical features of the silica and its interaction with the polyamine polymer. The results of thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) of the modified membrane confirmed it is stable up to 300 °C. The thermal stability is the result of the interaction of modified silica particles and polyamine polymer. It was demonstrated that the performance of the (PA-SiNH 2 ) m anion exchange membrane is greatly improved by incorporation of silica nanoparticles as compared with the anion exchange membrane (PK-PDAPm), which doesn't contain silica. Therefore, the (PA-SiNH 2 ) m is a suitable candidate for electrochemical applications. [ABSTRACT FROM AUTHOR]

The present study reports on the development and exploitation of an original filler system, based on alumina nanoparticles (NPs) and polyhedral silsesquioxane (POSS) units, namely Al 2 O 3 @POSS, where the remarkable compatibilization and thermomechanical features imparted by the silsesquioxane cage units "makes an alliance" with the enhanced thermal conductivity of Al 2 O 3 NPs. The target is to supply rubber nanocomposites with improved heat transport and mechanical properties potentially applicable in tires formulation. The hybrid filler was prepared by a double-step approach consisting of a first silanization of Al 2 O 3 with a methacrylate silane and subsequent grafting of OctaMethacrylPOSS through a radical reaction mediated by dicumyl peroxide as radical initiator. The material was characterized in depth in terms of structure, surface, and morphology and then used for producing, by solvent-casting technique, polybutadiene composites. The idea is to supply and test a model alumina-rubber based system which allows to better unveil the role played by the silsesquioxane units, thanks to the absence of other components (i.e. rubber polymers, vulcanization curatives and filler) usually included in real rubber formulations for tires. The comprehensive thermomechanical and morphological characterization of the nanocomposites highlighted the key role played by POSS units decorating the alumina surface, which assure both the compatibility between filler and polymer host, and an homogeneous distribution and continuous networking of the alumina NPs. This positively influences not only the heat transport, providing thermal conductive pathways that raise the thermal diffusivity even at low filler loadings (+60–70% with respect to composite enclosing bare alumina at a concentration of 15–10 v/v %) but also the storage modulus, paving the way toward a potential exploitation of Al 2 O 3 @POSS hybrid filler in large-scale formulations of rubber composites, namely those employed for tires. [Display omitted] [ABSTRACT FROM AUTHOR]

• Fly ash (FA) and flame retardants were evaluated to fire retard polylactide. • Partial substitution of FR systems by FA allowed to improve the fire performance. • Interactions between flame retardants and FA were observed and new components are identified by XRD and NMR. For a long time, fly ash has been considered as pure waste of coal power plants. Nevertheless, unique properties and compositions that vary with the material's origin make fly ash appealing as an engineering material in various applications. Thus, the opportunity to reduce the environmental footprint of polylactide through the incorporation of fly ash as a component of flame retardant systems has been investigated. Combinations of fly ash with ammonium polyphosphate and/or melamine polyphosphate were made for a global loading of 25 wt% with various rates of substitution of the flame retardants. Fire performance has been studied from cone calorimeter experiments as well as the use of pyrolysis combustion flow calorimeter (PCFC) and the UL94V test. The interpretation of the fire retardant mechanisms has been performed through the examination of cone calorimeter residues by scanning electronic microscopy, X-ray microanalysis, X-ray diffraction (XRD) and multinuclear solid-state NMR. It can be shown that fly ash is mainly composed of spherical particles which are thermally stable at cone calorimeter tests when used alone in PLA. Conversely, fly ash behaves as a reactive component with both flame retardants, leading to the formation of new crystalline and amorphous compounds as shown by XRD and NMR. Synergistic effects in fire performance resulting from the reactive behavior of fly ash can be highlighted and are ascribed to fire retardant mechanisms acting in the condensed phase, and corresponding to the conservation of high phosphorus contents in the condensed phase. [ABSTRACT FROM AUTHOR]

Organic–inorganic nanobuilding blocks (NBBs) based on silsesquioxanes (SSQs) have potential applications as nanofillers, thermal stabilizers, and rheological modifiers, which can improve thermomechanical properties of polymer hosts. The possibility to tune both siloxane structure and pendant groups can promote compatibilization and peculiar interactions with a plethora of polymers. However, the control on SSQs molecular architecture and functionalities is usually delicate and requires careful synthetic details. Moreover, investigating the influence of NBBs loading and structure on the hybrid interface and, in turn, on the polymer chains mobility and mechanical properties, may be challenging, especially for low-loaded materials. Herein, we describe the preparation and characterization of polybutadiene (PB) nanocomposites using as innovative fillers thiol-functionalized SSQs nanobuilding blocks (SH-NBBs), with both tailorable functionality and structure. Swelling experiments and, more clearly, solid-state NMR, enlightened a remarkable effect of SH-NBBs on the molecular structure and mobility of the polymeric chains, envisaging the occurrence of chemical interactions at the hybrid interface. Finally, thermal and DMTA analyses revealed that nanocomposites, even containing very low filler loadings (i.e. 1, 3 wt%), exhibited enhanced thermomechanical properties, which seem to be connected not only to the loading, but also to the peculiar cage or ladder-like architecture of SH-NBBs. [ABSTRACT FROM AUTHOR]

The production of stable suspensions of strontium-substituted hydroxyapatite (Sr-HA) nanopowders, as Sr ions vector for bone tissue regeneration, was carried out in the present work. Sr-HA nanopowders were synthesized via aqueous precipitation methods using Sr 2 + amount from 0 to 100 mol% and were characterized by several complementary techniques such as solid-state Nuclear Magnetic Resonance spectroscopy, X-ray diffraction, Infrared spectroscopy, N 2 physisorption and Transmission Electron Microscopy. The substitution of Ca 2 + with Sr 2 + in HA is always isomorphic with gradual evolution between the two limit compositions (containing 100% Ca and 100% Sr), this pointing out the homogeneity of the synthesized nanopowders and the complete solubility of strontium in HA lattice. Strontium addition is responsible for an increasing c/a ratio in the triclinic unit cell. A significant variation of the nanopowders shape and dimension is also observed, a preferential growth along the c-axis direction being evident at higher strontium loads. Modifications in the local chemical environment of phosphate and hydroxyl groups in the apatite lattice are also observed. Stable suspensions were produced by dispersing the synthesized nanopowders in bovine serum albumin. Characterization by Dynamic Light Scattering and ζ-potential determination allowed to show that Ca 2 + → Sr 2 + substitution influences the hydrodynamic diameter, which is always twice the particles size determined by TEM, the nanoparticles being always negatively charged as a result from the albumin rearrangement upon the interaction with nanoparticles surface. The biocompatibility of the suspensions was studied in terms of cell viability, apoptosis, proliferation and morphology, using osteosarcoma cell line SAOS-2. The data pointed out an increased cell proliferation for HA nanoparticles containing larger Sr 2 + load, the cells morphology remaining essentially unaffected. [ABSTRACT FROM AUTHOR]

The paper presents a new approach, covering wood with silica-based material in order to protect it from spoilage due to microbial colonisation and avoiding the loss of the natural features of the wood. Wood specimens derived from wine barrels were treated with methyltriethoxysilane in gas phase, leading to the deposition of a silica nanofilm on the surface. 29 Si and 13 C solid state Nuclear Magnetic Resonance and Scanning Electron Microscope–Energy Dispersive X-ray analysis observations showed the formation of a silica polymeric film on the wood samples, directly bonding with the wood constituents. Inductively Coupled Plasma-Mass Spectroscopy quantification of Si showed a direct correlation between the treatment time and silica deposition on the surface of the wood. The silica-coated wood counteracted colonisation by the main wine spoilage microorganisms, without altering the migration from wood to wine of 21 simple phenols measured using a HPLC-Electrochemical Coulometric Detection. [ABSTRACT FROM AUTHOR]

Iron(III) oxide nanomaterials are extremely promising for the development of magnetic devices, gas sensors, photocatalysts, and photoelectrodes for solar water splitting. The fabrication of such systems by chemical vapor deposition (CVD) relies on the use of molecular sources joining shelf-stability, high volatility, and clean decomposition. Herein, we report for the first time on a versatile iron(II) precursor, namely Fe(tfa) 2 TMEDA (tfa = 1,1,1-trifluoro-2,4-pentanedionate; TMEDA = N , N , N′ , N′ -tetramethylethylenediamine), combining the above features with a simple molecular concept. A theoretical-experimental characterization confirmed the compound spectroscopic purity and monomeric nature, and enabled to elucidate its structural, vibrational and electronic properties, along with its fragmentation pathway and thermal behavior. The ideal Fe(tfa) 2 TMEDA characteristics for CVD applications were finally validated through the fabrication of high purity iron oxide nanomaterials. The latter, comprising the sole metastable β-Fe 2 O 3 polymorph rather than the most stable rust (α-Fe 2 O 3), were characterized by the occurrence of oxygen defects and a nano-organization tunable as a function of growth temperature and reaction atmosphere. [Display omitted] • An iron(II) diketonate-diamine precursor is proposed for CVD of Fe 2 O 3 nanomaterials. • A theoretical/experimental approach is adopted for Fe(tfa) 2 TMEDA characterization. • A pure adduct with a fully saturated Fe(II) coordination sphere is obtained. • The complex has a high shelf stability, a good volatility and a clean fragmentation. • The compound validation in CVD afforded the scarcely investigated β-Fe 2 O 3 polymorph. [ABSTRACT FROM AUTHOR]

Abstract: Here we describe the step-wise grafting of the fluorophore dansyl chloride on the interlayer aluminol groups of kaolinite. The modified clay was characterized by powder RD, TGA, FT-IR and 27Al, 19Si, 13C MAS-NMR, which confirmed the achievement of the clay functionalization. The photophysical properties of the resulting nanohybrid material were evaluated by photoluminescence excitation and emission measurements. [Copyright &y& Elsevier]