The lithium sodium borosilicate jadarite, LiNaSiB3O7(OH), was first identified in 2007 in the Jadar basin, Serbia, where it forms the principal ore mineral of one of Europe's largest Li deposits. We report the successful application of the dry-gel conversion technique (DGC) to synthesise a jadarite analogue, via a dry-gel precursor made using sol-gel synthesis and the inclusion of the structure directing agent tetraethylammonium hydroxide (TEAOH). Pawley refinement of powder X-ray diffraction (PXRD) data collected on the synthetic sample was carried out using a monoclinic unit cell in space group P21/c (Whitfield et al., 2007), and gave refined unit cell parameters of a = 6.824(3) Å, b = 13.882(5) Å, c = 7.735(3) Å and β = 124.37(1)° (Rwp = 9.22). Inductively-coupled plasma optical emission spectroscopy (ICP–OES) on the synthetic sample confirmed an empirical formula of Li1.07Na1.40Si0.79B3O7.32(OH), based on three B atoms per formula unit (apfu). The synthetic product was found to be deficient in Si compared to natural jadarite from analysis of PXRD and ICP–OES data. Fourier-transform infrared spectroscopy (FTIR) showed that synthetic jadarite has peaks at 1415 and 1342 cm–1 and between 1180 and 900 cm–1, which are attributed to the presence of trigonal (BO3) and tetrahedral (BO4) borate groups characteristic of the natural jadarite structure, as well as a broad peak at 3441 cm–1 due to the presence of residual TEAOH. Scanning electron microscopy showed similarities in the morphologies between synthetic and natural jadarite particles.

The modification of montmorillonite with metallic species affects directly its crystalline structure, texture, porosity, and surface. The interaction of the metallic molecules with the clay matrix, derived from the modification pathway and the characteristics of the adsorbate, modifies the physicochemical properties of montmorillonite, enabling the creation of materials with varied characteristics to be used both as catalysts and adsorbents. Small amounts of metallic species can confer various structural and physicochemical characteristics on the same montmorillonite matrix, depending on the metal incorporated. The objective of the present study was to create an acid-base catalyst based on montmorillonite K10 (K10 Mnt), modified with Ti, Ce, and Ni, for the catalytic esterification of acetic acid and penta-1-ol. K10-Mnt was modified using particles of Ti and of Ti modified with Ce and Ni. The effect of the inclusion of Ti and modified Ti species on the transformation of the physicochemical properties of the K10 Mnt and their contributions to the catalytic esterification syntheses were investigated. Samples were characterized by scanning electron microscopy coupled to an energy-dispersive X-ray spectroscopy system (SEM-EDS), powder X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), physisorption of N2 at 77 K (BET and BJH), and thermogravimetric analysis (TGA-DTGA). Finally, the original and modified K10 Mnt samples were tested for their catalytic esterification of acetic acid and penta-1-ol in the liquid phase.

Hybrid coatings for cavitation erosion protection of aluminum alloys, have been developed, based on a sol-gel process and applied by the dip coating technique. This work aims to investigate established hybrid sol-gel coatings synthesized using organically modified silicon precursor 3-methacryloxypropyltrimethoxysilane (MAPTMS) mixed with zirconium (IV) propoxide. In the present research, the established baseline coatings were modified by adding different concentrations (1%, 1.5% and 2%) of cross-linkable hexamethylenediisocyanate (HMDI) diluted in 60% ethanol. The influences of the amount of crosslinker incorporated into the coatings on abrasion, corrosion and cavitation erosion protection were studied. The hydrophobic nature, thermal and electrochemical properties of the coatings were evaluated using Water Contact Angle (WCA), Differential Scanning Calorimetry (DSC), Open Circuit Potential (OCP) and Potentiodynamic polarization (PDS) techniques. Furthermore, cavitation erosion and abrasion tests were completed on all coatings and rankings of these were produced based on mass loss measurements and derived mean depth of erosion.

A simple model system towards an impedance-probing strain sensor based on conducting tough hydrogels is demonstrated. A poly(acrylamide) hydrogel, cross-linked with N,N’-methylene-bis(acrylamide) was contacted with carbon fibres for electrical impedance analysis. The conductivity of the salt-containing hydrogel was determined to be 114 ± 10 mS/cm. Upon stretching the hydrogel samples to their fourfold initial length, the impedance response increased according to a power law. This was used to establish a sensing equation for the relation between the resistive component of the impedance signal and the applied mechanical strain under tension. This work contributes to the development of highly stretchable and soft strain sensors for applications in soft robotics.

Nanoparticles are often used for both metals and non-metals, in cosmetics, home appliances, electrical products, as well as paints and inks. Nanoparticles are commonly produced by the vapor phase method or the liquid phase method. However, it is still difficult to produce nanoparticles with complicated shapes, such as raspberry-shaped particles. In this study, we demonstrated that nano-raspberry particles can be made by coating the surface of the small- and the large-sized silica nanoparticle with a reactive, chemically adsorbed, monomolecular film and then by bonding the smaller nanoparticles to the surface of the larger nanoparticle. Furthermore, by preparing a fractal surface structure on a flat substrate surface, a super-water and oil repellent surface, which can potentially improve the application performance, was successfully produced.

Edible devices are an emergent technology and in this paper the simplicity and efficacy that poly(acrylic acid)/calcium hydroxide possess in creating a pH sensitive ingestible actuator which responds to acidic environments such as gastric fluid is demonstrated. It was found that poly(acrylic acid)/calcium hydroxide hydrogels exhibit reversible actuation upon submerging in 0.1 M sodium citrate for 2 hours. Our results show that these hydrogels can restore their compressive stress to 0.19 ± 0.06 MPa, swelling ratio to 26 ± 2 and volume to 56% ± 3% of its original volume. This work offers new possibilities for developments in a variety of fields such as drug delivery, 4D printed materials, soft robotics and edible devices.

In this work, strongly blue emitting Ce3+-activated BaAl2O4 nanophosphors were successfully synthesized by a sol–gel technique. The crystal structure, morphology, and microstructure of the nanophosphors have been studied by X-ray powder diffraction, field emission scanning electron microscopy, and high-resolution transmission electron microscopy. The photoluminescence spectra show the impact of concentration variation of Ce3+ on the photoluminescence emission of the phosphor. These nanophosphors display intense blue emission peaking at 422 nm generated by the Ce3+ 5d → 4f transition under 350 nm excitation. Our results reveal that this nanophosphor has the capability to take part in the emergent domain of solid-state lighting and field-emission display devices.

Due to their excellent properties, aerogel has attracted the attention of the scientific community to use it in the biomedical area as a drug delivery system. This work reports on the synthesis and characterization of ZrO2 aerogels and cryogels obtained by the sol-gel method. The influence of different cetyltrimethylammonium bromide (CTAB) and the type of drying on structural, morphological and texture properties of ZrO2 aerogels and cryogels was investigated. SEM images reveal that a porous interconnected three-dimensional network was formed into aerogels due to supercritical drying. Zirconia aerogel sample has a specific surface area (SBET) larger than zirconia cryogels. Therefore, our results indicate that zirconia aerogel is an adequate material for applications in drug delivery systems.

Hybrid organic-inorganic semiconducting interfaces have attracted attention in photodiodes and field-effect transistors (FETs) due to the realization of intrinsic p-n junctions and their mechanical flexibility. With the difficulty of developing high-mobility n-type organic semiconductors due to the necessity of low LUMO levels and ambient environment stability, solution processable inorganic materials are an excellent alternative. ZnO is an intrinsic n-type semiconductor which is non-toxic and sol-gel processable, creating avenues for film patterning and fully solution processed devices. We report the improvement of electron mobilities in ZnO FETs through simple UV-Ozone processing which reduces lattice defects within the film and at the SiO2/ZnO interface. Treated ZnO films yield electron mobilities close to 10-2 cm2/Vs and on/off current ratios of 104 while non-treated films have mobilities on the order of 10-5 cm2/Vs and an order of magnitude lower on/off current ratios. Treated films also yield improved photoresponsivity and detectivity in hybrid ZnO-organic photodetectors.

Nanoparticles of titanium dioxide (TiO2), synthesized by the sonochemical technique, were mixed with different amounts of graphene oxide (GO), obtained by the improved method of Hummer, in order to modify their bandwidth. The TiO2/OG compounds were characterized using different techniques: X-ray Diffraction (XRD), transmission electron microscopy (TEM), Raman and UV-Vis-NIR spectroscopy. TiO2 bandgap decreased, with GO incorporation, from 3.2 to 2.72 eV when GO was present at 20 weigh percentage (TiO2/GO-20%). Photodegradation experiments of methylene blue (MB) were performed with the materials to verify their photocatalytic activity. At 40 minutes, the pure TiO2 degraded 48% of MB, whereas the compound TiO2/GO-20% degraded 88%, showing a good incorporation of both compounds and the improvement of TiO2 photocatalitic properties.

Oriented ZnO seed layers were deposited by three different techniques, namely, simple drop casting (DC), sol-gel derived dip coating (DPC) and spin coating of ball-milled ZnO powder solution(BMD) for the subsequent growth of vertically aligned ZnO nanorods along the substrate normal. X-ray diffraction (XRD) analyses revealed that ZnO(DC) seed layer exhibit the highest preferential c-axis texturing among the ZnO seed layers synthesized by different techniques. The Scanning Electron Microscopy (SEM) analysis evident that the morphology of ZnO seed layer surface is compact and coherently carpets the underlying substrate. ZnO nanorods(NRs) were then grown by hydrothermal method atop the ZnO seeded and non-seeded substrates grown by different techniques to elucidate the best ZnO seed layer promoting well-aligned ZnO Nanorods. The presence of c-axis oriented ZnO(DC) seeding layers was found to significantly affect the surface morphology and crystallographic orientation of the resultant ZnO NRs films. The optical band gap of ZnO(DC) seed and ZnO NRs were estimated to be 3.30 eV and in the range of 3.18 – 3.25 eV respectively by using UV-VIS-NIR diffuse reflection spectroscopy. The room temperature photoluminescence analyses revealed that nanostructured ZnO films exhibit a sharp near-band-edge luminescence peak at ∼380 nm consistent with the estimated optical band gap and the ZnO nanorod arrays are notably free from defect-related green-yellow emission peaks.

Sol-gel blends are created using a combination of a high refractive index (n∼2.4) TiO2 based sol-gel and a low refractive index (n∼1.5) SiO2 based sol-gel. The blends are prepared with different ratios of sol-gels and films are created using the spin coating method on silicon and ITO-on-glass substrates. The film thickness, refractive index, and dielectric constants of the resulting films are measured using profilometry, prism coupling, and LCR measurements, respectively. Results show that including more SiO2 based sol-gel in the initial mixture creates thicker films ranging from 1-7 μm, but results in lower refractive index and lower dielectric constants. This is consistent with expectations due to SiO2 having a lower refractive index and dielectric constant than titania over a range of wavelengths andfrequencies. The ability to fine tune the properties is explored.

Biodegradable material was prepared from cassava starch in combination with zinc oxide nanoparticles (ZnO NPs) to give the properties of microbial growth resistance, glycerin concentrations were varied to 5%, 10%, and 20% (w/v) for the study of the rheological properties. The nanoparticles were characterized by a spectrophotometer where an exciton peak at 370 nm was obtained. The different samples were subjected to a thermomechanical study through an AR-G2 hybrid rheometer, using a parallel plane geometry of 20 mm, a weak gel behavior is observed, it is a slimming material and it is thermostable, it is also established that the zinc oxide concentration nanoparticles do not affect the mechanical behavior of the material.

Technological advances in synthesis and preparation of aerogels have resulted in formulations that have the mechanical integrity (while retaining flexibility) to be utilized in a broad range of applications and have overcome the initial brittleness that this class of materials was once known for. Both structural and functional aerogels show a drop in performance when subjected to certain cyclic thermal or impact loading due to the wear and formation of cracks, which reduces their lifespan. Here we present the proof-of-concept of a computational toolset that connects the change in thermal profile to structural failure and degradation. In combination with an appropriate finite element (FEM) solver, we have developed a genetic algorithm that can reconstruct the size and shape of the defective region in silica aerogels given the temperatures from a sensor grid. Results show that a heatmap can be used as the foundation for reconstructing faults and defects in thermally insulating materials. Furthermore, the model developed in this study can be expanded to accommodate other material types. Experimental setup can used to benchmark and refine the computational toolset.

We describe the use of immobilized deoxyribonucleic acid (DNA) in a silica matrix as a biorecognition agent for the detection of albendazole sulfoxide (ASU), the primary metabolite of albendazole and a suspected teratogenic and embryotoxic agent. The biomaterial (DNA-containing gel) was synthesized by physical entrapment of salmon sperm in an inorganic silicate matrix by the sol-gel method. Functionality of the DNA-containing gel was evaluated by comparative offline frontal chromatography followed by HPLC analysis of ASU and caffeine (CAF, control) using DNA-containing gel and DNA-free gel. The DNA-containing gel showed relatively high specific retention for ASU, while CAF showed no retention using frontal analysis. We anticipate that the DNA-containing gel can be implemented to identify the interactions of DNA with other active pharmaceutical ingredients (APIs) and their metabolites in a readily available, sensitive and selective frontal chromatography experiment.

In this study, the spontaneous formation of hydrogels from a water-soluble and amphiphilic ABA-type block copolymer in an aqueous system was examined. The block copolymers were composed of poly(2-methacryloyloxyethyl phosphorylcholine) (MPC) as the B segment and poly(n-butyl methacrylate) (BMA) as the A segment. A two-step living radical polymerization of the corresponding monomers yielded a well-defined ABA-type block copolymer. By regulating the polymerization degree of each segment, the water solubility and amphiphilic natures of the resulting block copolymer could be controlled. The block copolymers spontaneously formed hydrogels when the composition of water in the medium increased to 80 vol% in the water/ethanol mixture. This was due to molecular aggregation of the block copolymers driven by the hydrophobic interactions between the poly(BMA) segments in the polymer. This hydrogel formation depended on the composition and polymerization degree of the MPC units. The poly(MPC) also showed good biocompatibility, thereby rendering the block copolymers applicable for the immobilization of biological components such as antibodies and enzymes and the encapsulation of cells under mild conditions.

This work reports the synthesis of undoped and alkali metal doped thermochromic vanadium dioxide thin films by sol-gel spin coating and subsequent low-temperature annealing at 450 °C in N2-H2 atmosphere. The effect of sodium and potassium on the phase transition temperature as well as on the solar modulations were investigated. A dopant concentration of 0.3 at% resulted in a reduction of the critical transition temperature (Tc) from 62 °C to 57 °C and 47 °C for the sodium and potassium doped films, respectively. Moreover, both dopants improved the solar modulations (ΔTsol) of the undoped VO2 films from 3.81 to 9.44 and 5.43 %, respectively.

This article aims to prepare high quality of TiO2 powder and study the effect of annealing temperature. TiO2 particles were synthesized by sol-gel method using titanium tetra chloride (TiCl4) as a precursor. The dried gel was annealed at temperatures of 500oC, 600oC, 700°C and 800 °C each for 4 hours. The as-prepared samples were further characterized using X-Ray diffraction (XRD), Scanning electron microscope (SEM), Energy dispersive X-ray Fluorescence spectrometer (EDX), XRD showed anatase structure after annealing and its diffraction scattering intensity indicated the improvement in the crystal structure quality of TiO2 as the temperature increases. SEM micrographs showed a randomly distributed and non-uniform cluster of TiO2 that has a size increase with annealing temperatures. EDX indicated stoichiometric chemical composition between Ti and O enhanced by annealing.

Mesoporous silicas were synthesized via a surfactant-templated sol-gel route using castor oil as the templating agent under acidic medium. The resulting silicas were subsequently amine functionalized with 3-aminopropyltriethoxysilane (NH2-MTS), [3-(2-aminoethylamino)-propyl]trimethoxysilane (NN-MTS), and [3-(diethylamino)propyl]trimethoxysilane(DN-MTS) to introduce surface basicity. Surface physicochemical properties were characterized by field emission gun scanning electron microscopy (FEGSEM), nitrogen porosimetry, X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and diffuse reflectance infrared fourier transform spectroscopy (DRIFTS). As-synthesised materials exhibit type IV adsorption-desorption isotherms characteristic of mesoporous structures. Clusters of spherical shaped materials were observed by FEGSEM, suggesting growth of silica occurs within colloidal dispersions. High-resolution N 1s XP spectra and DRIFT spectra confirmed the presence of amine groups in the organo-amine functionalised mesoporous silicas. The amine functionalised mesoporous silicas were active for the transesterification of tributyrin with methanol, with conversion found to increase from NH2-MTS< NN-MTS< DN-MTS.

PNIPAM hydrogels are widely studied materials which swell in a great extent in water and water like solvents (e.g. alcohols). The hydrophilic nature of PNIPAM networks is very attractive however it is an important disadvantage at the moment of encapsulating hydrophobic drugs, which minimize their use in other fields. In this work we studied the swelling in different solvent mixtures with water and also in pure nonaqueous solvents, some of them immiscible with water. Accordingly, PNIPAM gels swell strongly in highly polar solvents (e.g. chloroform) but it does not swell in slightly polar solvents (e.g. toluene). The main interaction between the solvent and the polymer chain seems to involve the hydrogen bonding with the amide group, according to the calculated Hansen parameters (δh). It is possible to swell the gel in binary or ternary mixtures containing toluene. In that way, non-polar substances can be loaded inside the gel to change its properties. As a proof of concept, polyaniline (PANI) solubilized in chloroform using camphorsulfonate as solubilizing counterion. The obtained nanocomposites become sensitive to pH changing color and conductivity when exposed to basic or acidic aqueous solutions.