Anhydrous Sol Gel Research Articles

Anhydrous sol-gel synthesis of TiO2 nanoparticles: Evaluating their impact on protein interactions in biological systems

This study focused on the synthesis of anhydrous sol-gel synthesis of TiO2 nanoparticles using a hydrothermal route. The chemical properties of the synthesized TiO2 nanoparticles were confirmed through Fourier Transform Infrared Spectroscopy (FT-IR) and UV–Vis spectroscopy, highlighting their optical features. Additionally, Energy Dispersive X-ray Spectrometer (EDX) analysis revealed the high purity of the nanomaterial, while the Transmission Electron Microscope (TEM) displayed spherical particles ranging in size from ≥ 80 nm. Furthermore, X-ray diffraction analysis (XRD), Raman and HRTEM analyses indicated that the nanomaterial exhibits an anatase and rutile structure. When, Hen Egg-White Lysozyme (HEWL) incubated with TiO2 led to notable changes: reduced fluorescence indicating protein unfolding, increased light scattering showing protein aggregation, the presence of amyloid fibrils and hydrophobic regions, and reduced enzyme activity. FTIR spectroscopy revealed amyloid structure formation, while Dynamic Light Scattering confirmed the presence of larger protein oligomers. These findings highlight TiO2's adverse impact on HEWL structure and function, emphasizing the need for further research on nanoparticle toxicity in biological systems, particularly in biomedical applications.

Preparation and properties of Eu3+ or Ru(bpy)32+-doped TiO2-SiOR hybrids for luminescent solar concentrator

Eu3+ or Ru(bpy)32+-doped TiO2-SiOR (R-organic groups) hybrid films on Si wafers or silica glass slides were prepared by the anhydrous sol-gel process, from 3-aminopropyltriethoxysilane, dihydroxydiphenylsilanel and Ti(OBun)4 for luminescent solar concentrator, since Eu3+ and Ru(bpy)32+ ions could down-shift light frequency. Ti-O-Si bonds exist in the TiO2-SiOR films. Optical transmittances were ~90% in ~372 – 2500 nm for the undoped/Eu3+-doped films; but for the Ru(bpy)32+-doped film, there’s an absorption peak at ~470 nm with wide shoulder. For Eu3+-doped films, different photoluminescent spectra were obtained by excited with different wavelengths; but for Ru(bpy)32+ doped films, the same luminescent peaks at ~588 nm occurred under different excitation wavelengths. The decomposition temperature of hybrid was Td ~407 °C.

17% Non-Fullerene Organic Solar Cells with Annealing-Free Aqueous MoO x.

A charge transport layer based on transition metal‐oxides prepared by an anhydrous sol–gel method normally requires high‐temperature annealing to achieve the desired quality. Although annealing is not a difficult process in the laboratory, it is definitely not a simple process in mass production, such as roll‐to‐roll, because of the inevitable long cooling step that follows. Therefore, the development of an annealing‐free solution‐processable metal‐oxide is essential for the large‐scale commercialization. In this work, a room‐temperature processable annealing‐free “aqueous” MoOx solution is developed and applied in non‐fullerene PBDB‐T‐2F:Y6 solar cells. By adjusting the concentration of water in the sol–gel route, an annealing‐free MoOx with excellent electrical properties is successfully developed. The PBDB‐T‐2F:Y6 solar cell with the general MoOx prepared by the anhydrous sol–gel method shows a low efficiency of 7.7% without annealing. If this anhydrous MoOx is annealed at 200 °C, the efficiency is recovered to 17.1%, which is a normal value typically observed in conventional structure PBDB‐T‐2F:Y6 solar cells. However, without any annealing process, the solar cell with aqueous MoOx exhibits comparable performance of 17.0%. In addition, the solar cell with annealing‐free aqueous MoOx exhibits better performance and stability without high‐temperature annealing compared to the solar cells with PEDOT:PSS.

Flame resistance, physical and mechanical properties of UV-cured hybrid coatings containing low-hydroxyl-content sols via an anhydrous sol-gel process

Abstract As one of a series of our studies, starting with silica sol (TM2) and Si-P binary sol (SP5), two series of low-hydroxyl-content sols (LHCSs) were synthesized using an anhydrous sol-gel method. The stable storage time of LHCS-containing hybrid coatings was improved relative to that of hybrid coatings containing TM2 and SP5. The flame resistance and thermal stability of UV-cured hybrid coatings consisting of LHCS, epoxy acrylate of bisphenol A (SM6104) and tripropylene glycol diacrylate (TPGDA) were investigated by means of thermogravimetric analysis (TGA), limit oxygen index (LOI), cone calorimetry and a flammability test. The results indicated that the flame resistance of LHCS-containing hybrid coatings was further improved over that of hybrid coatings containing TM2 and SP5. The improvements mainly included a longer ignition time and lower combustion heat. Hybrid coatings applied on the surface of wooden floors could offer long-lasting and significant protection against fire, showing outstanding practical value. In addition, the physical and mechanical properties of LHCS-containing hybrid coatings were negatively affected by the decrease of hydroxyl group contents and the Ti-containing component. A UV-curable phosphorus-containing resin (RAYLOK 1722) was introduced into the hybrid coatings containing LHCS. However, hybrid coatings containing RAYLOK 1722 showed only a small improvement in flame resistance, and their physical and mechanical properties were damaged by RAYLOK 1722.

Synthesis and performance of antifouling and self-cleaning polyethersulfone/graphene oxide composite membrane functionalized with photoactive semiconductor catalyst.

This study was performed to synthesize membranes of polyethersulfone (PES) blended with graphene oxide (GO) and PES blended with GO functionalized with photoactive semiconductor catalyst (TiO2 and ZnO). The antifouling and self-cleaning properties of composite membranes were also investigated. The GO was prepared from natural graphite powder by oxidation method at low temperature. TiO2 and ZnO nanopowders were synthesized by anhydrous sol-gel method. The surface of TiO2 and ZnO nanopowders was modified by a surfactant (myristic acid) to obtain a homogeneously dispersed mixture in a solvent, and then GO was functionalized by loading with these metal oxide nanopowders. The PES membranes blended with GO and functionalized GO into the casting solution were prepared via phase inversion method and tested for their antifouling as well as self-cleaning properties. The composite membranes were synthesized as 14%wt. of PES polymer with three different concentrations (0.5, 1.0, and 2.0%wt.) of GO, GO-TiO2, and GO-ZnO. The functionalization of membranes improved hydrophilicity property of membranes as compared to neat PES membrane. However, the lowest flux was obtained by functionalized membranes with GO-TiO2. The results showed that functionalized membranes demonstrated better self-cleaning property than neat PES membrane. Moreover, the flux recovery rate of functionalized membranes over five cycles was higher than that of neat membrane.

Fluorine-containing photocurable hybrid coatings via anhydrous sol-gel method

In this study, fluorine-doped photocurable hybrid coatings were prepared by combining UV-curing technology with an anhydrous sol–gel method. First, methacryloxymethyl triethoxysilane (MEMO) was hydrolyzed via an anhydrous sol–gel process. Then MEMO was mixed with acrylic oligomers and predetermined amounts of fluoroacrylate resin. UV curable hybrid coatings were applied on corona-treated plexiglass substrates. The addition of fluorine showed a significant impact on the properties of the coatings. As the fluorine content was increased in the formulations, flame retardancy and the contact angle values of the coatings increased. It was found that the optical transmittance of the coatings was higher than 95%. The surface morphology of the hybrid films was characterized by scanning electron microscopy (SEM). The chemical composition of the surface of the coatings was identified by energy dispersion spectrum (SEM–EDS) technique. SEM studies indicated that inorganic particles were dispersed homogenously throughout the organic matrix. J. VINYL ADDIT. TECHNOL., 2014. © 2014 Society of Plastics Engineers

Erratum to “Preparation of New Titanium Oxy Nitride based electro catalysts Using An Anhydrous Sol-gel Method for Water Electrolysis in Acid Medium” [Int. J. Hydrogen Energy 37 (9) (May 2012) 7405–7417

Erratum to “Preparation of New Titanium Oxy Nitride based electro catalysts Using An Anhydrous Sol-gel Method for Water Electrolysis in Acid Medium” [Int. J. Hydrogen Energy 37 (9) (May 2012) 7405–7417

Preparation of new titanium oxy nitride based electro catalysts using an anhydrous sol-gel method for water electrolysis in acid medium

Titanium oxy nitride has been fabricated for the first time from anhydrous Sol-gel Method and used as anode for water electrolysis in acid medium. It is shown that the properties of this material are highly dependent on the calcination temperature. The conductivity increases from insulator (titanium dioxide type) to metallic (titanium nitride type) when the calcination temperature rose from 500 °C to 1000 °C. When the catalyst material is calcinated at 700 °C, the rutile structure of titanium dioxide is obtained and agrees well with those obtained with the TGA-DSC results. These results also show that the structure of the osbornite of titanium nitride appears at 1000 °C. The BET surface area also increases with the calcination temperature. The morphology of the calcinated samples gradually breaks into smaller conchoidal fracture particles when the sample preparation temperature increases. Electrochemical voltage–current polarization curves of the oxygen evolution reaction in sulphuric acid on these anodes electrodes confirm that the materials calcinated at 800 °C or even at higher temperatures exhibit a low Tafel slope and a high electrochemistry surface area which are both known as good values for the oxygen evolution in acid medium. The results of this study suggest that our titanium oxy nitride prepared by an anhydrous sol-gel method followed by calcination is an interesting anode catalyst for water electrolysis. Its performance for this reaction is compared to those of some noble metal oxides.

Photocurable cyanate ester containing hybrid coatings by an anhydrous sol–gel technique

This work reports the synthesis and characterization of hybrid coatings obtained by UV curable anhydrous sol–gel process. Chemical structure of the products was confirmed using spectroscopic methods such as infrared and nuclear magnetic resonance spectroscopy. The properties of the hybrid coatings such as thermal and mechanical properties were investigated in detail by scanning electron microscope, thermogravimetric analysis, and mechanical measurement. Cure kinetics of the coating formulations was investigated by differential scanning photo-calorimetry (Photo-DSC). Cross cut adhesion, pendulum hardness, gloss, pencil hardness, MEK rub test were also performed to measure the coating performance of the hybrid coatings. The results indicate that the addition of the appropriate amount of CPM and sol–gel can effectively improve the thermal and mechanical properties.

Thermal and neutron shielding properties of 10B containing UV cured hybrid coatings

10B containing organic–inorganic hybrid coating material based on a UV-curable formulation was prepared via anhydrous sol–gel technique. UV curable coatings were applied on Plexiglas (PMMA) substrates. The molecular structure of the coating material was analyzed by ATR-FTIR spectroscopy technique. The characterization of the UV-curable coating was evaluated by various techniques such as gel content, abrasion resistance, chemical resistance, pencil hardness, pendulum hardness, MEK rubbing test, contact angle, cross-cut test, gloss, transmittance test, neutron absorption, Limiting Oxygen Index and stress–strain tests. Hybrid coatings showed a significant enhancement in radiation shielding properties. The thermal behavior of coatings was also evaluated. It is observed that the thermal stability of coatings mainly depends on their boron and silicate contents. Results of all analysis conducted on hybrid films, and coatings were discussed.

Preparation of photocurable silica–titania hybrid coatings by an anhydrous sol–gel process

Photocurable silica-titania hybrid coatings were prepared through an anhydrous sol–gel process. Moreover, test samples were prepared by the addition of definite ratios of fluoro acrylate oligomers into the formulations to manage the optical properties of transmitted light. Formulations were applied to corona-treated polycarbonate substrates. Upon adding the inorganic component to the coating material, thermal, mechanical, and other properties, such as hardness, gloss, contact angle, and flame resistance were improved. The photocured hybrid films showed an increase in the refractive index with increasing the titanium tetraisopropoxide content. As expected, a decrease was observed in the refractive index of the coatings with the incorporation of fluoro acrylate resin. The surface morphology of the hybrid films was characterized by ESEM analysis. In addition the chemical composition of the surface of the coatings was identified by ESEM–EDS technique. ESEM studies indicated that inorganic particles were dispersed homogenously throughout the organic matrix.

Preparation and characterization of UV‐curable, boron‐containing, transparent hybrid coatings

AbstractA series of ultraviolet (UV)‐curable, boron‐containing hybrid coatings were prepared by an anhydrous sol–gel technique from a mixture of an acrylated bisphenol A based epoxy resin, methacryloxymethyl triethoxysilane, and boric acid. The use of boric acid allowed the hydrolysis and condensation of hybrid silicon alkoxides without the further addition of water or a catalyst. The chemical structure of the boron‐containing hybrid coatings was characterized with Fourier transform infrared, real‐time infrared, and 29Si cross‐polarization/magic‐angle spinning NMR techniques. UV‐curable coatings were applied to polycarbonate and Plexiglas substrates. The physical and mechanical properties of the UV‐cured coatings (e.g., pendulum hardness, pencil hardness, contact angle, gel content, methyl ethyl ketone rubbing test, tensile test, abrasion resistance, chemical resistance, neutron absorption, and limiting oxygen index) were examined. The hybrid coatings showed a significant enhancement in their radiation‐shielding properties. The thermal behavior of the coatings was also evaluated. It was observed that the thermal stability of the coatings mainly depended on their boron and silicate contents. The results of all analyses of the free films and coatings were examined. © 2010 Wiley Periodicals, © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011

Effects of TiO2 and ZrO2 on optical properties of organic–inorganic hybrid polymers and thin films

TiO2- and ZrO2-doped hybrid polymers were prepared by an anhydrous sol–gel process, and their optical properties were studied. Incorporation of TiO2 and ZrO2 was found useful in promoting sol–gel condensation reactions and reducing the OH absorption and optical losses of the hybrid polymers. The thermo-optic properties of the TiO2- and ZrO2-doped hybrid polymer thin films were measured, and linear functions were observed for the changes in film thickness and refractive index during thermal scanning tests. The photosensitivity of the hybrid materials upon UV irradiation was observed to increase with the increase of the content of TiO2 and ZrO2, and the mechanisms for TiO2 and ZrO2 enhancing the photosensitivity of the hybrid polymers are discussed.

Influence of TiO2 on Second Harmonic Generation in Disperse Red -1 doped Organic-Inorganic Hybrid Thin Films

AbstractDisperse Red 1 (DR1) doped TiO2-SiO2 inorganic-organic hybrid polymers were prepared by an anhydrous sol-gel process and second harmonic generation (SHG) of the fundamental 1053nm in these polymeric thin films was measured using Maker-fringe method. The nonlinear optical activity of DR1 in the thin films was studied by corona poling at different temperature (from room temperature to 140°C), and the stability of SHG after switching off corona power was evaluated by analyzing the SHG decay dynamics. Experimental results showed that the stability of the SHG of DR1 significantly increases with the cross-linkage degree of the TiO2SiO2 hybrid polymer network, and that the second harmonic coefficient d33 increases as the DR1 concentration increases. TiO2-doping can promote the polymerization of unsaturated C=C double bonds in the hybrid thin films during in-situ hot poling, enhancing the cross-linkage of the network of the hybrid material, and resulting in a great improvement of the stability of SHG. The excellent stability of second harmonic generation in the hybrid polymer thin films suggests that TiO2-doped inorganic-organic hybrid polymer is promising for chromophore doping for nonlinear optical applications.

Real sol-gel synthesis of catalytically active aluminium fluoride

Amorphous AlF3 prepared via an anhydrous sol-gel synthesis route exhibits high surface area and Lewis acidity far beyond those known for crystalline AlF3 phases. Its catalytic properties are comparable to those of SbF5. Basis of its unusual properties is a sol-gel fluorination with anhydrous HF in organic solvents yielding first a wet Al-F-sol-gel, which can be dried and eventually post-fluorinated. All parts of the synthesis route were thoroughly investigated. The results of these investigations together with detailed analysis of the Al-F-materials obtained are reported and discussed.

Photosensitivity of titania-doped hybrid polymer prepared by an anhydrous sol–gel process

Abstract Methacrylate-modified hybrid polymer with varied TiO2 concentrations was prepared by an anhydrous sol–gel process, and the effects of TiO2 on the photosensitivity of the hybrid polymer in the forms of wet films (before the polymerisation of the unsaturated C C bonds of methacrylate groups) and hard films (after the polymerisation of the unsaturated C C bonds with a pre-UV cross-linking and thermo-curing process) were studied. TiO2 doping was found useful for enhancing the photosensitive response to UV light irradiation in both wet and hard films. In wet films, TiO2 has a similar effect as a photo-initiator on accelerating the polymerisation of the unsaturated C C bonds of methacrylate groups, therefore TiO2 doping favours UV-patterning with photolithographic process for planar optical waveguides fabrication. In the fully polymerised TiO2-doped hard films, photosensitivity with a refractive index increase as large as 0.01 was firstly observed. The structural changes of the hybrid polymer upon UV irradiation were investigated by FT-IR and energy dispersive X-ray spectroscopic (EDXS) techniques, and the mechanisms for the photosensitivity in hard films were proposed.

Anhydrous Sol-Gel Synthesis of Titania-Doped Siloxane Polymer for Integrated Optics

Sol-gel synthesis of organic-inorganic hybrid materials for planar waveguides and devices has received growing interest due to its low-cost processing and good suitability for doping. Titania is an important optical dopant, but homogeneous incorporation of titania in silica is difficult to be achieved by the conventional sol-gel process (aqueous system) because of the significant difference between the hydrolysis rates of the precursors. In this paper, we report an anhydrous sol-gel process for synthesising titania-doped siloxane polymers. The process consists of a hydrolysis of 3-methacryloxypropyltrimethoxysilane (MPS) with boric acid under anhydrous conditions, and a condensation with dimethyldimethoxysilane (DMDMS), diphenyldimethoxysilane (DPhDMS) and titanium ethoxide (TET). Optical characterisations for the produced titania-doped polymer were performed, and results showed that TET doping is useful for reducing the OH concentration of the synthesised polymer and is also effective for improving the optical quality of spin coatings. DMDMS and DPhDMS are favourable in reducing the birefringence and in increasing the thermostability of the material, and the methacryl groups of MPS are UV-polymerizable, which is useful for low cost fabrication of waveguides by photolithographic process. The results of ellipsometry scanning measurements show that titania is homogeneously incorporated in the hybrid matrix, suggesting that the anhydrous sol-gel process is useful for preparation of UV-sensitive titania-doped siloxane polymers for optical applications.

Preparation and optical properties of titania-doped hybrid polymer via anhydrous sol–gel process

Incorporation of metal alkoxides (Ti, Zr, etc.) for tuning the optical properties of silica glasses by the sol–gel process is of significant interest for optical applications. In this paper, we report an anhydrous sol–gel process for preparation of photosensitive titania-doped hybrid glassy polymer with good homogeneity and high doping concentration (TiO2 up to 40mol%). The process consists of two steps: in the first step methacryloxypropyltrimethoxysilane (MPS) is hydrolyzed by boric acid through ligand exchange reaction (OH↔OR) under anhydrous conditions; and in the second step dimethyldimethoxysilane (DMDMS), diphenyldimethoxysilane (DPhDMS) and titanium ethoxide (TET) were added to condense with the silanols formed in the first step. The optical properties of the synthesized hybrid polymer were studied, and results showed that the hybrid material has low OH absorption, low optical losses (0.45dB/cm at 1550nm and 0.16dB/cm at 1310nm respectively), and good thermo-optical linearity with tuneable refractive index. The effect of TiO2 doping in reducing the OH concentration of the hybrid material was observed, and the mechanism for this effect is discussed.

Single-Step Microstructure Patterning in Titania-Doped Sol-Gel Glassy Thin Films with Electron Beams

ABSTRACTTo achieve a simplified microstructure patterning process, patterning in thin films with a singlestep exposure to UV-light or E-beam process for fabrication of integrated optical waveguides and components is of great interest in optics, because the complicated structure developing stage by wet chemical or plasma etching is not required. In this paper, we describe our study on the microstructure patterning in TiO2-doped hybrid glassy polymer thin films by irradiating with focused E-beam. An anhydrous sol-gel process based on hydrolysis and condensation of metal alkoxides with boric acid under non-hydrous conditions was applied to homogeneously incorporating TiO2into silica network, and transparent glassy TiO2-doped thin films with varied TiO2concentrations (up to 40 mol%) were prepared by spin coating the hybrid polymer onto fused silica substrates and silicon wafers. The TiO2-doped hybrid material showed a low OH absorption, low optical losses at the telecommunication windows (<0.40 dB/cm at 1550 nm and <0.20 dB/cm at 1310 nm respectively), good thermo-optical linearity and good thermal stability up to 200 °C. Single-step direct surface patterning in the TiO2-doped hybrid glassy films with focused electron beams irradiation showed that fine structure with resolution at submicron level can be fabricated. As the process does not need a developing (etching) process, the profiles of the lines fabricated by the E-beam direct writing showed few distortion. The high precise patterning microstructure with submicron feature sizes in the TiO2-doped hybrid glassy thin films may provide potentials for applications to the fabrication of optical gratings.

Synthesis of Photosensitive Organic-Inorganic Hybrid Polymers via Anhydrous Sol-Gel Process for Integrated Optics

AbstractPhotosensitive organic-inorganic hybrid polymers were synthesised for integrated optical and optoelectronic devices by a non-hydrous sol-gel process of hydrolysis/condensation of 3-methacryloxypropyltrimethoxysilane (MPS), diphenyldimethoxysilane (DPhDMS), and zirconium isopropoxide (TPZ) with boric acid under anhydrous conditions. The methacryl groups of MPS are UVpolymerizable, which are suitable for low cost fabrication of waveguides with a “UV write/develop” process. The incorporation of DPhDMS and TPZ was found useful in reducing the optical loss and in enhancing the thermostability of the polymer. The refractive index of the hybrid polymer is tuneable from 1.4950 to 1.5360 by variation of the ratio among MPS, DPhDMS and TPZ. Optical characterisation showed that the material has low optical losses at the telecommunications windows (0.16 dB/cm at 1310 nm and 0.4 dB/cm at 1550nm). The hybrid polymer also showed a low birefringence (1.2×10-4), a large thermo-optic (TO) coefficient (-2.77 ×10-4), and an outstanding linearity of dn/dT in a wide range of temperature (from 25 °C to 200 °C). Waveguides forming ability for the hybrid polymer with UV imprinting was also demonstrated.