Zirconium Propoxide Research Articles

Ultra-Low Shrinkage Hybrid Photosensitive Material for Two-Photon Polymerization Microfabrication

Investigations into the structuring by two-photon polymerization of a nonshrinking, photosensitive, zirconium sol-gel material are presented. This hybrid material can be photostructured even when it contains up to 30 mol % of zirconium propoxide (ZPO); by varying the material's inorganic content, it is possible to modify and tune its refractive index. The introduction of ZPO significantly increases the photosensitivity of the resulting photopolymer. The fabricated three-dimensional photonic crystal structures demonstrate high resolution and a clear band-stop in the near-IR region. In contrast to common practice, no additional effort is required to precompensate for shrinkage or to improve the structural stability of the fabricated photonic crystals; this, combined with the possibility of tuning this material's optical, mechanical, and chemical properties, makes it suitable for a variety of applications by two-photon polymerization manufacturing.

SANS investigation of PDMS hybrid materials prepared by gamma-irradiation

Gamma-irradiation from a 60Co source was used to prepare hybrid materials from a mixture of polydimethylsiloxane with tetraethylortosilicate and zirconium propoxide. The obtained materials are monolithic and transparent after drying in air. They had been previously characterized by thermal analysis, X-ray diffraction, Rutherford backscattering and elemental analysis. The present work reports a small angle neutron scattering study on a few samples of these materials to investigate their microstructure at the nanoscale. This study showed the presence of inorganic oxide regions with mass fractal structure, their size and fractal density increasing with the tetraethylortosilicate content. Although the presence of zirconium propoxide is required to obtain a stable hybrid material yet the increase in its content leads to less dense mass fractal oxide units. It was found that the structure of the oxide regions developed through a reaction-limited aggregation mechanism. The further addition of isopropanol in the sample preparation stage causes the inorganic fractal structure to extend over the whole sample.

Thermal analysis of hybrid materials prepared by γ-irradiation

Hybrid materials were prepared by γ-irradiation of a mixture of polydimethylsiloxane (PDMS), with tetraethylorthosilicate (TEOS) and zirconium propoxide (PrZr), using a 60Co γ source, without any addition of solvents. Thermogravimetry, differential scanning calorimetry and X-ray diffraction measurements showed that the obtained hybrids are amorphous materials of the nanocomposite type. The results highlighted the different influence of each of the metallic alkoxides on the hybrid structure. The material rupture temperature, associated with the degradation of the organic component, depends mainly on the TEOS content, whereas the inorganic component structural stability depends on the relative PrZr content in the alkoxides mixture.

Properties of zirconia-toughened-alumina prepared via powder processing and colloidal processing routes

Alumina–zirconia composites were prepared by two routes: powder processing, and colloidal processing. Unstabilised zirconia powder was added to alumina in 5 wt%, 10 wt% and 20 wt% quantities. For the colloidal method, zirconium(IV) propoxide solution was added to alumina powder, also in 5 wt%, 10 wt% and 20 wt% quantities. Additions of glacial acetic acid were needed to form stable suspensions. Suspension stability was verified by pH measurements and sedimentation testing. For the powder processed samples Vickers hardness decreased indefinitely with increasing ZrO 2 additions, but for colloidal samples the hardness at first decreased but then increased again above >10 wt% ZrO 2. Elastic modulus ( E) values decreased with ZrO 2 additions. However, samples containing 20 wt% zirconia prepared via a colloidal method exhibited a much higher modulus than the powder processed equivalent. This was due to the homogeneous dispersion of zirconia yielding a sample which was less prone to microcracking.

Fabrication and Characterization of Sol-Gel Derived PZT/WO<sub>3</sub> Ceramics

Lead zirconate titanate/tungsten oxide (PZT/WO3) ceramics were prepared from the powders synthesized by a modified triol sol-gel processing method. In this study, the starting materials used for synthesis of PZT-sol were zirconium (IV) propoxide, titanium (IV) isopropxide, lead (II) acetate trihydrate and 1,1,1,- tris (hydroxymethyl) ethane. To prepare PZT/xWO3 powders (where x = 0, 0.5, 1 and 3 wt%), nano-sized WO3 was ultrasonically dispersed and mixed with the PZT sol, dried and calcined at 600°C for 4 h. X-ray diffraction results indicated that fully crystallized powders were obtained. Phase characterization suggested that at high WO3 concentration, the reaction between PZT and WO3 occurred during the calcination process. To prepare PZT/xWO3 ceramics, the powders were pressed and sintered at 1100°C for 6 h. Phase characterization by XRD indicated that the content of WO3 significantly affected tetragonal-to-rhombohedral phase transition. Microstructure of thermally etched samples showed that increasing the content of WO3 decreased grain size of the ceramics.

Effect of Calcination Temperature on Phase and Morphology of Sol-Gel Derived PZTN Powders

Niobium doped PZT (PZTN) powder was prepared by a triol-sol-gel method from a mixture of lead (II) acetate trihydrate, 1,1,1-tris (hydroxymethyl), acetylacetone, titanium (IV) isopropoxide, zirconium (IV) propoxide and niobium (V) ethoxide and calcined at temperature ranging from 300-600oC for 2 h and 600oC for 4 h with a heating/cooling rate of 5oC/min. Thermal characteristics of the PZTN powders were studied using thermogravimetric/differential thermal analyses (TG/DTA). Phase formation in the powder was determined using X-ray diffraction analysis (XRD). Morphology of the PZTN powder was investigated by a scanning electron microscopy (SEM) and transmission electron microscopy (TEM). High purity perovskite structure of PZTN powder with a rhombohedral structure and a crystallite size 38 nm was obtained at the temperature of 600oC for 4 h dwell time. Well separated particles with uniform particle size distribution within 10-50 nm were also observed by TEM.

Effect of zirconium(IV) propoxide concentration on the thermophysical properties of hybrid organic-inorganic films

In this work, micrometer-thick organic-inorganic hybrid films are fabricated. A photothermal experiment is designed and conducted to characterize the thermophysical properties of hybrid films, as well as the thermal contact resistance between the film and substrate. The molecular cagelike or nanopores, which can strongly enhance the phonon scattering, are considered to be formed inside the films during fabrication. The first order estimation of the volume fraction of cavities and its effect on thermophysical properties are obtained. The effect of zirconium(IV) propoxide (ZPO) concentration on the thermophysical properties of hybrid films is also studied. The effective (measured) thermal conductivity and thermal effusivity of hybrid films are close to those of polymethyl methacrylate (PMMA) films, and are not significantly affected by the added ZPO, which is used to adjust the optic properties of films. The extracted bulk thermal conductivity of the hybrid films is close or smaller than that of bulk PMMA, and shows certain thermal conductivity reduction by the ZPO addition. The thermal effusivity study indicates that the response of the surface temperature change to an abrupt heat flux across the surface of hybrid films will be similar to that of PMMA films.

Fabrication of microfluidic devices using photopatternable hybrid sol-gel coatings

UV-patternable organic-inorganic hybrid sol-gel coating was used to develop microchannel on silicon and glass wafers by photolithography processing. The sol-gel coating was formed with 3-methacryloxypropyltrimethoxysilane (MPTS) as photosensitive component and zirconium propoxide as property modifier. In order to enhance the UV light efficiency during photolithography processing for glass substrates, a thin copper layer with thickness of 100–200 nm was deposited on one side of the glass wafer. The closed microchannels were formed by bonding of two developed surface channels of compensating patterns by wafer bonding technology. The bonding material is the same as the channel body ensuring a uniform surface property for the microchannels. A thin layer of about 2 μm was applied on the developed channels by spin coating. The depth of the surface channels on each wafer is about 10–12 μm, and the height of the closed channels is therefore in the range of 22–24 μm. Different microfluidic devices such as chaotic micromixers and microsplitters were fabricated.

Si and Zr based NBBS for hybrid O/I macromolecular materials starting by preformed zirconium oxo-clusters

In this study surface-functionalized zirconium oxoclusters (ZrNBB), formed by reaction between vinylacetic acid and zirconium propoxide, were chemically modified through condensation with siloxane groups, so that the core integrity of ZrNBB was preserved. The direct coupling between zirconium oxo-clusters and siloxane moiety was performed by co-polymerisation with vinyl trimethoxysilane (VTMS) with Zr:Si molar ratio 1:2 in air at room temperature and benzoyl peroxide (BPO) was used as an initiator to start radical polymerization. The polymerisation was studied by differential scanning calorimetry (DSC) and Fourier Transform Infra Red (FTIR) spectroscopy. 29Si and 13C liquid and solid state NMR analyses were performed in order to study the microstructure of the hybrid material and the role of the clusters in polymerization and condensation. Beyond this, shear storage modulus (G′) and loss modulus (G′′), were investigated by dynamical mechanical spectroscopy (DMS). The results indicated a great stability at high temperature without any viscous flow during glass transition.

Low Dielectric Constant Polyimide-Zirconium Nanocomposites with Improved Thermal Properties

Low-dielectric-constant (κ) polyimide films with thermal integrity and controllable mechanical strength have been prepared by covalently bonding zirconium complex with lysine to the main chains of polyimide. The presence of chemical bonds between polyimide (PI) and zirconium has great effect on the properties of polyimide films, especially on their thermal and dielectric properties. The dielectric constants of the resultant nanocomposites are lower due to the increased free volume and fewer polar Zr–O–Zr groups, and can be tuned by varying the molar ratio of zirconium(IV) propoxide, Zr(OPr)4, in the feed. The possibility of obtaining the kinetic parameters of a reaction from a heating rate dependence of DTA peak location, as well as the merits of different peak methods, were also discussed. The composition, particle sizes, and morphological effect of the Zirconium on nanoparticles were determined by the energy dispersive analysis of X-ray (EDAX), and scanning electron micrographs (SEM).

Influence of zirconium propoxide on the radical induced photopolymerisation of hybrid sol–gel materials

This study emphasizes the role of zirconium propoxide on the free-radical photopolymerisation of hybrid organic–inorganic material based on 3-methacryloxypropyltrimethoxysilane (MAPTMS). By means of atomic force microscopy in pulsed force mode and real-time Fourier-transform infrared spectroscopy, it is shown that the addition of zirconium complex in the hybrid sol–gel material leads to a well-polymerised and hydrophilic surface under UV-illumination. By contrast, sols without zirconium complex exhibit soft and sticky surfaces. The study also demonstrates an unexpected role of oxygen in the photopolymerisation process. Indeed oxygen is well-known being a strong inhibitor of the radical polymerisation. However, in the present case, it interacts with Zr(OPr)4 and participates in a positive way to the photochemical process. During the irradiation, radicals react with O2 to form peroxyl radicals that are generally inert towards the photopolymerisation. By using laser flash photolysis, it was proved that these radicals combine with zirconium propoxide to form new initiating species that contribute to further free-radical photopolymerisation.

Elemental and RBS analysis of hybrid materials prepared by gamma-irradiation

Hybrid materials have been prepared by gamma-irradiation of a mixture of polydimethylsiloxane silanol-terminated, and the alkoxides tetraethylortosilicate and zirconium propoxide, using a 60Co gamma source. No other chemicals were added to these precursors. Samples have been prepared with different concentrations of polymer and different mixtures of the metallic alkoxides. The obtained samples were heat-treated at several temperatures. The as prepared hybrids are monolithic and transparent. After heat-treatment in air at 650°C the material remained monolithic if they were prepared from a mixture with alkoxide content larger than that of the polymer, whereas those prepared from a mixture with larger content of polymer reduced to coarse grains. These results indicate that the hybrid material matrix can consist of either inorganic oxide in the former case with embedded polymeric crosslinked chains or a polymeric matrix in the latter case with embedded inorganic oxide domains. Elemental analysis showed that the carbon release originates initially from reactions between the alkoxides whereas at the higher temperature it results from the polymer degradation. RBS analysis showed that Si is present in the material with an almost constant relative concentration but Zr is not homogeneously distributed, presenting different relative concentrations on the top and bottom surfaces of the same sample, depending on the composition.

The microstructure and mechanical properties of Fe–Cu materials fabricated by pressure-less-shaping of nanocrystalline powders

The microstructure of Fe-40%wtCu nanocrystalline powders, prepared by mechanical alloying, was studied before and after the consolidation process. Pressure-less-shaping (PS) was used to consolidate the powders. The PS technique, similar to metal injection moulding (MIM), does not require external pressure in order to fill up the mould. The key factor of the process of consolidation is the use as binder a hybrid inorganic–organic monomer, formed by the reaction of zirconium propoxide and 2-hydroxy ethyl methacrylate. This type of monomer, mixed with the metallic powders, formed slurry having low viscosity, which was easily poured into mould. The binder stiffened upon polymerization. Some pieces were produced through debinding and sintering, both performed under inert atmosphere in order to avoid metal oxidation. Different microstructure and density were observed depending on the maximum sintering temperatures, ranging from 904 to 1,120 °C. In the sample sintered at 1,120 °C, the crystalline domains of the copper phase were of about 40 nm.

Effect of synthesis conditions on the pore structure and degree of heteroatom insertion in Zr-doped SBA-15 silica-based materials prepared by classical or microwave-assisted hydrothermal treatment

Zirconium doped mesoporous SBA-15 materials with initial Si/Zr ratios of 10 and 20 have been prepared under microwave-hydrothermal conditions using a non-ionic triblock copolymer surfactant as structure-directing agent, as well as zirconyl chloride and zirconium propoxide as two zirconium sources. The effect of a short (5 min) and long (1.5 h) sol ageing time on the degree of heteroatom incorporation was tested. Changes in the mesopore size and arrangement were monitored with the aid of powder X-ray diffraction (XRD) and gas nitrogen adsorption/desorption at 77 K. The degree of Zr incorporation into the silica framework of the final product was inferred from the analysis by energy-dispersive X-ray spectroscopy and compared with the starting value based on the amount of zirconium added to the reaction mixture. In the case of samples with the lowest initial theoretical molar ratio, the synthesis conditions did not affect the degree of heteroatom incorporation into the silica framework and all zirconium could be introduced under the conditions applied. The structure of materials was strongly dependent on the conditions used, and a more regular pore arrangement was obtained for longer maturation stages. The classical hydrothermal synthesis did not result in a significantly higher efficiency in the heteroatom insertion, though microwave-assisted treatment yielded materials with thicker pore walls. Further increase in the amount of zirconium added to the initial gel did not contribute to a greater heteroatom loading in the final product under microwave conditions.

Hybrid PDMS–Silica–Zirconia materials prepared by γ-irradiation

Hybrids are a class of materials that enable the integration of organic and inorganic characteristics at the molecular level in a single material. In this way materials with unusual optical, mechanical or even bioactive properties are obtained, which are especially suitable for applications as sensors, non-linear optical (NLO) materials, lasers, selective membranes, catalysts and protective coatings. Sol–gel processing is often used for the preparation of hybrids, usually through the alkoxides method that leads to high purity products at relatively low temperatures. The authors have developed a new method for the preparation of these materials based on gamma irradiation of the precursors mixture. The precursors used are polydimethylsiloxane (PDMS), tetraethylortosilicate (TEOS) and zirconium propoxide (PrZr). The irradiations were performed using the 60Co source at the Portuguese Gamma Irradiation Facility (UTR) located in the ITN campus at Sacavém. The materials at room temperature are macroscopically transparent, relatively flexible and amorphous. The details of the preparation of these hybrid materials by gamma irradiation are presented.

Dynamic dielectric response of PLZT-P(VDF/TFE) nanocomposites

Dynamic dielectric relaxation of polymer P(VDF/TFE)(0.98/0.02) loaded with lead lanthanum zirconate titanate (Pb0.92La0.08)(Zr0.65Ti0.35)O3(PLZT 8/65/35) ceramic nanopowders was studied in the frequency range from 100 Hz to 1 MHz and at temperatures from 100 K to 450 K. The PLZT nanopowders were prepared by the sol-gel method using: lead(II)acetate trihydrate, lanthanum acetate hydrate, zirconium(IV)propoxide and titanium(IV)propoxide. The crystallization process of PLZT powders was monitored by means of XRD analysis (Philips PW 3710) using Cu-Kα radiation in the range 20° ≤ 2Θ ≤ 60°. The powders were analyzed before and after burning of the organic remains. The morphology observations of the powders were made using Hitachi S-4700 scanning electron microscope (SEM), and the grain size distributions were measured on a Zetasizer Nano ZS by the DLS method. The PLZT-P(VDF/TFE) composite samples of 0-3 connectivity were prepared from ceramic and polymer powders by the hot-pressing method. The volume fraction of the ceramics Θ amounted 0.1, 0.15 and 0.2. The dielectric response of the ceramics-polymer composite was found as a combination of the responses of pure polymer and the ceramics: (i) the addition of the PLZT ceramics increases the value of the dielectric permittivity ϵ, (ii) the composite shows the maximum of the permittivity coming from the PLZT ceramics, (iii) the dielectric absorption spectrum of the composites is dominated by the α-relaxation in pure polymer.

Sol–gel processing of drug delivery zirconia/polycaprolactone hybrid materials

Poly(epsilon-caprolactone) (PCL 6, 12 and 24 wt%) and zirconium (ZrO(2)) organic-inorganic hybrid materials have been synthesized by the sol-gel method from a multicomponent solution containing zirconium propoxide [Zr(OC(2)H(7))(4)], poly(epsilon-caprolactone) (PCL), water, chloroform (CHCl(3)). Sodium ampicillin was incorporate in the hybrid materials to verify the effect as local controlled drug delivery system. The structure of interpenetrating network is realized by hydrogen bonds between Zr-OH group (H donator) in the sol-gel intermediate species and carboxylic group (H-acceptor) in the repeating units of the polymer. The presence of hydrogen bonds between organic/inorganic components of the hybrid material was proved by FTIR analysis. The morphology of the hybrid material was studied by scanning electron microscope (SEM). The structure of a molecular level dispersion has been disclosed by atomic force microscope (AFM), pore size distribution and surface measurements. The bioactivity of the synthesized hybrid material has been showed by the formation of a layer of hydroxyapatite on the surface of PCL/ZrO(2) samples soaked in a fluid simulating the composition of the human blood plasma. Release kinetics in a simulate body fluid (SBF) have been subsequently investigated. The amount of sodium ampicillin released has been detected by UV-VIS spectroscopy and SEM. The release kinetics seems to occur in more than one stage. HPLC analysis has also been taken to ensure the integrity of ampicillin after the synthetic treatment.

Comparative properties of ternary oxides of ZrO 2–TiO 2–Y 2O 3 obtained by laser ablation, magnetron sputtering and sol–gel techniques

Thin films of ternary oxides of zirconium (Zr), yttrium (Y) and titanium (Ti) were obtained by the sol–gel, magnetron sputtering and laser ablation techniques. Zirconium propoxide, titanium isopropoxide and yttrium nitrate hexahydrate reagents were used as precursors in the sol–gel process. The Zr/Ti and Zr/Y molar ratios have been controlled by varying the precursors and surfactant concentration. The obtained gels were supported by dip coating on α-alumina supports, dried at 373 K and calcinated at 873 K. The powders obtained after the removal of carbon residuals were subsequently pressed and calcinated for using as targets for the magnetron sputtering and pulsed laser deposition techniques. The chemical composition was determined by Auger Electron Spectroscopy. The surface topography was investigated by Atomic Force Microscopy, while the crystallinity was evaluated from X-ray diffraction. The electrical response of the deposits to nitrogen oxides (NO x) toxic gas is discussed according to the experimental conditions.

Synthesis of Nanocrystalline Zirconia Using Sol−Gel and Precipitation Techniques

Nanocrystalline zirconia samples having predominantly tetragonal crystalline phase were synthesized using sol−gel and conventional precipitation techniques from zirconium hydroxide obtained by the hydrolysis of both zirconium propoxide and zirconium oxychloride precursors. Thermal drying of zirconium hydroxide gel in an oven (110 °C, 12 h) results in lower crystallite size (11−13 nm) as compared to drying under vacuum (50 mbar, 70 °C), which shows higher crystallite size (20−21 nm) during both sol−gel and conventional precipitation synthesis. The progressive transformation of tetragonal to monoclinic phase of zirconia with increasing calcination temperature was observed to be related to the critical crystallite size and lattice strain. Sol−gel synthesis was found to be advantageous because of the stabilization of tetragonal phase at higher temperature, whereas complete phase transformation was observed in the samples prepared by precipitation method at 600−700 °C temperature. Sol−gel synthesis resulted in...

Effect of Mixed Sol‐Gel Precursors on the Metal‐Oxo Phase Within a UV‐Curable Silicone Hybrid Material

AbstractSummary: An inorganic hybrid material was produced using a polysiloxane binder and metal‐oxo‐clusters which were derived from sol‐gel precursors. The continuous phase is composed of an elastomeric polysiloxane functionalized with cycloaliphatic epoxide groups. Pendant alkoxy silane groups serve as a coupling agent to form a network between the metal‐oxo‐clusters and the crosslinked polysiloxane. Methyl, cyclopentyl, and cyclohexyl substituted polysiloxanes were formulated with a variety of sol‐gel precursors (tetraethylorthosilicate oligomers, titanium(IV) iso‐propoxide, zirconium(IV) propoxide, and zinc acetate). Phase‐modulated FT‐IR, X‐ray photoelectron spectroscopy, solid state 29Si NMR, and solid state 13C NMR were used to investigate the internal structure of the mixed metal‐oxo/silicon‐oxo colloids prepared within the cured polysiloxane matrix. Results indicate that the cycloaliphatic groups inhibit the complete hydrolysis and condensation of the pendant triethoxysilane group and reaction of the sol‐gel precursors. Analysis also indicated that the metal‐oxo‐clusters were comprised of mixed species of sol‐gel precursors resulting in hetero‐bonded (SiOMetal) colloids.Possible network compositions of the cured material (a) specific metal‐oxo‐clusters, (b) hetero‐bonded metal‐oxo‐clusters, and (c) core/shell type metal‐oxo‐cluster configuration.magnified imagePossible network compositions of the cured material (a) specific metal‐oxo‐clusters, (b) hetero‐bonded metal‐oxo‐clusters, and (c) core/shell type metal‐oxo‐cluster configuration.