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Boric acid (BA) was reacted with 3-glycidyloxypropyltrimethoxysilane (GPTMOS) in diethylene glycol dimethyl ether, 1,4-dioxane or without using any solvent under reflux condition to obtain epoxyborosiloxane resins. A gelled product was obtained irrespective of solvent (1,4-dioxane/diethylene glycol dimethyl ether) used when BA and GPTMOS were reacted in 0.5:1 mole ratio followed by the removal of solvent and methanol (byproduct) by flash evaporation. Epoxyborosiloxane resins soluble in common organic solvents and having epoxy value of 3.8–4.2 eqv/kg were obtained when BA and GPTMOS were reacted in 0.5:1.5 mole ratio in 1,4-dioxane followed by flash drying or freeze drying. These resins leave behind ceramic residue of 39–44% at 800 °C in inert atmosphere as indicated by thermogravimetric analysis. Epoxyborosiloxane resin exhibiting M ¯ w of 4070 and M ¯ n of 1600 and epoxy value of 4.4 eqv/kg was obtained by solventless process. In an attempt to improve the inorganic residue, epoxyborosiloxane resins containing vinylsiloxy units were synthesized from BA and a mixture of GPTMOS and vinyltriethoxysilane in 1,4-dioxane, diethylene glycol dimethyl ether (diglyme) or in bulk under reflux condition. The oligomer synthesized in dioxane is soluble in organic solvents and has M ¯ w of 4370 and M ¯ n of 2020 and epoxy value of 1.7 eqv/kg. The oligomer obtained by the solventless process exhibits M ¯ w and M ¯ n of 3460 and 1110 and epoxy value of 2.0 eqv/kg. These resins exhibit higher ceramic residue compared to epoxyborosiloxane resins. Soluble epoxyborosiloxane and epoxy(vinyl)borosiloxane oliogomers were characterized by 1 H-, 13 C- and 29 Si-NMR spectra. The oligomers contain T 2 (Si surrounded by two O–Si or O–B bonds) and T 3 (Si surrounded by three O–Si or O–B bonds) structural units as indicated by 29 Si-NMR spectra. Highlights Epoxyborosiloxane and epoxy(vinyl)borosiloxane resins were synthesized by reacting boric acid with 3-glycidyloxypropyltrimethoxysilane and with mixtures of 3-glycidyloxypropyltrimethoxysilane and vinyltriethoxysilane. Epoxyborosiloxane and epoxy(vinyl)borosiloxane resins synthesized by a solventless non-aqueous sol–gel process have epoxy value of 4.4 eqv/kg and 2 eqv/kg respectively. 29 Si-NMR spectral studies suggest that the resins contain T 2 (Si surrounded by two O–Si or O–B bonds) and T 3 (Si surrounded by three O–Si or O–B bonds) structural units. Incorporation of vinylsiloxy units enhances the thermal stability and ceramic residue of epoxyborosiloxane.

In this study, pure and Co-doped tin oxide (SnO 2 ) nanoparticles were synthesized by sol–gel method, and the effect of Co-doping on the structural, optical, photocatalytic, and antimicrobial activities was studied. The prepared samples were characterized by X-ray diffraction (XRD), high-resolution transmission electron microscopy, energy-dispersive X-ray spectroscopy, UV–visible diffuse reflectance spectroscopy, and N 2 adsorption/desorption analysis. The XRD patterns of all the samples are identified as tetragonal rutile-type SnO 2 phase which is further confirmed by TEM analysis. The optical spectra showed redshift in the absorption edge of doped samples, which enhances their absorption toward the visible light region. The photocatalytic activity of all the samples was assessed by monitoring the degradation of methylene blue solution under daylight illumination, and it was found that the photocatalytic activity significantly increases with the increase in dopant concentration, which is due to the effective charge separation of photogenerated electron–hole pairs. The antimicrobial studies investigated against standard bacterial and fungal strains showed enhanced antimicrobial activity in doped samples, which can be attributed to the production of reactive oxygen species and large surface area of the nanoparticles. Graphical abstract

The development of biomaterials with intrinsic antioxidant properties could represent a valuable strategy for preventing the onset of peri-implant diseases. In this context, quercetin, a naturally occurring flavonoid, has been entrapped at different weight percentages in a silica-based inorganic material by a sol-gel route. The establishment of hydrogen bond interactions between the flavonol and the solid matrix was ascertained by Fourier transform infrared spectroscopy. This technique also evidenced changes in the stretching frequencies of the quercetin dienonic moiety, suggesting that the formation of a secondary product occurs. Scanning electron microscopy was applied to detect the morphology of the synthesized materials. Their bioactivity was shown by the formation of a hydroxyapatite layer on sample surface soaked in a fluid that simulates the composition of human blood plasma. When the potential release of flavonol was determined by liquid chromatography coupled with ultraviolet and electrospray ionization tandem mass spectrometry techniques, the eluates displayed a retention time that was 0.5 min less than quercetin. Collision-activated dissociation mass spectrometry and untraviolet-visible spectroscopy were in accordance with the release of a quercetin derivative. The antiradical properties of the investigated systems were evaluated by DPPH and ABTS methods, whereas the 2,7-dichlorofluorescein diacetate assay highlighted their ability to inhibit the H 2 O 2 -induced intracellular production of reactive oxygen species in NIH-3T3 mouse fibroblast cells. Data obtained, along with data gathered from the MTT cytotoxicity test, revealed that the materials that entrapped the highest amount of quercetin showed notable antioxidant effectiveness.

In this study, silica thin film pH=6 (precursor TEOS:tetraethyl ortosilicate) developed from sol gel process and deposited (2 layers) directly onto alumina substrate(tubular support with 100 nm pore size) without depositing interlayer (interlayer-free).Then, the desalination process via pervaporation was applied to test the membranesperformanceusing artificial saline water and wetland saline water. Results show the decrease of water flux (1.9 to 1.43 kg m-2 h-1) and salt rejection(97 to 95%) when using artificial salty water (0-7.5 wt%) and the long-term stability of silica membrane was stable at 1.7 kg m-2 h-1 for over 100 hours when using wetland saline water as a feed.

Hybrid nanomaterials based on zinc oxide were synthesized via the sol–gel method, using different silane coupling agents: (3-glycidyloxypropyl)trimethoxysilane (GPTMS), phenyltriethoxysilane (PhTES), octyltriethoxysilane (OTES), and octadecyltriethoxysilane (ODTES). Morphological properties and the silane precursor type effect on the particle size were investigated using dynamic light scattering (DLS), environmental scanning electron microscopy (ESEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and X-ray diffraction (XRD). The bonding characteristics of modified ZnO materials were investigated using Fourier transform infrared spectroscopy (FTIR). The final solutions were deposited on metallic substrate (aluminum) in order to realize coatings with various wettability and roughness. The morphological studies, obtained by ESEM and TEM analysis, showed that the sizes of the ZnO nanoparticles are changed as function of silane precursor used in synthesis. The thermal stability of modified ZnO materials showed that the degradation of the alkyl groups takes place in the 300–500 °C range. Water wettability study revealed a contact angle of 142 ± 5° for the surface covered with ZnO material modified with ODTES and showed that the water contact angle increases as the alkyl chain from the silica precursor increases. These modified ZnO materials, therefore, can be easily incorporated in coatings for various applications such as anti-corrosion and anti-icing.

Sol–gel entrapment method was used to entrap bromothymol blue (BTB) pH indicator into mesoporous silica materials in the presence of cationic surfactants: 2-(hexadecyloxy)-2-oxoethyl-N,N,N-triethyl ammonium iodide (16E1Q) and 2-(hexadecyloxy)-2-oxoethanaminium-p-toluene sulfonate (16E1QS). The use of this new family of surfactants has modified the morphology and porosity of silica host matrix for better sensing capability and for faster response toward pH change. The physical interactions between BTB molecules and host mesoporous silica network were based on the nature of the surfactant. The presence of surfactants has shifted pKa values of more basic in comparison with that of BTB-entrapped silica system. Graphical Abstract

A facile method was developed for the fabrication of the methyltriethoxysilane based transparent and superhydrophobic coating on glass substrates. The transparent and hydrophobic coatings were deposited on the glass substrates, using spray deposition method followed by surface modification process. A spray deposition method generates hierarchical morphology and post surface modification with monofunctional trimethylchlorosilane decreases the surface free energy of coating. These combined effects of synthesis produces bio-inspired superhydrophobic surface. The deposited coating surface shows high optical transparency, micro-nano scale hierarchical structures, improved hydrophobic thermal stability, static water contact angle of about 167° ± 1°, low sliding angle about 2° ± 1° and stable superhydrophobic nature. This paper provides the very simple sol–gel approach to the fabrication of optically transparent, thermally stable superhydrophobic coating on glass substrates. This fabrication strategy may easily extend to the industrial scale up and high-technology fields.

In this paper, a simple method is presented for making a conductive and hydrophobic cotton fabric using a multi-walled carbon nanotube (MWCNT). The method is known as ‘the sol–gel method’. The conditions for the sol–gel process such as the solution pH, silane agent concentration, polymerization time, amount of MWCNT, and its fixation procedure were optimized. The hydrophobic properties of the modified fabric were characterized in terms of water contact angle (WCA) and water droplets penetration time. The surface morphology of the treated samples was evaluated using a scanning electron microscope. The surface resistivity of the prepared fabric was measured according to the 76-1995 AATCC test method. The abrasion and washing fastness of the fabric were also studied. In optimum conditions, the prepared cotton fabric proved to have such features as WCA = 146° and surface resistance = 40 kΩ cm −2 .

Sol–gel process is a very unique wet chemical method for producing advanced materials in various areas of research. An increasingly evolution trend of this process is to combine with other technologies, such as surface modification, hybridization, templating induction, self-assembly, and phase separation, for preparing new materials possessing controllable shape, unique microstructure, superior properties, and special application. The review aims to present the synthesis of several typical sol–gel-derived materials (monodisperse nanoparticles, hybrid coatings, hollow microspheres, aerogels, and porous monoliths) via sol–gel process combining with other technologies . Some examples of application of the sol–gel-derived materials are also included.

Superhydrophobic aerogel ORMOSIL (organically modified silicate) thin films with controlled refractive index were prepared by a one-pot sol–gel process without supercritical drying. The method involved the preparation of ORMOSIL particles by co-condensation of tetramethylorthosilicate (TEOS) and dimethyldiethoxysilane (DDS) and a further surface modification of ORMOSIL particles with hexamethylsilazane. The particle growth process of ORMOSIL sols and the drying process of aerogel ORMOSIL thin film are discussed in detail. The co-condensation of TEOS and DDS and the surface modification significantly improved the hydrophobicity and hence the environmental resistance of the thin films; the water contact angles of the thin films increased from 23° to 151°. A superhydrophobic aerogel ORMOSIL thin film with refractive index as low as 1.10 was obtained. In addition, the refractive indices can be tailored in the range of 1.10–1.23. Graphical Abstract Superhydrophobic aerogel ORMOSIL (organically modified silicate) thin films with controlled refractive index were prepared by sol–gel process without supercritical drying.