Papers by Keyword: Organic-Inorganic Hybrid

Abstract: The flexibility in replacing the organic part of the organic-inorganic hybrid material has become an interesting material parameter to tune the functionality of their inorganic part. Based on the optical absorption in the UV-VIS region, we are able to observe the d-d transition of the Mn²⁺ in (C₆H₅CH₂CH₂NH₃)₂-MnCl₄, and (NH₂CH₂CH₂NH₂)₂-MnCl₄ hybrid compounds. The results of this the experiment clearly indicate that there are six transitions related to the d-d transition of the Mn²⁺ from the high spin state, ⁶S, to the excited states of ⁴G, ⁴D and ⁴P. The transition energies are fitted to the Tanabe-Sugano diagram. The different in organic part change its Racah parameters and crystal field energy. This shows that the organic part could modify the bond strength between the Mn and the Cl as well as the electronic interaction.

Abstract: Quantum dots of CdSe, CdS and ZnS QDs were prepared by chemical reaction and used to fabricate organic quantum dot hybrid junction device. QD-LEDs were fabricated using layers of ITO/TPD: PMMA/CdSe/Alq₃, ITO/TPD: PMMA/CdS/Alq₃ and ITO/TPD: PMMA/ZnS/Alq₃ devices which prepared by phase segregation method. The hybrid white light emitting devices consists, of three-layers deposited successively on the ITO glass substrate; the first layer was of N, N’-bis (3-methylphenyl)-N, N’-bis (phenyl) benzidine (TPD) polymer mixed with polymethyl methacrylate (PMMA) polymers. The second layer was QDs while the third layer was tris (8-hydroxyquinoline) aluminium (Alq₃). The results of the optical properties show that the prepared QDs were nanocrystalline with defects formation. The calculated of energy gaps from photoluminescence (PL) spectrometer were 2.38, 2.69 and 3.64 eV for CdSe, CdS and ZnS respectively. The generated white light has acceptable efficiency using confinement effect which makes the energy gap larger, so that the direction of the light sites are toward the center of white light color. The hybrid junction devices (EL devices) were characterized by room temperature PL and electroluminescence (EL). Current-voltage (I–V) characteristics indicate that the output current is good compared to the few voltages ( 8-10.3 V) used which gives acceptable results to get a generation of white light. The EL spectrum reveals a broad emission band covering the range from 350 - 700 nm. The emissions causing this white luminescence were identified depending on the chromaticity coordinates (CIE 1931). The correlated color temperature (CCT) was found to be about 6250, 5310 and 5227K respectively. Fabrication of EL-devices from semiconductors material (CdSe, CdS and ZnS QDs) with hole injection organic polymer (TPD) and electron injection from organic molecules (Alq₃) was effective in white light generation

Abstract: A facile biomimetic method was developed to enhance the interfacial interaction in organic-inorganic hybrid materials. By mimicking mussel adhesive proteins, a monolayer of polydopamine (PD) was constructed on surface of Al (OH)₃ particles through a controllable coating pathway. The modified Al (OH)₃ (PD-Al (OH)₃) was incorporated into an epoxy resin. It is found that the strong interfacial interactions brought by the polydopamine benefits the effective interfacial stress transfer, leading to greatly improved flexural properties of the organic-inorganic hybrid resin.

Abstract: A carbaryl molecularly imprinted capillary monolith was prepared by organic-inorganic hybrid approach. Methacrylic acid (MAA) as functional monomer, γ-methacryloxypropytrimethoxysilane (γ-MAPS) as crosslinker, carbaryl as template molecule, and acetonitrile/dichloromethane mixture (v/v, 1:4) were used as porogen. The molar ratio of 1:6:8 (carbaryl:MAA: γ-MAPS, for which the retention factor k was 7.57, was expected to be highest for carbaryl on the optimum capillary monolith. The condition of 20 mmol/L phosphate buffer with pH value 3.5 containing 30% acetonitrile favored the carbaryl separation from three carbamates (carbaryl, fenobucarb and metocarb) through the effective imprinted length of the column which was 15 cm. As far as the screening of carbaryl from a group of structural analogs, the MIP monolith combined with capillary electrochromatography was preferred.

Abstract: A thermo-sensitive organic-inorganic hybrid nanomicrocapsule was synthesized by miniemulsion polymerization through introducing N-isopropyl acrylamide (NIPAM) monomer to the copolymer of styrene that coat around the octane droplet and 3-trimethoxysil propyl methacrylate (MPS). The penetration and releasing behavior of cresol red in this nanomicrocapsule nearby the critical temperature was investigated with ultravioletvisible spectroscopy. The results showed that both the introduction of NIPAM monomer and the temperature affect the loading and releasing of cresol red in nanomicrocapsule and the microcapsule exhibited a certain penetration rate above the critical temperature, but the penetration was inconspicuous below the critical temperature, denoting that this nanomicrocapsule could realize on-off type of environmental thermo-sensitive controlled absorption and release.

Abstract: We attempted the photo-chemical recovery of noble metals from solutions using inorganic-organic hybrid photocatalysts based on polyoxometallates (POMs) such as PMo₁₂O₄₀^3-, SiW₁₂O₄₀^4-, and γ-SiW₁₀O₃₆^8- coupled with a cationic surfactant, dimethyldioctadecylammonium (DODA). We also used γ-SiW₁₀O₃₆-O(SiC₁₈H₃₇)₂ as a photocatalyst. The four different photocatalysts dissolved in chloroform successfully photoreduced gold ions dissolved in water in a two-phase (chloroform/water) system under UV irradiation (λ< 475 nm). The γ-SiW₁₀O₃₆/DODA photocatalyst exhibited the best activity and was able to recover gold from solution. It was suggested that one-electron reduced γ-SiW₁₀O₃₆^9- , which was formed by UV irradiation, reduced gold ions to produce large two-dimensional particles. The formation of sheet-like particles indicates that the reduction of gold ions occurred at the interface between chloroform and water.

Abstract: Polysilsesquioxane xerogels have been prepared via hydrolysis and condensation of the sole precursor N-(3-Trimethoxysilylethyl)ethylenediamine (TMSEEDA) with no acid or base catalyzed sol–gel processing. Complex siloxane matrix is formed along with abundant and covalently linked ethylenediamine (EDA). After high temperature thermal treatment over 500 °C, EDA groups are completely decomposed. The as-synthesized sample exhibits strong blue emission at room temperature (RT), which is shifted to green and red bands when encountered high temperature annealing treatment (in air), promising potential applications in opto-electronics and sensor. Moreover, the PL mechanism is also discussed in details.

Abstract: This study is concerning hybrid materials composed of the magnetite and the organic polymer such as dextran. They are useful for hyperthermia of cancer. In the preparation of this material, chemical structure or molecular weight of the added polymer is expected to affect ionic interaction between polymer and iron salts, and consequently the grain size and morphology of the prepared magnetite core. Therefore, we have synthesized magnetite-polymer hybrids using various polymers. Various polymers were dissolved in iron (II) chloride aqueous solution, and then NaOH aqueous solution was added to this mixed solution. As a result, in the case of neutral and cationic polymer crystalline magnetite was precipitated in the hybrid. On the other hand, in the case of anionic polyacrylic acid, lepidocrocite was precipitated rather than magnetite. It is known that the magnetite formation progresses through intermediate Fe (OH)₂ formation and oxidation of the Fe (OH)₂ by dissolved O₂. Therefore it is considered that tight ionic interaction is constructed between the iron ions and the carboxyl group in the polyacrylic acid to form a complex, and the Fe (OH)₂ formation is inhibited. When the hybrid was prepared by addition of NaOH aqueous solution to iron (II) chloride solution, and subsequent addition of the different polymers, magnetite formation was not inhibited irrespective of kind of polymer. The present results indicate that crystalline structure of the magnetite phase in magnetite-polymer hybrid is strongly affected by the chemical structure of polymer additives or the order of addition.

Abstract: Chemically synthesized collagen with triple helix structure similar to natural collagen has been developed as a safe biomaterial. If the chemically synthesized collagen is deposited with apatite, they are expected for novel bone substitutes having bioactivity and bioresorbability. Although apatite formation on the chemically synthesized collagen has been examined, highly supersaturated condition such as 1.5SBF with ion concentration 1.5 times those of simulated body fluid (SBF) is needed to achieve apatite formation. In the present study, we intended acceleration on the apatite formation on the chemically synthesized collagen by immobilization with polyglutamic acid (PGA). PGA is known as biodegradable and biocompatible polypeptide having excellent apatite-forming ability. We examined effects of the immobilization procedure on mineralization behavior in SBF. At first, PGA was immobilized on porous sponges of chemically synthesized collagen in aqueous solutions containing PGA and CaCl₂. As a result, not only apatite but also calcite-type CaCO₃ was deposited on the specimens in SBF. The calcite formation was occurred during the treatment with PGA solution. pH of the solution was adjusted to 7 by NaOH solution in order to avoid dissolution of the collagen. During this procedure, Ca (OH)₂ would be precipitated by locally increase in pH of the solution and converted into the calcite. When the PGA solution treatment was shortened so as to prevent the calcite formation, single phase of the apatite was formed in SBF. The present results indicate that crystalline phase deposited on the chemically synthesized collagen can be controlled by fabrication procedure, and provide fundamental design of composites containing apatite and chemically synthesized collagen useful for bone regeneration.

Abstract: Aluminum sheet was encapsulated by inorganic-organic hybrid film through a base catalyzed sol-gel method using organic acrylate silane resin PMBV and TEOS as precursors. FTIR and AFM characterizations prove that PMBV and TEOS have hydrolyzed and co-condensed with each other in the sol-gel process to form an uniform film on the surface of aluminum sheet. XPS result shows hydroxyl groups on aluminum surface have taken part in the co-condensation reaction.