The organotin oxo-carboxylate cluster {BuSnO(O2CC6H4-4-NH2)}6 (1), which exhibits a hexagonal prismatic oxo-core, was synthesized from BuSnO (OH) and p-aminobenzoic acid. Its peripheral functionalization with triethoxysilyl moieties was achieved through the reaction with 3-isocyanatopropyltriethoxysilane (ICPTES) which preserves the oxo-carboxylate framework and yields {BuSnO[O2CC6H4-4-NHC (O)NH (CH2)3Si (OEt)3]}6 (2). Both compounds were characterized by multinuclear NMR (119Sn, 1H, 13C, 29Si).

Hydrolysis and condensation of trialkoxysilanes, HSi(OMe)3 and HSi(OEt)3, has been used to prepare polyhydridosilsesquioxaes for dielectric applications. In this study we examined the ability of trimethoxysilane (TMS) and triethoxysilane (TES) to undergo sol-gel polymerization to afford gels. Sol-gel polymerization experiments were conducted under acidic (HCl), basic (NaOH), and neutral conditions in methanol or ethanol. Gels prepared with basic catalysts were exothermic with the evolution of hydrogen gas. Gel times are compared with silica gels prepared from tetramethoxysilane (TMOS) and tetraethoxysilane (TEOS). Gels were worked up under aqueous conditions to afford xerogels. Surface area analyses by nitrogen sorption porosimetery revealed that the materials were mostly mesoporous materials with surface areas in the hundreds of square meters per gram. Solid state 29Si CP MAS NMR was used to determine the amount of hydrido group remaining in the xerogels. Gels prepared under acidic conditions were essentially polysilsesquioxanes with very little loss of hydride functionalities. In gels prepared under basic conditions the hydride groups were completely gone leaving silica gels. Gels prepared with neutral water lost approximately 66% of the hydride groups.

Clay-polymer nanoparticulate composite materials are evaluated by the X-ray diffraction technique. The basal plane spacing provided information about the degree of intercalation and exfoliation of the 2: 1 layered clay structure. Both intercalation and exfoliation are controlled by the identity of the polymer and the clay:polymer ratio.

Hybrid magnetic composites made up of calibrated maghemite nanoparticles well dispersed in an epoxide resin were obtained by polymerization of the resin inside stable organosols of maghemite. The sol stability was ensured by ligand adsorption onto the particle surface. Studies of phenylphosphonic acid adsorption are presented. They show a strong interaction between PPA ions and hydroxyl groups of particle surface and through bridging ≡Fe2O2POΦ species. Infrared and Mössbauer spectroscopies as well as quasi- elastic light scattering and transmission electron microscopy were used to characterize the materials.

A microstructural study on surfactant templated silica films is performed by coupling traditional X-Ray Diffraction (XRD) and Transmission Electronic Microscopy (TEM) to Grazing Incidence Small Angle X-Ray Scattering (GISAXS). By this method it is shown that spin-coating of silicate solutions with cationic surfactant cetyltrimethylammonium bromide (CTAB) as a templating agent provides 3D hexagonal structure (space group P63/mmc) that is no longer compatible with the often described hexagonal arrangement of tubular micelles but rather with an hexagonal arrangement of spherical micelles. The extent of the hexagonal ordering and the texture can be optimized in films by varying the composition of the solution.

The mechanical quality factor Qm of 1–3 piezoelectric lead zirconate titanate/epoxy composites with ceramic volume fractions φ ranging from 0.18 to 0.82 has been measured. This range of φ is wider than those previously investigated by other workers. The width-to-thickness ratio of the ceramic phase is sufficiently small that there are no significant mode couplings. The observed Qm agrees well with the prediction of the parallel model. It is found that Qm increases from 34 to 100 as φ changes from 0 to 0.82 and then increases sharply to reach a high value of 600 at φ = 1. Therefore Qm can be tailored to give a wide range of values by varying φ.

Multifunctional nanocomposite coatings and bulk materials have been developed on the basis of a combination of purely organic, as well as hybrid organic-inorganic polymeric matrices and anisotropic synthetic and natural clays. The clays have been chemically modified in such a way that they became compatible to the polymeric matrices. Clay platelets may be separated by modification with an organic molecule that contains two or more charged functional groups. The cations or anions located between the clay sheets are exchanged with one of these organic functional groups, which results in the formation of clay platelets “coated” with charges, thereby causing a molecular dispersion. Depending on the nature of the organic molecule colored or colorless coatings and polymeric bulk materials, containing homogeneously dispersed separated clay platelets, have been obtained.

While retaining the basic functional properties of the materials new and/or improved properties have been introduced. This concerns in particular improved barrier properties, such as a decreased permeability for oxygen and water, improved corrosion resistance and increased thermal stability.

The composition of the wet coating systems is such that they can be properly applied and thermally or photo-chemically cured on various substrates such as glass, steel, aluminum and plastics. The bulk materials can be processed into final product shapes by conventional polymer processing techniques.

The study of organic/inorganic hybrid materials has become an increasingly widespread research focus. The advantage derived from such materials is the combining of two very different compounds which may result in something that bridges the performance gap between the two systems. We have previously reported such hybrid systems prepared by incorporating polyhedral oligosilsesquioxanes (POSS™) into traditional organic polymers by the copolymerization of POSS™ monomers and organic monomers. This presentation will discuss a more convenient method of incorporating POSS™ into a polymer: the blending of POSS™ into organic polymers. The research discussion will focus on the development of the POSS™ macromers used in our studies as well as the POSS™ polymer blends synthesized. One important property enhancement observed is the increase in surface hardness for a POSS™/poly styrene sample.

We present a new way of making macroporous materials using colloidal suspensions of ceramic nanoparticles. We start from a mondisperse emulsion of 0.5 to 3.0 μm diameter oil droplets suspended in an aqueous colloidal dispersion of 80–100 nm silica particles. Upon evaporation of the water, the silica particles form a particulate gel around the emulsion droplets. Removal of the emulsion droplets by dissolution in alcohol and subsequent drying produces a monolithic solid macroporous body. Bulk gels with volume greater than 1 cm3 could be easily produced with this method. Uniform films with thickness of approximately 10 μm have also been made by dip coating of the emulsion-silica colloid mixture. One can also use polystyrene particles as templates in place of the emulsion droplets. Using this approach, we were able to produce highly ordered macroporous titania and silica ceramics with pore sizes around 500 nm and typical dimensions of 3.0 × 2.0 × 0.5 mm3. These dimensions are much larger than those produced using alkoxides. Lower shrinkage associated with particulate gels reduces cracking and increases the structural integrity of the macroporous body.

Organic-inorganic hybrids exhibiting specific properties are easily prepared by incorporation of organic fragments in an inorganic network. Increasing attention is being paid to hybrid silsesquioxane gels, which are prepared by sol-gel hydrolysis condensation of organic molecules containing two or more trialkoxysilyl substituents. These hybrids consist of a mixed three-dimensional network, where the organic fragment, cross-linking siloxane chains, is part of the framework. Owing to the presence of a strong Si-C bond between the organic and the inorganic fragments, highly stable hybrid network are produced in this way. A variety of materials can be produced according to the intrinsic properties of the organic. We report here the preparation of hybrid materials with complexing properties upon hydrolysis-condensation of ligands functionalized by Si (OR)3 groups. New hybrid silica based materials containing malonamide ligands have been prepared by sol-gel hydrolysis condensation of functionalized precursors and have been used as solid phase extractants for the complexation of actinides. This approach is quite different from the classical immobilization procedure of complexing agents. The sol-gel approach allows one to adjust the ligand loading and to achieve some control and some tuning of the ligand environment since the oxide matrix is built around the complexing moieties. These hybrids proved to be highly efficient extracting solids.

In 1994, the U. S. Army initiated a research effort towards an effective material that acts both as a protective barrier and as an active destructive matrix against chemical warfare agents (CWA). We report results on our preparation and evaluation of Reactive Topical Skin Protectants (rTSP's). These creams are composite materials consisting of a base material (TSP) and a reactive moiety. Using an established base of perfluorinated-polyether and perfluoropolyethylene solids we incorporated over 60 reactive components. Classes tested include organic polymers, organic/inorganic hybrid materials, polyoxometallates (POM's), enzymes, inorganic oxides, metal alloys and small molecules. We characterized these materials by light microscopy and FTIR. We determined the efficacy of these materials against both sulfur mustard (HD) and a representative nerve agent, soman (GD), using a penetration cell model coupled to a continuous air monitor and also by in vivo testing. Composite materials with optimum reactive compounds exhibit a 94% reduction of GD vapor break-through after 20 hours (from 9458 ng to 581 ng) and a 3.6 fold increase (from 162 min to 588 min) in the time 1000 ng of GD liquid penetrates through the material. Similar composite materials show a 99% reduction in HD vapor break-through after 20 hours (from 4040 ng to 16 ng), a 2.3 fold increase (from 524 min to >1200 min) in the time 1000 ng of HD vapor penetrates through the material, and an elimination of erythema versus control in an HD vapor challenge. These results indicate that an rTSP that protects against sulfur mustard and nerve agents is within reach.

Spray-coated, R-Si (OR')3 / TMOS (R = epoxide), thin films are being investigated as room temperature curing corrosion resistant coatings for 2024-T3 aluminum alloy. Solid state 1H-13C CP/MAS NMR indicates that primary aliphatic amines and super acids are effective crosslinkers for epoxide groups in aqueous ormosil systems. Incorporation of a crosslinking agent into the coating was found to reduce the cure time of the deposited film from >7 days to approximately 30 min. Accelerated salt spray and filiform corrosion resistance tests were conducted to determine the effects of crosslinking on the corrosion resistance behavior of ormosil thin films. The choice of curing agent was found to influence film structure and corrosion resistance properties. Amine cured thin films were hard and highly adherent to the aluminum alloy substrates, exhibiting excellent bare and filiform corrosion resistance, in addition to good compatibility with organic polymer paint systems. In contrast, the adhesion and corrosion resistance of super acid cured thin films to aluminum alloy substrates was significantly less, producing films which readily delaminated from the substrate. These observations can be related to the film structure.

In pursuit of our goal of forming organic-inorganic hybrid frictional materials, we produced two types of composites, i.e., conventional and hybrid. We formed conventional composites by dispersing fly ash, montmorillonite clay, or pre-formed nano-sized silica particles in phenolic matrix. Hybrid composites were fabricated from sol-gel technique using tetramethylor-thosilicate-phenolic mixtures. We subjected our samples to X-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), in-situ transmission-Fourier transform infrared (ISTA-FTIR), and dynamic mechanical analyzer (DMA) measurements at 40°C < T < 310°C. Our results suggested that the curing behavior of the phenolic polymer was affected by the concentration of the silica and hybrid composites manifested mechanical properties, which were substantially different from that of conventional composites.

Two enzymes, lipase and β-galactosidase, have been encapsulated within sol-gel matrices. Enzymatic activity of encapsulated lipase for hydrolysis and trans-esterification reactions is maintained. Encapsulation yields depend not only on the sol-gel porous texture but also on the water amount added for the sol-gel synthesis and the hydratation history of the enzyme. When the water amount is low, the highly active enzyme conformation generated by the phase separation is frozen during gelation. Escherichia Coli have been also encapsulated. The cellular organization appears to be well preserved. Their β-galactosidase activity seems to be better in wet gels but decreases dramatically upon drying.

Mesoporous materials have attracted considerable interest because of applications in molecular sieve, catalyst, and adsorbent. It will be useful for new functional device if functional molecules can be incorporated into the pore of mesoporous material. However, it is necessary to synthesize new mesoporous materials with controlled large pore size. Recently, new class of mesoporous materials has been prepared using triblock copolymer as a template. In this paper, we reported that hexagonal and cubic structure silicate mesoporous materials can be synthesized through triblock copolymer templating, and their size was controlled by synthesis condition at condensation.

Our main approach to the synthesis and study of hybrid organic/inorganic materials involves incorporating nano-size inorganic polyhedral oligomeric silsesquioxane (POSS) clusters into various polymeric resins. A typical POSS cluster is a discrete silicon and oxygen framework solubilized with organic groups and contains a single reactive site. This lone site of reactivity is used to covalently attach the inorganic macromers pendent to a polymer backbone without causing any crosslinking. 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 motion, polymer properties and morphology. The synthesis of norbornenyl-based (POSS) macromers, their ring opening metathesis copolymerizations with varying amounts of norbornene, and analysis of the effect of the pendent POSS group is presented. Ring opening metathesis polymerization permits the easy synthesis of both random and diblock copolymers. Transmission electron microscopy (TEM) clearly images POSS-rich domains against the POSS-free regions. Major differences in polymer morphology are observed as the amount of inorganic POSS is varied, between random and diblock copolymers, as well as between polymers that differ only in the solubilizing cycloalkyl groups on the POSS cluster.

Mesostructured titanium-oxo/polymer hybrids were obtained by using Ti16O16(OEt)32 (TS) clusters or by aging solutions of Ti alkoxides as precursors. Dendrimers or PEO-based surfactants were used as templating agents. Solids were characterised by XRD, TEM, FTIR and multinuclear liquid and solid (MAS) NMR spectroscopy. Two synthetic approaches are described. In the alkoxide-based systems, the control of the high reactivities of the Ti (IV) metal centers, is essential to obtain ordered mesophases. The assembly of nanobuilding blocks (ANBB) permits to circumvent this high reactivity by using pre-formed Ti-oxo entities. The use of versatile functionalised dendrimers permits to control the reactivity at the surface of the cluster, giving birth to novel ordered architectures.

Two processes for depositing colloidal silica films that can be used as high surface area substrates for DNA arrays are presented. The films boost the hybridization signal above that obtainable from the same lateral area of a “flat” array. In the first process, colloidal silica is deposited directly from solution. In the second, a templating technique is introduced to give added control over the pore size and porosity of the film. Polymer latex is co -deposited with the silica and then pyrolyzed, resulting in larger pores and higher porosity. Both types of films are tested for functional performance with DNA arrays and show promising results.

Organopolysilsesquioxanes have recently gained much interest as materials for low-K dielectrics [1], ceramic precursors [2] and photoresists [3]. Typical sol-gel synthesis of polysilsesquioxanes involves the hydrolysis of organotricholorosilanes and/or organotrialkoxysilanes in the presence of acid or base catalysts and organic solvents. However, under sol-gel conditions most organotrialkoxysilanes do not afford silsesquioxane gels. This limits the range of organic functionalities that can be introduced into these hybrid organicinorganic materials.

Amphiphilic block copolymers were prepared with poly(dimethylsiloxane) (PDMS) as the hydrophobic unit. The hydrophilic block was composed of either a poly (ethylene oxide) or a functionalized polysiloxane unit. The polymer based on polysiloxane blocks only, represents one of the first examples of a new class of surfactants with a purely inorganic Si-O backbone. Beside their potential use as templates for the synthesis of mesostructured inorganic materials, these new polymers offer the possibility of being transformed into porous mesostructured silica-based material by controlled pyrolysis.