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Silica as a stable and biocompatible material has attracted a great deal of interest, particularly concerning the synthesis of porous silica. Hierarchical Porous Silica (HPS) can be synthesized through nanoemulsion templating and sol–gel. The oil droplets of NE acted as a pore-forming agent and the sol-gel built the matrix around the oil droplets. The O/W-NE was prepared by the phase inversion composition (PIC) method. The effect of nanoemulsion volume (2.5, 25, and 50) and the effect of oil droplet diameter (65, 105, 150, 200, and 400 nm) on the HPS was studied. Samples were characterized by many characterization techniques. The microstructure of the samples is versatile with macropores distributed homogenously through the mesoporous silica matrix or hollow macroporous spheres. Both volume and hydrodynamic diameter of the nanoemulsions influence the microstructure through the oil/water interfacial area. The surface area ranges between 158 and 281 m2/g and the pore volume is between 0.63 and 6.59 cc/g. Highlights: Role of sodium silicate concentration/interfacial area is crucial. Hierarchical porous silica with a macroporous matrix or hollow spheres. Surface area ranges from 158 to 281 m2/g. The pore volume ranges between 0.63 and 6.59 cc/g. Surface roughness for pure silica is 2.48 and increases to 2.95 by nanoemulsion templating. [ABSTRACT FROM AUTHOR]

Hierarchical porous materials have attracted a considerable attention owing to the increased interest in their applications. Hierarchical Porous Silica (HPS) was synthesized by combining the sol‐gel of sodium silicate (SS) and oil in water nanoemulsion (O/W‐NE) templating. The oil droplets of NE acted as pore forming agent and the sol‐gel built the silica framework. The O/W‐NE was prepared by a low energy method, i. e. the phase inversion composition (PIC) method. The influence of pH of SS and NE on HPS was studied. The volume of ammonia, used to induce gelling, was studied as a factor influencing the HPS. The calcined samples were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), FTIR, N2 adsorption and small‐angel X‐ray scattering (SAXS). The results show that the microstructure is highly affected by pH and can be; macropores inserted in a dense matrix; a blend of a dense and a porous structure; or fully hierarchical porous silica. HPS has a specific surface area of 240 m2/g and a large pore volume (1.5 cm3/g) and a surface roughness of 2.95. [ABSTRACT FROM AUTHOR]

Mesoporous thin films were prepared by dip-coating with a purely aqueous method, as a substitute for the alcohol-based evaporation-induced self-assembly route. Unlike other aqueous routes that require a very slow pulling rate possible only using high performance dip-coaters, as a result of the high surface tension of water, this new process works with standard dip-coaters and at similar pulling rates as are used for the evaporation-induced self-assembly route. This unique asset is the result of the synthesis of prefabricated self-assembled silicate/organic hybrid micelles. These building blocks are concentrated before use, which provides a gelling edge after moderate evaporation. As a result, defect-free continuous mesoporous films with well-organized hexagonally packed pores were prepared after optimization of both the evaporation rate of the solution of hybrid micelles and the dip-coater pulling rate. Graphic Abstract: The transmission electron microscopy observation reveals the hexagonally packed structure of mesoporous silica film. This nanostructure has already been observed on films prepared with the evaporation-induced self-assembly process, but it is the first time it is obtained with a pure aqueous method, based on prefabricated hybrid micelles, not on controlled evaporation of mesophases. [ABSTRACT FROM AUTHOR]

We report how the control of a single parameter, the co-surfactant, determines the phase transitions of oil-in-water swollen liquid crystals (SLCs) prepared with cetyltrimethylammonium bromide (CTAB), from cubic to hexagonal, lamellar, and finally sponge-like structures. SLCs are complex mixtures (surfactant + co-surfactant + water + salt + oil) usually prepared to form hexagonal mesophases, with cell parameters tunable between 3 and 30 nm. These hexagonal mesophases were successfully used as nanoreactors to prepare a broad range of nanostructured materials. Because the potential of these mesophases as adaptive nanoreactors has not been extended to other liquid crystal geometries than the hexagonal, we studied in a first step the structure evolution of SLCs made with CTAB, cyclohexane, pentanol-1, water and different stabilising salts. We used small-angle X-ray scattering (SAXS), polarised light microscopy and Freeze-Fracture TEM to provide a partial phase diagram and list the different mesophases obtained as a function of composition. We report that the adjustment of a single parameter, the co-surfactant (pentanol-1), determines the phase transition between cubic, hexagonal, lamellar, and sponge-like structures, all other parameters such as the nature and concentration of salt, or amount of oil being constant. [ABSTRACT FROM AUTHOR]

We describe the generation and properties of TiO2-based macroscopic fibers designed for the photodecomposition of volatile organic compounds (VOC). We made use of a continuous industrially scalable extrusion process employing hybrid sols of amorphous titania nanoparticles, polyvinyl alcohol (PVA), and optionally latex nanoparticles. This process allowed for the continuous generation of hybrid TiO2/latex/PVA or TiO2/PVA macroscopic fibers. Upon thermal treatment in air, we obtained biphasic porous fibers containing the anatase phase of TiO2 with 10-15% of brookite. These fibers, which can be manufactured as several hundred meters of length reels, provide significantly improved phototocatalytic efficiency compared to our previous work. Their efficiency is now comparable to the commercial Quartzel®PCO photocatalyst for gas-phase acetone mineralization. [ABSTRACT FROM AUTHOR]

Hybrid materials that are composed of a polymeric material interfaced with an inorganic, metal oxide material have been a rapidly expanding research area in the last few decades. However, interfacial regions remain an important area of focus, and as such hybrid materials do not always possess a very robust or stable interface. Tailor-made interfacial molecules have been successfully reported but material scientists wishing to develop composite interfacial materials would favorably use commercial solutions. Our study shows how we can leverage a commercially available organophosphonic acid group that is coupled with a 2-bromo isobutyrate initiator for surface initiated atom transfer radical polymerization (SI-ATRP) for use as a strong interfacial molecule. We illustrate this mechanism with both nanoparticles of titania and flat titania substrates used as the grafting support and polymerization anchoring points. We demonstrate that the size of the organophosphonic acid initiator, specifically the carbon spacer between the reactive groups, controls the stability of the molecule. The actual covalent linkage between the phosphonic acid group and the titania surface while also leaving the ATRP initiating group able to start the polymerization, is confirmed via31P solid state NMR spectroscopy, liquid 1H NMR spectroscopy XPS, DLS and SEM. [ABSTRACT FROM AUTHOR]

The photocatalytic properties of titanium dioxide depend not only on its electronic properties, but also on the material size and shape, which can increase interactions between the reactants and catalyst. Most studies to date show that reducing the particle size down to the nanoscale increases photocatalytic efficiency, as a result of a higher surface to volume ratio and because a larger proportion of the material is actually irradiated by light. We demonstrate that a multiscale shape design, which integrates surface roughness, particle shape, and 1D material processing and orientation, can favor photocatalytic properties in the solid-gas regime, especially mineralization (conversion into CO2), when the hierarchical 1D orientation of the material is combined with unidirectional gas flow. Several materials with hierarchical structure were prepared and characterized. They have been tested for the photocatalytic mineralization of gaseous acetone and compared with commercial catalysts. Our study reveals that a suitable combination of multiscale design and optimization of the material orientation and gas flow favors high mineralization. [ABSTRACT FROM AUTHOR]