Papers by Keyword: Organic-Inorganic Hybrid

Abstract: For the purpose of bioinert coating on electronic devices, we developed the non-hydrolytic sol-gel derived organic-inorganic hybrid materials by addition of epoxy groups which can adhere strongly to the surface of electronic silicon device. The adhesion and chemical properties of hybrids were investigated as a function of epoxy group contents. The hybrids were prepared from 3-metacrloxypropyltrimethoxysilane (MPTS) and 3-glycidoxypropyltrimethoxysilane (GPTS) and diphenylsilanediol. The transparent hybrids were obtained after curing by UV irradiation. The adhesion properties of the hybrids were estimated by the maximum load to resist in a scratch test. The adhesion property of the hybrids increased with addition of GPTS and the highest adhesion was obtained from the hybrid with 5-10 mol% of GPTS. From the element analysis, Si concentrations of all the solutions were less than 2 mM after soaking for 7 d. The Si concentrations were not changed with increasing soaking period. The addition of epoxy groups is effective on improvement of adhesion property of the silica-based hybrid without loosening its chemical stability.

Abstract: Chitosan-GPTMS (γ-Glycidoxypropyltrimethoxysilane) hybrid hydrogels were synthesized with β-glycerophosphate (β-GP) as the additive agent. Chitosan-GPTMS sols were fluid at room temperature and transformed to hydrogel at 36.5°C in several min. The gelation time of the hydrogels was shortened by the addition of GPTMS. From NMR experiments, this gelation behavior depended on some factors, namely, electrostatic interaction between the phosphate groups of β-GP and the amino groups of chitosan chains, crosslinking between the epoxy groups of GPTMS and the amino groups of chitosan, and polycondensation of the methoxy groups of GPTMS. The Si(IV) released from the hydrogels promoted the cell adhesion and ALP activity of osteoblastic cells MG63.

Abstract: Apatite-polymer hybrid has attractive features as novel bone substitutes such as both ability of bone-bonding and mechanical performances analogous to those of natural bone, i.e. high strength and high flexibility. As a method for development of such hybrids, biomimetic process has been proposed, where apatite formation is induced on the surfaces of organic substrates at ambient conditions in simulated body fluid (SBF) with ion concentrations similar to those of human extracellular fluid, or related solutions supersaturated with respect to the apatite. In this process, heterogeneous nucleation of apatite is triggered by specific functional groups. This apatite nucleation is enhanced by release of calcium ions (Ca2+) from the materials which increases degree of supersaturation of surrounding fluid with respect to apatite. In the present study, we attempted to prepare apatite-polyamide hybrids by biomimetic process. Polysaccharides and natural polypeptides containing carboxyl group (-COOH) were used as a starting material, and apatite formation ability was compared. It was found that the apatite formation was governed by not only content of the carboxyl group but also ionic interaction with Ca2+.

Abstract: A hierarchical meso-/macroporous titanium phosphonate (TPPH) hybrid material was prepared via a simple surfactant-assisted process with the use of the precursor tetrabutyl titanate and 1-hydroxy ethylidene-1,1-diphosphonic acid. The prepared hybrid TPPH presented amorphous phase, exhibiting a hierarchical macroporous structure composed of mesopores with a pore size of 2.0 nm. The BET surface area is 256 m2/g. The hydroxyethylidene-bridged organophosphonate groups were homogeneously incorporated in the network of the hierarchical porous solid, as revealed by FT-IR, MAS NMR, XPS, and TGA measurements. The optical properties and photocatalytic activity of the hierarchical TPPH material were investigated in comparison with those of hierarchical porous titanium phosphate and pure mesoporous titania materials, showing superiority of the inorganic-organic hybrid framework, suggesting promising photocatalysts for wastewater cleanup.

Abstract: A series of hybrids (CnH2n+1NH3)2MCl4 with quantum-well energy-band structure were synthesized by chemical reaction in HCl solutions, in which M(Co,Ni,Cu,Zn) and n(2,4,6,8,10,12) varied to adjust the quantum-well depth and the barrier width, respectively. The X-ray diffraction patterns and scanning electron microscopy images of the products demonstrate that they crystallize well with the typical layered structures. However, the analogues of Ni can not be successfully synthesized in the same way. Concerning the energy-band structure, the colors of the products reveal that the quantum-well depth is more important than the barrier width for controlling the properties of the hybrids.

Abstract: Sol–gel synthesis is used for the fabrication of new materials with technological applications including ceramics for implants manufacturing, usually termed bioceramics. Many bioactive and resorbable bioceramics, that is, calcium phosphates, glasses and glass–ceramics, have been improved by using the sol–gel synthesis. In addition, the soft thermal conditions of sol–gel methods made possible to synthesize more reactive materials than those synthesized by traditional methods. Moreover, new families of bioactive materials such as organic–inorganic hybrids and inorganic compounds with ordered mesostructure can be produced. In hybrid materials, the inorganic component ensures the bioactive response whereas the organic polymeric component allows modulating other properties of the resulting biomaterial such as mechanical properties, degradation, etc. On the other hand, the sol–gel processes also allow the synthesis of silica ordered mesoporous materials, which are bioactive and exhibit – as an added value – a possible application as matrices for the controlled release of biologically active molecules (drugs, peptides, hormones, etc.). Finally, by combining the bioactive glasses composition with synthesis strategies of mesoporous materials, template glasses with ordered mesoporosity can be obtained. In this chapter, the advances that sol–gel technology has brought to the silica-based bioactive bioceramics are presented.

Abstract: To control the microstructure and the responsive rates of hydrogels, a temperature-induced phase separation (TIPS) method applied to an organic-inorganic hybrid hydrogel. A copolymer between thermosensitive poly(N-isopropylacrylamide), polyNIPA, and a vinyl monomer possessing a trimethoxysilyl group was synthesized by radical reaction. Its cross-linking could be carried out by hydrolytic polycondensation of trimethoxysilyl groups. During both reactions, the pre-gel solution was separated into two phases by heating above a lower critical solution temperature of the elongating polyNIPA copolymer. The responsive rates of the microporous gel could be controlled by characteristic diffusion path length as the thickness of micropore wall, instead of the macroscopic sample size. Therefore, the shrinking rates of the hydrogel could be successfully maximized by fixing the phase-separated, microporous polymer network. Besides the interconnectivity of generated pores, the thermally triggered shrinking kinetics was investigated.

Abstract: To control and maximize the shrinking rates of thermo-sensitive organic-inorganic (O-I) hybrid gels, microporous structure of gels could be controlled by ice-templating. Water-swollen gels easily became porous after freezing. Applying the freezing method effectively accelerate the shrinking rates of the poly(N-isopropylacrylamide), polyNIPA-based O-I hybrid gels by two different ways. One is the interpenetrating network with polyNIPA and polysiloxane. The other is the copolymer network of NIPA and a vinyl monomer possessing the trimethoxysilane, of which crosslinking was carried out by sol-gel reaction. Their thermally-triggered shrinking kinetics was investigated by measuring the weight change of gels. Shrinking coefficients (D) were determined by fitting the shrinking data with the Fick’s model. The coefficients after applying the freezing method increased to approximately 10-3 cm2s-1 while those before freezing were on the order of 10-5 - 10-6 cm2s-1.

Abstract: The organic/MoO3 hybrid sensors show a distinct response to aldehyde gases, formaldehyde and acetaldehyde, by changing the electrical resistance, whereas they show almost no response to other VOCs. The organic/MoO3 hybrids have a potential for selective VOC detection because the sensing properties of organic/MoO3 hybrids can be controlled by the kind of interlayer organic components. In this study, we have carried out the detail characterization of the interlayer of the organic/MoO3 hybrids as well as the valence of Mo and evaluation of their sensing properties.

Abstract: Titania/organically modified silane hybrid thin films for photonic applications were prepared by combining a low temperature sol-gel technique and a spin-coating process from an organic-inorganic hybrid system. Effects of the titanium content and heat treatment temperature on the structural and optical properties of the hybrid thin films were characterized by atomic force microscopy and UV-visible spectroscopy. It is found that the optical and microstructural properties of the hybrid thin films depend on the heat-treatment temperature and titanium molar contents. The thickness and the refractive index of the hybrid thin films were also measured and found to be related to the heat treatment temperature and titanium molar content. These results indicate that a dense and high transparent hybrid thin film can be obtained at a low heat treatment temperature. Potential photonic device structural patterns can easily fabricated from the as-prepared hybrid thin films by using etching process.