Recently, LDH have been considered as a new kind of gene delivery system [1, 2]. In this work, we report the formation of magnesium-gallium LDH-DNA nanohybrids using the coprecipitation method. This “self assembly” approach enabled the incorporation of long DNA fragments up to 6000–8000 bp. X-ray diffraction analyses indicate a parallel orientation of DNA double helix in the interlamellar space with respect to the hydroxide sheets. The Mg/Ga molar ratio within the hydroxide layers appears to be determined by DNA macromolecules which may interact with charged complexes that form during cation hydrolysis. The presence of DNA macromolecules also inhibits the crystal growth: hydrodynamic diameter measurements revealed homogeneous populations of particles with a mean diameter ranging from 90 to 150 nm, compatible with cell penetration through endocytosis. Concerning the charge surface of this new DNA delivery system, ζ-potential measurements indicate negative values ranging from –20 to - 40 mV which suggest incomplete DNA intercalation. Yet, this small negative surface might be suitable for protecting DNA from extra-cellular degradations without preventing cell penetration.

Colloidal particles with a controlled morphology combining both organic and inorganic parts were synthesized through a seeded emulsion polymerization process. Silica seed particles (from 50 to 150 nm in diameter) were first surface-modified by the adsorption of an oxyethylene-based macromonomer. Then, emulsion polymerization of styrene was carried out in presence of these particles, the formation of polystyrene nodules being highly favored at the silica surface in such conditions. The ratio between the number of silica seeds and the number of growing polystyrene nodules appeared to be one of the key parameters to control the morphology of the final hybrid nanoparticles. When this ratio is close to 1, original hybrid dumbbell-like nanoparticles were mainly obtained.

Organic-Inorganic hybrid gels with hierarchical well-defined macropores and supramolecularly templated mesopores with long-range orders have been synthesized in the systems of bridged poly(silsesquioxane) systems. Nonionic surfactants such as poly(ethyleneglycol)-poly(propyleneglycol)- poly(ethyleneglycol) triblock copolymers, EOPOEOs, were found to be effective both in inducing the phase separation to give macroporous morphology and in templating the mesopores with narrow size distribution. The number of methylene units in the bridge, changed from 1 to 6 in the present experiments, affected both the phase separation tendency and template strength. In the system containing 1, 2-bis(trimethoxysilyl)ethane, 2D-hexagonal arrangement of mesopores have been prepared in the gel skeleton comprising the well-defined continuous macroporous network with an aid of micelle-stabilizing agent.

Gold-dendrimer nanocomposite materials have various applications in catalysis, optics, biological sensing, cancer therapeutics, as well as building blocks to assemble functional films. Primary amine-terminated poly(amidoamine) (PAMAM) dendrimers of different generations (generation 2 through 6) were used as templates to synthesize gold-dendrimer hybrid nanocomposites. UV-Vis spectrometry, fluorescence, transmission electron microscope (TEM), zeta-potential, and polyacrylamide gel electrophoresis (PAGE) were used to extensively characterize these nanocomposite materials. Results indicate that the structure of gold-dendrimer nanocomposites changes as the function of generation and their size decreases with the increase of the generation number of dendrimer templates. TEM shows that aggregated gold-dendrimer nanocomposites are polycrystalline. These nanocomposites are fluorescent and display a stronger emission intensity (458 nm) than commercially available gold nanoparticles of similar size do. PAGE analysis shows that the gold-dendrimer nanocomposites have electrophoretic migration patterns that are similar to those of the corresponding dendrimer templates. The combination of applied different analytical techniques provides new insights into the structure and properties of gold-dendrimer nanocomposite materials.

Attractive sol-gel derived di-urethane cross-linked poly(oxyethylene), POE/siloxane hybrids (di-urethanesils) doped with europium triflate, Eu(CF3SO3)3 were examined by Fourier Transform mid-infrared (FT-IR), Raman (FT-Raman) and Photoluminescence spectroscopies with the main goal of elucidating the chemical environment of the cations in these materials. In these hybrids the POE chains contain about 13 oxyethylene repeat units. Samples with compositions ∞ > n ≥ 5 (where n indicates the ratio of (OCH2CH2) moieties per Eu3+ion) were investigated. The FT-IR and FT-Raman data obtained provided unequivocal evidence that the ether oxygen atoms of the polymer chains start to interact with the Eu3+ ions at n = 20. The presence of a crystalline POE/Eu(CF3SO3)3 complex was detected at n ≥ 20. Photoluminescence results demonstrated that the doped di-urethanesils studied here are room temperature (RT) efficient full-color emitters. Two distinct cation local sites were unequivocally identified at n = 200 and 20. These Eu3+ local coordination sites involve the oxygen atoms of the urethane carbonyl groups and weakly coordinated Eu3+/CF3SO3 ionic species. For the most concentrated hybrid (n=5) evidences of a third local-environment probably involving the oxygen atoms of the polymer chains was observed.

Inorganic/organic hybrid material of CdSe/ZnS core/shell nanocrystals (NCs) covered with organic ligands was prepared with ligand exchange reaction in order to facilitate carrier injection into NCs through the organic ligands. The organic ligands used in this study, 2-naphtalenethiol and bathophenanthroline, were selected as model compounds according to adjustment of highest occupied molecular orbital and lowest unoccupied molecular orbital of the ligand to valence band maximum and conduction band minimum of the CdSe NCs, respectively. The prepared hybrid NCs easily disperse in polar organic solvents such as CHCl3 and show photoluminescence only from the CdSe/ZnS core/shell NCs. Current-voltage characteristics of the ligand exchanged NCs thin films sandwiched between electrodes were investigated. It was shown that conductivity of the film was improved by the introduction of carrier injecting ligands in comparison to the ligand unexchanged trioctylphosphine oxide-capped CdSe/ZnS NC thin film.

Monolithic pure silica gels with hierarchical macro-mesoporous structure have been synthesized via spontaneous sol-gel process from silicon alkoxide using a structure-directing agent and a micelle-swelling agent. Monolithic body with well-defined co-continuous macropores is a result of concurrent phase separation and sol-gel transition induced by the polymerization reaction, whereas the mesopores are templated by the cooperative self-assembly of inorganic species, a structure-directing agent and a micelle-swelling agent. The following removal of surfactants by heat-treatment gives silica gels with hierarchical and fully accessible pores in discrete size ranges of micrometers and nanometers. The highly ordered 2D-hexagonal arrays of mesopores have been confirmed by X-ray diffraction measurements and FE-SEM observations. Furthermore, by further additions of the micelle-swelling agent, the mesostructural transition from well-ordered 2D-hexagonal arrays to mesostructured cellular foams (MCF) have been induced accompanied by minor modifications of the micrometer-range structure.

The present paper describes the mineralization of calcium carbonate at a low temperature (4 °C) and in presence of additives. Aspartic acid immobilized polyacrylic acid (PA-Asp) induced the nucleation of spherical vaterite polymorph at 4 °C. But at room temperature, a thin film of calcite was deposited. Moreover, stable amorphous calcium carbonate was precipitated in presence of magnesium at low temperature. The observed results show that low temperature and presence of additives influence the nucleation, polymorph selectivity and morphology of the precipitated calcium carbonate.

Bidentate ligands are potentially useful to modify metal alkoxides precursors for sol-gel processing. However, anionic bidentate ligands are needed to get a strong coordination, while diamines as neutral bidentate ligand form coordination polymers [Ti2(OR)8(diamine)2]∞ when reacted with Ti(OR)4. The Lewis acidity of metal alkoxides may cause organic side reactions. The first is the formation of ester and water in the reaction with carboxylic acids, and therefore carboxylate-substituted metal oxide clusters of the general composition MnOx(OH/OR)y(OOCR)z are obtained instead of substituted monomeric precursors. The second side reaction discussed is the cleavage of β-diketones by metal alkoxides. Despite this side reaction, 3-acetyl-6-trimethoxy-silyl-hexane-2-one is a useful compound to prepare single-source precursos for silica/metal oxide composites.

Magnetite (Fe3O4) nanoparticles were synthesized by chemical coprecipitation and were characterized using TEM, XRD, and VSM. XRD and TEM measurements indicate that the average particle size was approximately 10 nm. The nanoparticles were coated with polypyrrole using oxidative polymerization. TGA results show that the polypyrrole coating is 28.5wt%. TEM images indicate that the nanoparticles are bound in clusters by polypyrrole. Measurements show that nanoparticles may hinder curing of the polymer matrix, but they can be effective in producing composites with higher modulus and magnetic permeability at lower frequencies.

The “old” 1H→29Si CP MAS (Cross Polarization Magic Angle Spinning) experiment is revisited in the frame of silica hybrid gels and silsesquioxanes. It is proved that the analysis of the CP curves can lead to erroneous interpretation in terms of quantification. We show that this results from false assumptions concerning the dynamical CP parameters THSi (cross relaxation time constant) and T1ρH (1H relaxation time in the rotating frame). In other words, at least one parameter must be measured independently, in order to constrain the fits of the CP curves. Moreover, we demonstrate that the well-known (and universally used…) “spin bath” assumption is not always valid in the frame of 1H→29Si CP MAS NMR. This point is clearly demonstrated on model silsesquioxanes exhibiting short Si-H bonds. In this case, the transfer of magnetization (called coherent transfer) presents clearly oscillations, which can lead to the precise measurement of Si-H distances by solid state NMR! Curiously, the coherent transfer of magnetization is also demonstrated for weakly coupled spin systems, encountered in the silsesquioxane (SiO1.5CH3)8 or T units gels. In this case, a numerical simulation of the CP curves gives a deep insight in the chemical environment of the 29Si sites in terms of Si-H distances and local molecular reorientations. For weakly coupled systems, 1H-1H spin diffusion must be suppressed, in order to reveal the coherent character of the transfer: the quenching of spin diffusion is demonstrated by using a modified version of the CP MAS experiment. We introduce here the Lee-Goldburg CP MAS experiment (CPLG MAS) for that purpose. The “off resonance” 1H irradiation (at the magic angle) ensures the strong suppression of the 1H-1H homonuclear dipolar interaction and therefore the efficient quenching of spin diffusion during the CP transfer.

Interleaved monomers and polymers between the sheets of layered double hydroxide (LDH) (hydrotalcite-type) materials are considered as carbonaceous source. After a charring process constituted of a carbonisation and a subsequent demineralisation, carbonaceous materials of interesting textural properties were obtained. The initial preparation of the polymer LDH hybrid phase was found to strongly orientate the textural characteristics, microporous volume and creation of mesoporosity. Several methods to assess the microporosity, t-plot, αs and Dubinin-Astakhov, are compared. Specific surface area as high as 2300 m2/g measured by BET method and microporous volume of 1.07 mL/g were obtained. The carbonaceous materials tested as supercapacitor in acidic medium present capacitances in the range 60 - 120 F/g associated to a good behavior in cycling.

We have prepared organic-inorganic hybrid materials (OIHM), incorporating an organic phase in the inorganic precursor sol, using high power ultrasound for assistance with agitation. A sono-ormosil results after gelation. Colloidal silica particles have been added to these hybrids to enable network porous volume and pore radius to be tailored to specific requirements. Finally, in vitro bioactivity of this material has been promoted by adding calcium to the initial sol. The structure and bioactivity of these materials have been subjected to preliminary study, including their mechanical behaviour. These materials have a very fine structure especially after colloidal silica particles have been included. When immersed in a solution simulating blood plasma, they are bioactive, and the sample with colloid particles presents a better behaviour in vitro

Materials based on alkynyl platinum derivatives and thiacalixarenes were prepared through the sol-gel process The molecular species were grafted to the matrix (class II hybrid) in order to maximise the concentration and the stability of the final solid-state material Broadband optical limiting performance in the visible wavelength region was observed in the prepared materials Thermomechanical characterisation of the matrix is also discussed.

Synthesis of hybrid aerogel materials that contain both selectively reactive nanoparticles and nanoparticles with appreciable magnetic susceptibilities will be reported. This has been achieved by a two stages process. First silica-bioderived polymer hybrid aerogels with incorporated metal ions were synthesized and then reduced by photolytically induced chemical reductions or decompositions. For example, silica-chitosan hybrid gels were prepared, Au(III) ions were coordinated to the chitosan, and, after forming the Au(III)-silica-chitosan aerogel by SCL extraction, UV photolysis afforded gold nanoparticles of controlled size in the aerogel. Second, an iron-containing organometallic compound, such as iron carbonyl itself, was absorbed into the aerogel, and then heating or photolysis afforded reduced metal decomposition products. Ferromagnetic organic/inorganic hybrid products containing Au(0) nanoparticles were obtained. Their size (TEM), crystallographic, optical and magnetic properties are discussed. Reactions of thiol compound with the metal nanoparticles in the aerogels were studied.

The aminopropylsiloxane-based organic/inorganic hybrid is known as a sensitive material toward NO2 gas for optical sensing systems but it has the irreversible detection. The affinity of the aminopropylsiloxane-based organic/inorganic hybrid toward NO2 gas was controlled by incorporating an Nb inorganic component derived from Nb(OC2H5)5 into the hybrid structure. The amino groups had a strong coordination bond with hydrolyzed Nb(OC2H5)5 and/or an acid-base pair with an oxoanion formed by hydrolysis of Nb(OC2H5)5. Thus, the strong solid-basicity of the aminopropylsiloxane-based organic/inorganic hybrid was weakened. The aminopropylsiloxane-based organic/inorganic hybrid containing an Nb inorganic component provided reversible sensing toward NO2 gas in an optical sensing system. NO2 is thought to be more weakly adsorbed because of the weakened basicity of the amino groups.

Using sol-gel technology combined with water-in-oil (W/O) emulsions, we have developed an innovative method for producing ceramic particles with independent control over the release rate and particle size. The average particle size can be varied from 10 nm to 100 μm and is controlled by the emulsion chemistry. The release rate can be independently varied from mg/hours to mg/month, and is controlled by the internal microstructure of the particles and the initial sol-gel chemistry.

It is difficult to deposit a very thin polymer layer onto a fiber-shaped substrate from solution because the high interfacial energy can lead to dewetting. This difficulty presents itself when attempting to apply a gate dielectric to conductive fiber substrates during the fabrication of fiber transistors for use in applications such as “electrotextiles” and optical switches. We present a dip coating process that applies a gate dielectric to metal-coated optical fibers with high uniformity and reproducibility, resulting in pentacene field-effect transistors (FETs) with excellent transistor characteristics including mobilities up to 0.4 cm2/Vs and on/off ratios up to 7000. In one case, a memory effect was demonstrated. Several gate dielectrics were successfully applied to the optical fibers, suggesting a baseline set of suitable materials for this purpose. A thorough study of the dip coating conditions is presented, including proposed explanations of the effects of different coating procedures and solution physical properties.

In situ investigations have proven to be a very useful means of understanding the different processes involved in the formation of mesoporous materials. In this communication, we demonstrate the potential of in situ small angle x-ray scattering, SAXS and x-ray diffraction, XRD, measurements for giving both qualitative and quantitative results on the structural evolution during the early stages of the surfactant-silicate composite formation. The examples given are based on results obtained for 2D hexagonal structures, synthesized both under acidic and alkaline conditions. Careful analysis of both the scattering and diffraction patterns allows the different stages of the formation to be described in some detail. Thus, new synthesis approaches can be foreseen that allow the structure of the final hybrid mesophase to be rationally controlled.

Multi-cpoxy functional - glycidyl ether is used as a cross-linking epoxy compound between modified 22'44'-tetrahydroxybenzophenone and silicone molecules. The adduct reaction products, as effective abrasion resistant coatings and yet reactive in the sol gel process, are formulated into the colloidal based polysiloxane resin as an essential part of the solution for dip coating sheets. Such coatings incorporate ultraviolet radiation selection or absorbing compounds with superb chemical stability and mechanical strength for coatings on substrates such as glass. The hardness of these coatings was measured at 6H following ASTM (D-3363) film hardness by pencil test. The resulting coatings were exposed to ultraviolet (UV-A) radiation during a time greater than 600 hours. The exposed samples still maintain excellent absorption in the UV range.