Sol-gel Polymerization Process Research Articles

Advances in Aerogels Formulations for Pulmonary Targeted Delivery of Therapeutic Agents: Safety, Efficacy and Regulatory Aspects.

Aerogels are the 3D network of organic, inorganic, composite, layered, or hybrid-type materials that are used to increase the solubility of Class 1 (low solubility and high permeability) and Class 4 (poor solubility and low permeability) molecules. This approach improves systemic drug absorption due to the alveoli's broad surface area, thin epithelial layer, and high vascularization. Local therapies are more effective and have fewer side effects than systemic distribution because inhalation treatment targets the specific location and raises drug concentration in the lungs. The present manuscript aims to explore various aspects of aerogel formulations for pulmonary targeted delivery of active pharmaceutical agents. The manuscript also discusses the safety, efficacy, and regulatory aspects of aerogel formulations. According to projections, the global respiratory drug market is growing 4-6% annually, with short-term development potential. The proliferation of literature on pulmonary medicine delivery, especially in recent years, shows increased interest. Aerogels come in various technologies and compositions, but any aerogel used in a biological system must be constructed of a material that is biocompatible and, ideally, biodegradable. Aerogels are made via "supercritical processing". After many liquid phase iterations using organic solvents, supercritical extraction, and drying are performed. Moreover, the sol-gel polymerization process makes inorganic aerogels from TMOS or TEOS, the less hazardous silane. The resulting aerogels were shown to be mostly loaded with pharmaceutically active chemicals, such as furosemide-sodium, penbutolol-hemisulfate, and methylprednisolone. For biotechnology, pharmaceutical sciences, biosensors, and diagnostics, these aerogels have mostly been researched. Although aerogels are made of many different materials and methods, any aerogel utilized in a biological system needs to be made of a substance that is both biocompatible and, preferably, biodegradable. In conclusion, aerogel-based pulmonary drug delivery systems can be used in biomedicine and non-biomedicine applications for improved sustainability, mechanical properties, biodegradability, and biocompatibility. This covers scaffolds, aerogels, and nanoparticles. Furthermore, biopolymers have been described, including cellulose nanocrystals (CNC) and MXenes. A safety regulatory database is necessary to offer direction on the commercialization potential of aerogelbased formulations. After that, enormous efforts are discovered to be performed to synthesize an effective aerogel, particularly to shorten the drying period, which ultimately modifies the efficacy. As a result, there is an urgent need to enhance the performance going forward.

Insight into compression-rebound behavior of lignocellulose-derived aerogel through finite element modeling based dynamic impact simulation

In this study, lignocellulose-derived aerogel (LA) with compression-rebound was synthesized from liquefied wood through sol-gel polymerization, aging and freeze-drying process. The results presented a gradual increase in the compressive strength, flexural strength, and maximum decomposition temperature of the LA sample with prolonged aging time from 3 to 10 h, demonstrating excellent elasticity and thermal stability. After more than 10 h, the bending strength began to decrease, indicating that the material’s rigidity was greater than its elastic toughness at this time. A nonlinear viscoelastic constitutive model based on the Ogden function and parallel rheological framework showed very high correlation with experimental measurement results, and also demonstrated admirable mechanical properties. These predictions can provide an effective approach for the application of LA in buffer packaging.

Exploring nanoarchitectonics and optical properties of PAA-ZnO@BCP wide-band-gap organic semiconductors

This work reports the formation of polyacrylic acid (PAA)—zinc oxide (ZnO)—bromocresol purple (BCP), (PAA-ZnO@ (0.00–0.01) BCP wide-bandgap organic semiconductors deposited onto glass substrates via a sol–gel polymerization process. These semiconductor films were deposited on glass substrates using a spin coating and then dried at 60 °C. The PAA-ZnO film appeared to be of amorphous phase, and films loaded with BCP revealed semicrystalline behavior. The surface of the films exhibited adherence and extended grains. The hydrogen bonds formed between PAA-ZnO and the BCP dye within the PAA-ZnO@BCP films was performed using FTIR-spectroscopy. The prepared nanocomposites demonstrate an indirect band transition which is affected slightly by adding ZnO and BCP dye. Optical parameters such as the absorption coefficient, the refractive index, the dielectric constant, optical conductivity, optical depth, and optical electronegativity of the prepared nanocomposites were studied as functions of incident light energy (wavelength). The PAA carbonyl group n-π* transition and BCP aromatic ring π-π* transitions were detected at about 285 (for all samples) and 432 nm (for BCP loaded samples), respectively. The superior photoluminescence characteristics observed in the BCP/PAA-Zn films excited with a wavelength of 250 nm indicated the successful loading of the BCP dye during the self-aggregation of the PAA-Zn film.

Polyacrylic acid tethered onto the surface of vinyl functionalized silica nanoparticles for flexible hydrogel electrolytes of sodium ion hybrid supercapacitors

Hydrogel electrolytes, where water solvents and salts are confined in the porous networks of polymeric or inorganic solids, are attractive because they can resolve technical challenges of liquid electrolytes such as leakage, water decomposition, and mechanical instability. Herein, we demonstrate polyacrylic acid tethered onto the surface of vinyl functionalized silica nanoparticles (PAA-VSNP) hydrogel electrolytes through a sol-gel and radical polymerization process. The synthesis chemistry, the associated chemical structure, and the morphology of PAA-VSNP hydrogel electrolytes were comprehensively characterized analyzing FTIR, XPS and 13C and 29Si solid-state MAS NMR spectroscopies. The resulting PAA-VSNP hydrogel electrolytes were mechanically stable as verified by the stretchability up to 1122.75% of original length as well as ionically conductive as demonstrated by higher ionic conductivity of 20.23 mS cm−1 and lower activation energy of 0.106 eV than those of PVA counterparts. Integrating this PAA-VSNP hydrogel electrolytes with activated carbon and Na3V2(PO4)3/carbon composite and, flexible sodium ion hybrid supercapacitors (AC//PAA-VSNP //NVP@C SHSC SHSC) full cells could be fabricated. The as-fabricated AC//PAA-VSNP//NVP@C SHSC achieved a long-term cyclability over 4000 cycles and flexibility, delivering the larger energy and power densities 86.95 W h kg−1 and 19.94 kW kg−1 than those of AC//PVA//NVP@C and other works using hydrogel electrolytes.

Expansion of Nanosized MgSiO3/Chitosan Nanocomposite Structural and Spectroscopic for Loading Velosef by Nanomaterial Intervention

The aim of this study is to investigate the effect of different doses of Velosef in magnesium silica/chitosan nanocomposite in terms of structural, morphology, optical properties, and bioactivity. Loading Velosef in fine-sized magnesium silica/chitosan is an efficient engineering approach for drug delivery. The sol-gel process was used to prepare magnesium silica fine-sized before being blended into chitosan matrix, which acts as a potential morphogenetic biomaterial. The Velosef/magnesium silica/chitosan nanocomposites were characterized by XRD, TEM, SEM, FTIR, UV-absorption, and antimicrobial studies. The XRD was characteristic the crystallinity degree of the MgO-SiO2/chitosan/Velosef nanocomposites with a three maximum peaks at 26.37°, 33.34o, 36.9°. FTIR results indicated the structural change occurred with the Velosef sol-gel polymerization process. UV-absorbance reveals that the MgO-SiO2/chitosan nanocomposite appeared a high performance for loading Velosef at two absorption bands at 253 and 347 nm. The MgO-SiO2/Chitosan/Velosef nanocomposites showed considerable antimicrobial activity in opposition to the tested representative microorganisms. The maximum antimicrobial activity was obtained with MgO-SiO2/Chitosan against both Escherichia coli and Candida albicans (37 mm), while the minimum antimicrobial activity (30 mm) was recorded against B. mycoides and E. coli with control.

Monolithic Carbon Spherogels as Freestanding Electrodes for Supercapacitors

This study presents a direct application for freestanding and monolithic carbon spherogels, which are highly porous carbon aerogels solely composed of hollow nanospheres, as binder-free electrode materials for supercapacitors. By applying polystyrene nanospheres as templating agents in the size range of 277–907 nm and concentrations from 1.5 to 12 wt % in the sol–gel polymerization process of resorcinol–formaldehyde, we can distinctly tailor the hollow spheres’ pore arrangement and thickness of the microporous carbon walls. Furthermore, the required synthesis conditions for mechanically processable (sliceable) carbon spherogels are explored. Following physical activation with carbon dioxide, only 277 nm templated samples, featuring one thin-walled (<20 nm) and one thick-walled (>60 nm) variant, retain a freestanding bulk constitution and hence are suitable for the application as binder-free electrodes. The electrochemical evaluation demonstrates the advantage of hollow carbon sphere aerogels in comparison to conventional carbon aerogels with respect to capacitance, particularly at high scan rates. The analysis of the electrolyte diffusion kinetics and the network morphology after 10,000 charge/discharge cycles reveals the necessity of wall thickness optimization. Thick-walled variants are favored due to a much higher rate capability of 30 kW kg–1 compared to 10 kW kg–1). Additionally, a post-mortem TEM analysis reveals the loss of a central cavity and sphere degradation in thin-walled samples.

A strategy of utilizing Cu2+-mediating interaction to prepare magnetic imprinted polymers for the selective detection of celastrol in traditional Chinese medicines

In this work, a novel strategy to prepare molecularly imprinted polymers (MIPs) functionalized magnetic carbon nanotubes (MCNTs) via a facile sol-gel polymerization by adopting Cu2+-mediating interaction was presented for selective recognition of celastrol (Cel), in the traditional Chinese medicines (TCM). Firstly, template Cel, 3-aminopropyltriethoxysilane (APTES) as monomer and Cu2+ (co-monomer) were mixed to form a self-assembled pre-complex, in which Cu2+ could coordinate with Cel. Meanwhile, APTES plays a role of bridge between APTES and Cel. Secondly, carboxyl modified MCNTs as substrate was added into the pre-complex solution. After that, a multi-step sol-gel polymerization process was occurred in the presence of tetraethylorthosilicate as cross-linker and acetic acid as catalyst. Finally, MIPs layer was formed on the surface of the MCNTs (Cel-MIPs@MCNTs) after the removal of template with methanol/acetic. The morphology and structure of Cel-MIPs@MCNTs was investigated by various characterization techniques. The adsorption performance of Cel-MIPs@MCNTs to Cel was illustrated by kinetic, isothermal and selective binding experiments. The results displayed that the Cel-MIPs@MCNTs possessed fast kinetic equilibrium time (40 s), high adsorption capacity (13.35 μg mg−1), good imprinting factor of 3.41, and high magnetic responsivity (44.38 emu·g-1), which can be used as an ideal adsorbent for rapid isolation and enrichment of target analytes. A selective and sensitive method based on Cel-MIPs@MCNTs coupling with HPLC was developed for Cel determination including a wide linear range (0.15–200 μg mL−1) with correlation coefficient of 0.9998, a low limit of detection (0.05 μg mL−1). Furthermore, the applicability of Cel-MIPs@MCNTs was demonstrated to isolate and determine Cel in TCM samples with satisfactory recoveries ranged from 84.47% to 91.5% (RSD<5.35%). The results revealed that Cel-MIPs@MCNTs offer great potential as an adsorbent for selective and efficient isolation of Cel from complex TCM samples.

Inorganic Sol-Gel Polymerization for Hydrogel Bioprinting.

An inorganic sol–gel polymerization process was used as a cross-linking reaction during three-dimensional (3D) bioprinting of cell-containing hydrogel scaffolds. Hybrid hydroxypropyl methyl cellulose (HPMC), with a controlled ratio of silylation, was prepared and isolated as a 3D-network precursor. When dissolved in a biological buffer containing human mesenchymal stem cells, it yields a bioink that can be printed during polymerization by extrusion. It is worth noting that the sol–gel process proceeded at pH 7.4 using biocompatible mode of catalysis (NaF and glycine). The printing window was determined by rheology and viscosity measurements. The physicochemical properties of hydrogels were studied. Covalent functionalization of the network can be easily performed by adding a triethoxysilyl-containing molecule; a fluorescent hybrid molecule was used as a proof of concept.

Surpassing Robeson Upper Limit for CO2/N2 Separation with Fluorinated Carbon Molecular Sieve Membranes

Summary The CO2-philic properties of powdered fluorinated triazine frameworks make them promising candidates for fabrication of porous CO2 separation membranes. This is rarely reported because of lack of suitable synthetic approaches. Here, fluorinated membranes based on covalent triazine frameworks are prepared through a rational design of aromatic nitrile monomers containing fluorine and ether groups via a sol-gel polymerization process. The CO2 separation performance rises significantly with the fluorine content in the membrane. With functionalized triazine units, fluorine, and ether groups, these carbon molecular sieve membranes obtained after pyrolysis exhibit intrinsic ultra-micropores, high surface areas and excellent thermal stability under air. Excellent CO2 permeability and CO2 to N2 selectivity surpassing the Robeson upper bound are achieved. Our general design and synthesis protocol allow an easy access to fluorinated porous membranes, thus significantly expanding the currently limited library of CO2-philic and chemically stable membranes for highly efficient CO2 separation.

Preparation and characterization of organic-inorganic hybrid ZrOC/PF aerogel used as high-temperature insulator

Organic-inorganic hybrid ZrOC/PF aerogel composite is successfully prepared via one sol-gel polymerization process, using PF and ZrOC sols as precursor, respectively. SEM, BET, FT-IR, and XPS measurements are used to investigate the effect of the mass ratio of ZrOC to PF on physical, microstructure, and thermal properties of the composite aerogels. Results show that the aerogels exhibit relative low density (0.258–0.332 g/cm3), relative high compressive strength (0.32–1.40 MPa), and low thermal conductivity (0.0466–0.0660 W/m·K). SEM images demonstrated that the particles are composed of the tangled clusters of the PF and ZrOC and the particle size ranges from a dozen nm to tens of nm, up to several microns. XPS results indicate that elements C, O, and Zr in the samples are based on C–C and Zr–O valences band binding, respectively. The ZrOC/PF aerogel with excellent physical property and potential high-temperature resistance may be used in aerospace in the near future.

Environmental Topology and Water Availability Modulates the Catalytic Activity of β-Galactosidase Entrapped in a Nanosporous Silicate Matrix.

In the present work we studied the catalytic activity of E. coli β-Gal confined in a nanoporous silicate matrix (Eβ-Gal) at different times after the beginning of the sol-gel polymerization process. Enzyme kinetic experiments with two substrates (ONPG and PNPG) that differed in the rate-limiting steps of the reaction mechanism for their β-Gal-catalyzed hydrolysis, measurements of transverse relaxation times (T2) of water protons through 1H-NMR, and scanning electron microscopy analysis of the gel nanostructure, were performed. In conjunction, results provided evidence that water availability is crucial for the modulation observed in the catalytic activity of β-Gal as long as water participate in the rate limiting step of the reaction (only with ONPG). In this case, a biphasic rate vs. substrate concentration was obtained exhibiting one phase with catalytic rate constant (kcA), similar to that observed in solution, and another phase with a higher and aging-dependent catalytic rate constant (kcB). More structured water populations (lower T2) correlates with higher catalytic rate constants (kcB). The T2-kcB negative correlation observed along the aging of gels within the 15-days period assayed reinforces the coupling between water structure and the hydrolysis catalysis inside gels.

Solvent-resistant CTAB-modified polymethylsilsesquioxane aerogels for organic solvent and oil adsorption

In this work, we describe the successful synthesis of super-hydrophobic polymethylsilsesquioxane (PMSQ) aerogels with a porous network by a sol-gel polymerization process using methyltrimethoxysilane (MTMS) reactants with the addition of cetyltrimethylammonium bromide (CTAB) surfactants. The specific surface area, pore size and hydrophobicity of the CTAB-modified PMSQ aerogels were investigated for different amounts of CTAB doping. The specific surface areas of the pristine and CTAB-modified PMSQ aerogels with C/M molar ratios of 0.001, 0.002 and 0.004 were 491, 301, 342 and 298m2/g, respectively. The water contact angles of the CTAB-modified PMSQ aerogels with C/M molar ratios of 0.001, 0.002 and 0.004 were 166.38°, 165.62° and 166.43°, confirming the super-hydrophobicity of the CTAB-modified PMSQ aerogels. Compared to pristine PMSQ aerogels, the as-prepared CTAB-modified PMSQ aerogels exhibit more solvent-resistant properties in ethanol (EtOH) and n-hexane solvents. The as-prepared CTAB-modified PMSQ aerogels were further used for organic solvent and oil adsorption applications. Consequently, the as-prepared CTAB-modified PMSQ aerogels have great potential for organic solvent and oil adsorption in industrial applications.

New red-shade environmental-friendly multifunctional pigment based on Tb and Fe doped Y2Zr2O7 for ceramic applications and cool roof coatings

A new red-shade environmental friendly ceramic pigment with the general formula Y2−xTbxZr2−yFeyO7−δ [x = 0, 0.25 and y = 0.15, 0.25, 0.35] was prepared by a polymeric sol-gel process and after calcination at 1300 °C for 12 h. The solid solution range with defect fluorite structure was determined by XRD. The presence of terbium ions promoted the incorporation of iron ions in the structure. The evolution of the colour was studied by UV/Vis absorption measurements and CIELab chromatic coordinates were determined. The colour was related to the oxidation states of the terbium and iron ions studied by XPS and photoluminescence. Pigments presented the best chromatic coordinates when the amount of Fe(III) and Tb(IV) ions were higher. The sample with good red colouration (x = 0.25, y = 0.35) was tested with an industrial frit, presenting slightly better chromatic coordinates to those of the commercial ceramic pigment currently used. The pigment also showed an optimal NIR reflectance to be applied as “cool pigment” for roof isolation.

Investigation of microstructure and mechanical properties of novolac/silica and C/SiO2/SiC aerogels using mercury porosimetry method

Novolac/silica nanocomposite aerogels are prepared through the sol–gel polymerization process under a solvent saturated vapor atmosphere. The silica phase is extracted from rice husk ash in the form of silica xerogel powder. Nanocomposite aerogels are then fabricated through sol–gel polymerization of novolac resin in the presence of silica xerogel powder. These nanocomposite aerogels are then converted to carbon/silica and carbon/silica/silicon carbide nanocomposite aerogels using pyrolysis and carbothermal reduction processes at 800 and 1500°C, respectively. Mercury porosimetry method is used for the evaluation of microstructure and mechanical properties of fabricated hybrid nanocomposite aerogels. Mercury porosimetry analysis and scanning electron microscopy results confirmed that the Pirard and Washburn theories are valid for the evaluation of aerogels' pore size distribution. The buckling intrusion mechanism is studied for all polymeric and carbon nanocomposite aerogels below transition pressure. The effect of heat treatment on the microstructural properties is also investigated by mercury porosimetry analysis. The Young's modulus values are determined using mercury porosimetry data and compression results. Based on our results, the Young's modulus of hybrid nanocomposite aerogels is not necessarily related to the density of aerogels.

Molecular imprinting ratiometric fluorescence sensor for highly selective and sensitive detection of phycocyanin.

A facile strategy was developed to prepare molecular imprinting ratiometric fluorescence sensor for highly selective and sensitive detection of phycocyanin (PC) based on fluorescence resonance energy transfer (FRET), via a sol-gel polymerization process using nitrobenzoxadiazole (NBD) as fluorescent signal source. The ratio of two fluorescence peak emission intensities of NBD and PC was utilized to determine the concentration of PC, which could effectively reduce the background interference and fluctuation of diverse conditions. As a result, this sensor obtained high sensitivity with a low detection limit of 0.14 nM within 6 min, and excellent recognition specificity for PC over its analogues with a high imprinting factor of 9.1. Furthermore, the sensor attained high recoveries in the range of 93.8-110.2% at three spiking levels of PC, with precisions below 4.7% in seawater and lake water samples. The developed sensor strategy demonstrated simplicity, reliability, rapidity, high selectivity and high sensitivity, proving to be a feasible way to develop high efficient fluorescence sensors and thus potentially applicable for ultratrace analysis of complicated matrices.

Gas separation using sol–gel derived microporous zirconia membranes with high hydrothermal stability

A microporous zirconia membrane with hydrogen permeance about 5×10−8mol·m−2·s−1·Pa−1, H2/CO2 permselectivity of ca. 14, and excellent hydrothermal stability under steam pressure of 100kPa was fabricated via polymeric sol–gel process. The effect of calcination temperature on single gas permeance of sol–gel derived zirconia membranes was investigated. Zirconia membranes calcined at 350°C and 400°C showed similar single gas permeance, with permselectivities of hydrogen towards other gases, such as oxygen, nitrogen, methane, and sulfur hexafluoride, around Knudsen values. A much lower CO2 permeance (3.7×10−9mol·m−2·s−1·Pa−1) was observed due to the interaction between CO2 molecules and pore wall of membrane. Higher calcination temperature, 500°C, led to the formation of mesoporous structure and, hence, the membrane lost its molecular sieving property towards hydrogen and carbon dioxide. The stability of zirconia membrane in the presence of hot steam was also investigated. Exposed to 100kPa steam for 400h, the membrane performance kept unchanged in comparison with freshly prepared one, with hydrogen and carbon dioxide permeances of 4.7×10−8 and ~3×10−9mol·m−2·s−1·Pa−1, respectively. Both H2 and CO2 permeances of the zirconia membrane decreased with exposure time to 100kPa steam. With a total exposure time of 1250h, the membrane presented hydrogen permeance of 2.4×10−8mol·m−2·s−1·Pa−1 and H2/CO2 permselectivity of 28, indicating that the membrane retains its microporous structure.

Development of monolithic adsorbent via polymeric sol–gel process for low-concentration CO2 capture

Abstract The objective of this research was to develop a new high-performance CO 2 adsorbent with a simple method. Amine hybrid resorcinol–formaldehyde/silsesquioxane composite aerogel (AH-RFSA) was developed through polymeric sol–gel process and supercritical drying (SCD) technique. CO 2 adsorption performances of AH-RFSA in 1% CO 2 gas mixture (CO 2 + N 2 ) were investigated. A rise in adsorption temperature negatively affects the total CO 2 adsorption capacity of AH-RFSA. However, the useful adsorption capacity does not change with adsorption temperature. Water is more positive to useful CO 2 adsorption capacity than to total CO 2 adsorption capacity. The total CO 2 adsorption capacity achieved with the new adsorbent at 30 °C under dry and humid 1% CO 2 is 3.57 and 4.43 mmol/g, respectively. The useful CO 2 adsorption capacity for complete removal of CO 2 from 1% CO 2 is as high as 3.56 mmol/g. The adsorbent preparation method is inspiring and its resulting adsorbent is exceptional in capacity and regenerability.

Process efficacy and novelty of titania membrane prepared by polymeric sol–gel method in removal of chromium(VI) by surfactant enhanced microfiltration

Abstract Micellar enhanced microfiltration (MEMF), a surfactant-based separation process, is promising in removing multivalent metal ions from aqueous solutions. The choice of the membrane is very important in this process. MEMF of chromium(VI) from aqueous solution was studied using cetylpyridinium chloride (CPC) as the cationic surfactant. A simple preparation method for the porous ceramic membrane was developed from nanocrystalline titania (TiO2) powder using polymeric sol–gel process. Further the titania membrane from the powder was sintered at 450 °C for 1 h to obtain a stable structure. The membrane morphology and the crystal structure were analyzed by SEM and XRD. The effect of calcination temperature on membrane porosity was also investigated using mercury porosimetry. The mean pore size, porosity and pure water permeability of membrane were 0.58 μm, 0.32 and 1049 l/(m2 h bar), respectively. These membranes were used in a batch microfiltration system for removal of hexavalent chromium from aqueous solution. Effects of various parameters such as pH, pressure and surfactant to chromate ratio (CPC/Cr) on microfiltration performance were studied. The removal of chromium(VI) was found to be highly dependent on pH of the feed solution. The surfactant to chromate ratio (CPC/Cr) of 2.5 which was below the CMC was found to be ideal for 99% removal of chromium(VI) at initial chromate concentration 100 mg/l. Titania membranes can be effectively used for treatment of chromium containing wastewaters as an alternative. The membrane synthesis and its use in chromate removal are new findings. Other ions can be effectively removed by titania membranes through proper synthetic processes.

Fabrication of mesoporous TiO2 membranes by a nanoparticle-modified polymeric sol process

A straightforward synthesis of crack-free mesoporous titania membrane on a macroporous support without intermediate layers by a nanoparticle-modified polymeric sol–gel process is reported. TiO2 nanoparticle (Degussa P25) was dispersed into the prepared sol to toughen the formed gel. This helped to avoid the cracking of membrane during the drying and early stage of sintering, particularly when the sol–gel transformation occurred on a substrate with an uneven surface. The results of X-ray diffraction and Brunauer–Emmett–Teller analyses show that the nanoparticle doping did not significantly affect the particle size of TiO2 nanocrystals; however, it slightly broadened the pore size distribution because it has a larger particle size compared to the prepared materials. The sols with and without P25 nanoparticle were subsequently dip-coated on a support with average pore size of 150nm, thus formed a mesoporous membrane layer after drying and sintering processes. An integrated, crack-free mesoporous TiO2 membrane layer was obtained by this method, while the membrane prepared with the original sol developed a few cracks. Further, the filtration experiment showed that the prepared membrane had a high flux, and the membrane with nanoparticle modification delivered better separation performance by rejection of dextran.

Electrochemical Behaviour of Surface Modified SiO&lt;SUB&gt;2&lt;/SUB&gt;-Coated LiNiO&lt;SUB&gt;2&lt;/SUB&gt; Cathode Materials for Rechargeable Lithium-Ion Batteries

Pristine and SiO2-coated on layered LiNiO2 nanoparticles were synthesized by polymeric sol gel process using metal nitrate precursors at 600 degrees C for 10 h. Effect of SiO2 coating on the structure and electrochemical properties of the LiNiO2 cathode material was investigated by using XRD, SEM, Cyclic voltammetry and Charge-discharge techniques. X-ray powder diffraction analysis of SiO2-coated LiNiO2 revealed that the coating did not affect the crystal structure and the R-3m space group of the cathode materials compared to uncoated LiNiO2. Surface morphology of LiNiO2 and silica coated LiNiO2 powder materials were characterized by using SEM studies. The galvanostatic charge/discharge studies of the pristine and silica coated LiNiO2 positive materials were found at 0.5-C rate in the potential range between 3-4.5 V, Silica coated positive electrode materials have improved charge/discharge capacities. Cyclic voltammetry studies have revealed that, short range deintercalation/intercalation process of Li+ ions and the 2 wt.% relatively narrower peaks with less peak separation. 2 wt.% of SiO2-coated LiNiO2 positive material met the structural stability, high reversible capacity and high electrochemical performances.