Monodisperse non-aggregated nanoparticles of titania are obtained through hydrolysis at 60°C of titanium butoxide in the presence of acetylacetone and para-toluene sulfonic acid. After drying the resulting xerosols can be dispersed without aggregation in water-alcoholic or alcoholic solutions. The characterizations of the nanoparticles have been carried out by using quasi-elastic light scattering (QELS), 13C 1H in solution and X-ray diffraction, TEM, TG-DTA, 13C CP-MAS NMR in the solid state. The mean size of the anatase oxide core can be adjusted in the I to 5 nanometer range by a careful tuning of the synthetic conditions. The anatase particles are surrounded by acetylacetonato ligands, para-toluene sulfonate based species and water.

New hybrid materials made of polydimethylsiloxane species (chains and cyclic species) crosslinked at the molecular level by O=V(O-)3 units with a very high degree of homogeneity and dispersion even for a V/Si ratio of 10% have been synthesized and characterized mainly by 29Si, 51V MAS NMR, DSC and DMA. The structure of these hybrids is very different from those proposed for the other dimethylsiloxane-transition metal oxide systems. These dimethylsiloxanevanadates copolymers exhibit higher glass transition temperatures than usual PDMS and a very sharp variation of the loss factor tanδ. These hybrid materials exhibit at low temperature a strong phosphorescence usually associated to a Ligand to Metal Charge Transfrer process.

Transition metal oxide / phenylphosphonate hybrids with M/P ratios ranging from 1 to 5, (M= Ti, Zr) and metal phosphonates (M/P = 0.5) have been prepared by a sol-gel process involving in a first step the non-hydrolytic condensation between metal alkoxide and phosphonic acid leading to M-O-P bonds, followed by the hydrolysis-condensation of the remaining M-OR groups. The composition, texture and structure of the materials were investigated using EDX, TGA, XRD, IR and 31P NMR.

The preparation of liquid, methoxylated, polysiloxane hybrid resins containing Me2Si(O-)2 (D) or MeHSi(O-)2 (DH) units cross-linked by Si(O-)4 (Q) units was attempted using the nonhydrolytic condensation reaction between Si-Cl and Si-OMe groups, catalyzed by ZrCI4. The structure of the resins was investigated by 29Si NMR, which showed that redistribution reactions played a prominent role. Thus, Si-OMe/Si-OSi redistributions lead to a highly homogeneous, random structure for the D/Q resin. On the other hand, this route does not apply to the synthesis of DH/Q resins, due to the redistribution of Si-H bonds which leads to the escape of MeSiH3 and to the formation of T and TH units.

The increasing interest in inorganic-organic nanocomposites which offer the possibility to build up both an inorganic and organic network by hydrolysis and condensation and by polymerization reactions, respectively, leads to the development of a new class of double bond functionalized silanes. These 2-vinylcyclopropyl silanes were synthesized e.g. by reaction of 1-methoxycarbonyl-2-vinylcyclopropane-l-carboxylic acid with 3-isocyanatopropyltriethoxysilane. Hydrolysis and condensation of the alkoxy groups as well as cocondensation with tetraalkoxysilanes lead to solvent-free liquid resins that can be cured by UV-light-induced radical polymerization of the vinylcyclopropane group. The synthesis and characterization of different 2-vinylcyclopropyl silanes, hydrolysation and condensation behavior and first results of the radical polymerization will be discussed.

Organically-modified silicates have been synthesized from RSi(OEt)3 (R = CH3, C2H5, C8H17, CH2=CH, C6H5) and TEOS under acidic conditions, in the presence of cethyltrimethylammonium (CTAB). The introduction of RSiO1.5 units with R/Si =0.2, affects the ordering of the expected hexagonal silicate phase, except when R = C6H5. The sample containing phenyl functions was thus submitted to surfactant extraction; calcination at 350°C appears to be more efficient, and less disruptive for the network ordering than a washing procedure in ethanol. Nitrogen adsorption measurements on the hexagonally ordered calcined sample that still contains phenyl groups, yields a type I isotherm, typical of a microporous solid. BET method leads to a surface area of 1000 m2/g and a pore volume of 0.32 cm3/g.

The influence of polymethylmetacrylate on the rheological and structural characteristics of zirconia sols was analyzed by shear stress versus shear rate measurements, quasi elastic light scattering and infrared spectra. The thickness of coated film determined by profilometry increases linearly with the relative volume of PMMA. The addition of PMMA led to the polycondensation reaction and the formation and growth of zirconia particles.

Organo-inorganic hybrid nancomposites derived from poly(ethylene oxide) and montmorillonite silicate are prepared by an alternative procedure to classical polymer intercalation either from solutions or by polymer melt-intercalation. XRD, FTIR, DSC, elemental microanalysis and SEM techniques are applied for structural characterization of the resulting materials. The electrical properties of these nanocomposites are studied by means of the electrical impedance spectroscopy (EIS) showing enhanced ionic conductivity compared to similar samples prepared by intercalation from solution.

We have taken a unique approach to the synthesis and study of hybrid organic/inorganic materials. Our method involves synthesizing nano-size inorganic P1R7Si8O12 clusters which contain seven inert “R” groups for solubility and only one functional “P” group for polymerization. This strategy permits the synthesis of melt processable, linear hybrid polymers containing pendent inorganic clusters and allows us to study the effect these clusters have on chain motions and polymer properties. The synthesis of norbomenyl-based polyhedral oligomeric silsesquioxane (POSS) macromers, their ring opening metathesis copolymerizations with varying amounts of norbornene, and analysis of the effect of the pendent POSS group is presented. The mechanical relaxation behavior and microstructure of norbornyl-POSS hybrid copolymers have been examined for their dependencies on the mole fraction of POSS-norbornyl monomer, as well as for potential sensitivity to the seven inert “R” groups present in each POSS macromer. POSS copolymerization is observed to enhance the α-relaxation temperature, Tα, in proportion to the mole fraction of POSS-norbornyl comonomer. Interestingly, however, the magnitude of this dependence is larger for POSS-norbornyl comonomer possessing cyclohexyl groups (CyPOSS) than for cyclopentyl groups (CpPOSS). While POSS copolymerization yields only slight enhancement of the tensile storage modulus measured near room temperature, at temperatures lower than a strong mechanical relaxation (β-relaxation near T = -75 °C), there is a significant POSS-reinforcement of the storage modulus.

Sol-gel derived organic-inorganic hybrid materials with potential fields of application as refractive optical components for example laser diode bars and ophthalmic lenses are presented. The main components of the hybrid materials under investigation are precondensed methacryloxypropyltrimethoxysilane (MPTS, denoted: M) with an organically polymerisable methacrylic functionality and tetraethyleneglycoldimethacrylate (TEGDMA, denoted: T) as crosslinking organic monomer with two polymerisable double bonds. The molar ratios of the components ranged from M/T 10/90 up to M/T 70/30. The polymer derived from pure TEGDMA (M/T 0/100) served as a reference material. In addition to this nanoscaled TiO2 particles (5 wt.% and 10 wt.%) were incorporated in the organic-inorganic M/T 30/70 matrix to increase the refractive index of the resulting nanocomposites. For the preparation of the different systems, precondensed MPTS was mixed with TEGDMA, the nanoparticulate titania sol (when used), an appropriate photoinitiator and a thermoinitiator. The reaction mixtures were polymerised photochemically and/or thermally. The propagation of the free radical polymerisation reaction after photopolymerisation and subsequent thermal curing was followed by IR-spectroscopy, showing that the degree of double bond conversion is strongly increased by the thermal curing step. Incorporation of increasing amounts of TiO2 nanoparticles resulted in reduction of the double bond conversion compared to the corresponding unfilled system. The homogeneous dispersion of the titania particles in the completely cured M/T 30/70 matrix could be manifested by high resolution transmission electron microscopy (HTEM). The thermomechanical properties of the completely cured nanocomposites were monitored by dynamic mechanical thermal analysis (DMTA) showing a strong dependence on composition.

We have synthesized several metal xanthate complexes from metal salts and xanthate potassium salts. Powders of several of the materials were sorted and tested for their nonlinear optical properties. Cadmium xanthate demonstrated phase matchability for frequency doubling of 1.06 micron light and generated a very strong second harmonic signal.

Reaction of Ti(OR)4 or Zr(OR)4 with carboxylic acids resulted in the formation of crystalline carboxylate-substituted oxotitanium and oxozirconium clusters with different Ti/Zr : carboxylate ratios. Structural investigations showed that the cluster cores are rutile- or zirconia-like if the carboxylate : metal ratio does not exceed 1.33 (for Ti) or 2 (for Zr), respectively. When the carboxylate : metal ratio is increased beyond these values, more open clusters and eventually polymeric structures are obtained.

We have examined the effect of organic solvent on the microstructures of hydroxyapatite (HAp) formed by hydrolysis of α -tricalcium phosphate ( α -TCP) in heterogeneous solvent system (water-hydrophobic organic solvent). The shape of HAp was like ultrafine whisker (length : about 1 ∼- 4 µ m) and its size depended on the used organic solvent.

As a simple hybridization, incorporation of fluoride anion (F−) into HAp was attempted in similar system to obtain fluoridated apatite [Ca10(PO4)6(OH)2−x Fx.]. The formation rate was strongly affected by the concentration of F− and reaction temperature. Although the product in water (in the absence of organic solvent) consists of fine particles less than 1 µ m, the product prepared in the heterogeneous solvent system was mixture of ultrafine particles ( ∼ 0.1 µ m) and needle-like particles (length : about 1 ∼ 4 µ m, width : ∼ 0.5 µ m). The microstructures of HAp and FHAp were controlled by hydrophobicity of organic solvent.