Structuring of Alkyl-Triazole Bridged Silsesquioxanes

Non-porous bridged silsesquioxanes (BSs) were produced by sol-gel reactions and self-directed assembly, in the presence of an acid catalyst and a large excess of water, from bridged organosilane precursors (BOPs) synthesized by click chemistry. The rational design of the compounds, comprising an amine group and alkyl chains with variable length (n), pendant and anchored on a single position to a triazole ring, and the control of acid content (w, moles of acid per moles of BOP) enabled the tuning of the morphology and structure of the BSs. At n=6, 12 and 16, and w=0.2 amorphous hybrids were produced as uniform isotropic micro- to nanospheres. Structuring resulted at n =16 and w=1.2 or n=20 and w=0.2, yielding lamellar bilayer structures. In the case of the BS with n=20 and w=1.2 a lamellar bilayer phase and a minor hexagonal 2D structure emerged. The quite unusual formation of the latter structure was attributed to the presence of a chloride ion close to the proton located between the N(2) atom of the triazole ring and the amine group of the organic spacer, acting as a curvature agent

Submicron coating of SiO2 nanoparticles from electrophoretic deposition

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Control of the nanocrystalline zirconia structure through a colloidal sol-gel process

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Amidophosphonate ligands as cerium extractants in supercritical CO2

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Thin polymeric CuO film from EPD designed for low temperature photothermal absorbers

International audienceThe creation of a tandem solar absorber based on highly UV–Vis–NIR absorbing nanofilm deposited onto a highly IR reflecting platinized silicon wafer is processed through electrophoretic deposition (EPD). The stabilization of a CuO colloidal aqueous suspension is first studied by adding polyethyleneimine (PEI) as cationic polymer acting both as charging agent and as electro-steric stabilizer. The colloidal stability as a function of the suspension pH is investigated prior to EPD, by Laser Doppler Velocimetry and atomic force microscopy. Tandem absorbers are obtained by varying different EPD parameters to control the thickness and the morphology of the film, in order to tune and optimize the final optical properties. The deposition thickness is then compared relative to the applied potential difference and the deposition time range. The morphology of the deposits and the thickness of the coatings are analysed by scanning electron microscopy (SEM). The density is obtained from energy-dispersive X-ray spectroscopy (EDX) using X-film software, total organic carbon (TOC) and Hamaker equation. CuO tandem absorbers are found to possess a high density with homogeneous and crack-free surfaces. Finally, absorptance (α) and emittance (ε) are calculated from the reflectance spectra of the UV–Vis–NIR and the Fourier Transform Infra-Red (FTIR) spectroscopy respectively. These latter values are combined to determine the efficiency (ƞ) of the tandem material

Radiation damage of mesoporous silica thin films monitored by X-ray reflectivity and scanning electron microscopy

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Structuring of di-alkyl-urethanesils

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Extra-framework zirconium clusters in metal organic framework DUT-67 controlled by the choice of the metal precursor

DUT-67 zirconium-thiophenedicarboxylate (TDC) MOFs have been synthesized in the presence of formic acid from different zirconium precursors. The materials formed have been characterized by X-ray diffraction, nitrogen sorption, scanning electron microscopy, and thermal gravimetry. Rietveld structure refinement has permitted to localize inside the microporosity zirconium and oxygen atoms of extraframework clusters (EFCs), whose conformation depended on the nature of the zirconium precursor. Dissolution-condensation processes of ZrCl4 and ZrOCl2 during the synthesis gave rise to Zr6 EFCs in one of every six cuboctahedral pores. Less numerous zirconia-like Zr12 oxo-clusters were formed from Zr isopropylate, whereas characteristic Zr8 nitro-clusters were formed from Zr oxonitrate. The distances between oxygen atoms of EFCs and framework were compatible with the presence of additional TDC linkers connected to the EFCs. The results have been interpreted in terms of competition between Zr species during the condensation of the MOF network