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To improve the thermal and mechanical properties of water-based acrylate adhesives, epoxy functional silane oligomer (EFS) was investigated as a crosslinking agent at different curing temperatures from 100 to 140[degrees]C. Water-based acrylate adhesives with different EFS concentrations (0.0-2.0 wt%) were prepared and characterized by Fourier transform infrared spectrometry (FT-IR), colloidal stability, water absorption, mechanical and thermal properties. The thermal and mechanical properties of samples were investigated by means of differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), tensile testing, Izod impact, and dynamic mechanical analysis. The amount of EFS had a significant influence on the crosslinking process and curing temperature. FT-IR and TGA analysis revealed successful crosslinking of EFS with the water-based acrylate adhesive at 100[degrees]C temperature. The use of EFS after different curing processes showed higher tensile strength and lower water absorption. Among the percentage of EPS studied, the use of 1.0 wt% presented the most promising results for the improvement thermal and mechanical properties. In addition, the results obtained in this study provide new insights into the use of EFS as a coupling agent of water-based acrylate adhesives for woodfiber composites, as well as in the particleboard panels industry. KEYWORDS crosslinking acrylate adhesive, formaldehyde-free, functional epoxy silane, mechanical properties, one-component adhesive, 1 | INTRODUCTION Over the last 20 years, the use of thermoset polymers with wood derivates (fibers, laminates, and plywoods) in the automotive sector and in furniture-frame applications has been [...]

Reaction of complex [(ArN)Mo(H)(Cl)([PMe.sub.3]).sub.3] (1) with [BPh.sub.3] and silane [H.sub.3]SiPh affords a new silyl complex [(ArN)Mo([SiH.sub.2]Ph)(Cl)([PMe.sub.3]).sub.2] (3) that catalyses facile H-H/Si-H exchange. EXSY experiments suggest that this exchange does not involve the classical pathways such as oxidative addition of hydrogen or silane to the complex or [sigma]-bond metathesis. It is suggested that the exchange may occur in an FLP cage comprised by the complex and the silane. Key words: hydrogen, silane, imido, molybdenum, EXSY. La reaction du complexe [(ArN)Mo(H)(Cl)([PMe.sub.3]).sub.3] (1) avec le [BPH.sub.3] et le silane [H.sub.3]SiPh permet d'obtenir un nouveau complexe silyle, le [(ArN)Mo([SiH.sub.2]Ph)(Cl)([PMe.sub.3]).sub.2] (3), qui catalyse en douceur l'echange H-H/Si-H. Des experiences EXSY laissent supposer que cet echange ne procederait pas par les voies classiques comme l'addition oxydante d'hydrogene ou de silane au complexe ou la metathese de la liaison [sigma]. Nous posons l'hypothese selon laquelle l'echange s'effectuerait dans une cage dite de <>(PLF) formee par le complexe et le silane. [Traduit par la Redaction] Mots-cles: hydrogene, silane, imido, molybdene, EXSY., Introduction Dihydrogen is the simplest and yet one of the most important molecules, being the integral part of industrial hydrogenation reactions. (1) Activation of its strong and nonpolar H-H bond [...]

High-pressure structures of disilane ([Si.sub.2][H.sub.6]) are investigated extensively by means of first-principles density functional theory and a random structure-searching method. Three metallic structures with P-1, Pm-3m, and C2/c symmetries are found, which are more stable than those of [XY.sub.3]-type candidates under high pressure. Enthalpy calculations suggest a remarkably wide decomposition (Si and [H.sub.2]) pressure range below 135 GPa, above which three metallic structures are stable. Perturbative linear-response calculations for Pm-3m disilane at 275 GPa show a large electron-phonon coupling parameter [lambda] of 1.397 and the resulting superconducting critical temperature beyond the order of [10.sup.2] K. metallization | new phase | solid disilane doi/ 10.1073/pnas.1005242107

Epoxy resin is widely used as an insulation material in many electrical apparatuses because of its excellent electrical and manufacture characteristics. It is usually mixed with filler to improve mechanical and thermal characteristics. In order to qualitatively clarify the effect of fillers on treeing phenomena, treeing tests were performed with epoxy specimens mixed with different kinds of fillers. The property of the interface is also clarified by the treatment of silica filler using silane coupling. Although tree initiation voltage decreased with introducing silica fillers, the fillers prevented the growth of the tree. The effect of filler shape was more significant on round-shape filler than on square-shape filler. Silane coupling treatment to the fillers did not bring a significant change in tree initiation voltage, however, brought a reduction in tree propagation. The change in tree propagation rate was explained by considering the field relaxation and energy dispersion due to branching at the filler-resin interface. Tree propagation along the interface between resin and a quartz plate was observed and analyzed in order to ensure the above explanation. Index Terms--Epoxy resin, filler, treeing, silane coupling treatment, release agent, adhesion property, moisture.

Quantum chemical calculations were used for examining [S.sub.H]2 reaction between methyl radical and methylsilane. Findings reveal the favorable proceeding of the backside mechanism for the [S.sub.H]2 reaction in a wide range of C-Si-C angles.

There is a great interest in electronic transitions in hydrogen-rich materials under extreme conditions. It has been recently suggested that the group IVa hydrides such as methane (C[H.sub.4]), silane (Si[H.sub.4]), and germane (Ge[H.sub.4]) become metallic at far lower pressures than pure hydrogen at equivalent densities because the hydrogen is chemically compressed in group IVa hydride compounds. Here we report measurements of Raman and infrared spectra of silane under pressure. We find that [SiH.sub.4] undergoes three phase transitions before becoming opaque at 27-30 GPa. The vibrational spectra indicate the material transforms to a polymeric (framework) structure in this higher pressure range. Room-temperature infrared reflectivity data reveal that the material exhibits Drude-like metallic behavior above 60 GPa, indicating the onset of pressure-induced metallization. high pressure | hydrogen-rich materials

A comprehensive study of interaction potentials of the prototype silane dimer in terms of HF, MP2 and DFT methods is presented. The studies provide better understanding effects of the repulsion exponent, the binding energy, the equilibrium bond length, and the asymptotic behavior of the intermolecular potentials.

The mechanism of excess electron and hole localizations in radical ions of poly(dimethylsilane) (PDMS) is investigated by means of molecular dynamics (MD) and extended Huckel methods. The geometry of PDMS with a regular all-trans form is fully optimized and the localization of the electron and hole is found after thermal activation.

The synthesis secondary amines, tertiary amines, and silyl enamines in the hydrosilane reduction of secondary amides catalyzed by a triruthenium complex is described.

A facile and efficient method is described for the cleavage of the Ar-Si bond of various aryl trimethyl silanes. These arylsilanes have readily undergone a solvent-free protodesilylation to the corresponding arenes at room temperature, when adsorbed on montmorillonite KSF (mont KSF).

Mechanistic studies have shown that the Lewis acid-promoted allylic rearrangement of [alpha]-silyloxy allylic silanes have proceeded along an ionic reaction pathway involving a contact ion pair. It is shown that the alleviation of steric congestion at the allylic position of the [alpha]-silyloxy allylic silane and stabilization of [[pi].cc] by hyperconjugation is the driving force behind this transformation.

New conditions are described for the preparation of trimethylsilyl-protected 2,2,2-trichloromethylcarbonols from aldehydes and ketones. A one-pot procedure, which avoids the use of strong bases, is described that has given access to 2,2,2-trichloromethylcarbinols.

The Si-C bond breakings in tetramethylsilane (TMS) when interacting with H/[H.sub.2] and the successive H abstractions from Si[H.sub.4]/C[H.sub.4] in the gas mixture of [H.sub.2]/C[H.sub.4]/TMS were explored. The results indicated that the Si-C bond breaking in TMS was caused by H radical.

The influence of the chemical structure of a triethoxysilane (TES), octadecyltriethoxysilane (ODTES), and ODTES/bistriethoxysilylpropyltetrasulfane (TESPT) mixture is investigated using inverse gas chromatography (IGC) at infinite dilution. Thermodynamic results indicate a higher polarity of the silica surface modified with TES as compared to that of the unmodified silica due to new OH groups deriving from the hydrolysis of ethoxy groups of the silane.

The stereocontrolled synthesis of vinyl iodide along two alternative routes is described. The first route has used a standard Roush crotylation protocol, whereas the second method followed an allenyl silane propargylation with unexpected stereochemical consequences.

The thermal [C.sup.2]-[C.sup.6] cyclization of the enyne-allenes and their ring-closed and ring-opened products is described using an ultrafast radical clock. The results have provided a direct evidence for a stepwise mechanism in the [C.sup.2]-[C.sup.6] cyclization of enyne-allenes.

Matrix isolation infrared spectroscopy is used to study the conformations of dimethoxydimethylsilane (DMDMS) by trapping the silane in argon and nitrogen matrixes. Natural bond analysis has indicated that the charge-transfer hyperconjugative interactions have determined the conformational preferences in the molecule.

A study was conducted to study the reaction paths of 73 reactions with well-defined transition states that take place during and after the decomposition of methyltrichlorosilane (MTS). The studies provided insight into reaction pathways, Gibbs free energy barriers and thermodynamic properties of the transition states.

A study was conducted to determine the structures and energies of the gas-phase species generated during and after the various unimolecular decomposition reactions of methyltrichlorosilane (MTS). The studies provided insight into reaction enthalpies, heat capacity and entropies, and Gibbs free energies of various species.

A combination of Brook rearrangement-mediated [3+4] annulation and epoxysilane rearrangement have provided a new methodology for the construction of seven- and eight-membered carbocycles. The chirality transfer of epoxide to the remote positions via formal chiral carbanions through a tandem sequence has provided new aspects of asymmetric synthesis.

The effects of the structure of an alkoxysilane on the early reaction kinetics of sol-gel polymerization are examined in basic and acidic conditions. A high electron density at silicon leads to a low reactivity in basic condition but a high reactivity in acidic conditions and only bis(trimethoxysilylpropyl)amine (BTMSPA) in basic conditions defies these trends, possibly due to the effects of solvation near the reactive silicon site.

The syntheses and characterization of two new push-pull type second-order nonlinear optical (NLO) active isophorone-based alkoxysilane dyes with the same acceptor is reported. Normalized UV-vis spectra demonstrate that the introduction of a diaryl group would help to prevent unfavorable organization of the chromophores.

A novel technique is presented to disperse pristine single-walled carbon nanotubes (SWNTs) in water by ultrasonication in the presence of a thiolated organosilane and subsequent ultracentrifugation. The results have shown that these dispersed SWNTs would be an excellent scaffold for the realization of supramolecular nanoassemblies useful for a variety of applications ranging from nanoelectronics to drug delivery systems.

A concise alternative approach is reported for the synthesis of a range of aryl-substituted cyclohexenediols and cyclohexanetetraols involving the reductive radical arylation of benzene and subsequent treatment with osmium tetroxide. The method is conceptually related to the work of Landais on the desymmetrization of cyclohexadienysilanes generated by Birch reduction or arylsilanes.

Time-resolved kinetic studies of the reaction of silylene, Si[H.sub.2], generated by laser flash photolysis of both silacyclopent-3-ene and phenylsilane are carried out to obtain second-order rate constants for its reaction with C[H.sub.3]Cl. The reaction was studied in the gas phase at six temperatures.

The inhibitory effects of quaternary ammonium silane (QAS) and Biocidal ZF coatings are evaluated against the development of a mixed fungal and bacterial biofilm on silicone rubber tracheoesophageal shunt prostheses in vitro. New strategies are developed for the prevention of microbial colonization of silicone rubber voice prostheses.

A description is provided about the convergent synthesis of three generations of carbosilane dendrimeric carbodiimides. A study was conducted on the extent of site isolation effect of the dendrimers with dilution experiments monitored by FT-IR spectroscopy on the corresponding dendrimeric ureas.

Sulfide radical cations can undergo a fragmentation process involving the cleavage of a bond beta to the positive charge like most radical cations. This reaction, in general, has interesting implications concerning the structural effects upon the fragmentation rate and mechanism and moreover, it leads to carbon radicals and can also have practical applications.

Hydrolysis and condensation of simple trifluorosilanes, HSiF(sub 3) and MeSiF(sub 3), is studied by quantum mechanical methods. The results suggest that the activation energy for hydrolysis by a water dimer is significantly lower than that for hydrolysis by a water monomer.

The photochemical reaction mechanisms of 1,3-silyl migration of allylsilane are investigated using a complete active space comprised of six electrons in six orbitals with the standard 6-31G(d) basis set. It is concluded that the stereochemistry in the photochemical 1,3-silyl migration of allylsilane has a retention preference.

Parent radical cation of nonpolar solvent (alkanes and alkyl chlorides) ionize 9-(trimethylsilyl)xanthenes and 9-(trimethylsilyl)fluorenes in a diffusion-controlled electron transfer. A mobility restriction of the benzylic silane group in positions vertical to the phenyl plane stabilizes the radical cation and accounts for a dissociative radical cations, which undergo C-Si bond fragmentation in the order benzylsilane > xanthenylsilane > fluorenylsilane.

Epoxyallylsilanes containing the bulky tert-butyldiphenylsilyl group undergo, upon treatment with Lewis acid, a sequential rearrangement-cyclization process, which leads stereoselectively to allyl- and vinylsilane functionalized cyclohexanol derivatives. The cyclization follows an ene mechanism, leading to the formation of either allyl-or vinylsilanes depending upon the structure of the starting epoxyallylsilane.

The consequences of double diastereodifferentiation in chiral Lewis base catalyzed aldol additions using chiral enoxysilanes derived from lactate, 3-hydroxyisobutyrate, and 3-hydroxybutyrate was investigated. Trichlorosilyl enolates derived from the chiral methyl and ethyl ketones were subject to aldolization in the presence of phosphoramides, and the intrinsic selectivity of these enolates and the external stereoinduction from chiral catalyst was studied.

The structure of aklylsilane self-assembled monolayers (SAM) on a rough aluminum surface is studied by atomic force microscopy (AFM). AFM studies with different chain lengths shows high friction of disordered short-chain SAMs whereas the heat treatment provides a mechanism for introducing disorder into a SAM.

Formation of a (Z)-derivative from trans-epoxide is explained by the reaction pathway that involves a backside displacement of the epoxide by the alpha-nitrile carbanion and the O-Si bond formation followed by concerted processes involving Brook rearrangement and the anti-mode of eliminative ring fission of the cyclopropane. The result shows the stereochemical course of the reaction by the synthesis of proposed intermediates by an independent route and examination of the reaction to the products.

A report that electroreduction of aromatic ketones with acylimidazoles in the presence of chlorotrimethylsilane (CTMS) and triethylamine (TEA) effected inter- and intramolecular reductive acylation of aromatic ketones, is presented. This electroreduction provides a useful method for the synthesis of aryl alpha-hydroxy ketones and esters.

The photocarrier generation mechanism and mobility in poly[bis(p-n-butylphenyl)silane] (PBPS) thin films doped with a variety of electron acceptors are studied by time-resolving microwave conductivity (TRMC) measurements. It was found that fullerence is a suitable electron acceptor for PBPS as it provides the highest product of photocarrier generation yield and the result shows that the high charge carrier mobility of PBPS polymer makes it a potential material for use in optoelectronic devices.

A novel and efficient strategy was developed to synthesize [difluro(phenylseleno)methyl]-trimethysilane (PhSeCF2-TMS), which was further utilized as a nucleophilic difluoromethylating reagent to incorporate the [difluro(phenylselen)methyl]-trimethysilane into carbonyl compounds in good yield. The resulting PhSeCF2-containg alcohols could be conveniently converted into corresponding difluoromethyl alcohols by a radical deselenylation.

Conformations of trimethoxymethylsilane are studied using matrix isolation infrared spectroscopy and ab initio computation. Trimethoxymethylsilane is trapped in both argon and nitrogen matrixes using heated nozzle effusive sources and a supersonic jet source, in an effort to alter the conformational population in the matrix.

Double asymmetric [3+2]-annulation reactions of chiral beta-silyloxyallylsilanes with chiral 2-tetrahydrofuranyl carboxaldehydes are studied. Transition-state models are proposed to account for the stereoselectivity of the double-stereodifferentuiating [3+2]- annulation reactions.

Talc-like compounds that are formed by the condensation of organotrialkoxy silanes with magnesium hydroxide represent layered hybrid nanomaterials that have a layer thickness of around 1nm, have organic moieties covalently linked to the layer surfaces and are called 'organoclays'. Silsesquioxanes formed by acid treatment of the phenyl-clay comprise a mixture of ladderlike and cagelike structures.

The relative stability and the mechanisms of degradation of four polysilanes, which are reported as active materials in light emitting diodes are investigated theoretically. The correlation of the calculated results with experimental observations suggests that one of the causes of degradation in polysilanes can be the scission of Si-Si bonds in the excited state and that some stabilization is possible when a stable excited state exists.

An efficient methodology is developed for the reductive alkylation of secondary amine with aldehyde and Et(sub 3)SiH using an iridium complex as a catalyst. A variety of secondary amines could be alkylated by allowing them to react with aldehydes and polymethylhydrosiloxane in the presence of an iridium catalyst to afford the corresponding tertiary amines in excellent yields.

The interaction of triethoxysilane (TES) with H-ferrierite (H-FER) and its effects on acidity are investigated by infrared spectroscopy. The silanization process involves contact between the zeolitic surface and TES vapors followed by evacuation steps at increasing temperature up to 773K.

Describing herein the study on the regioselectivity of the reductive silylation involving dissymmetric allylthioethers. The findings shows that THF can be cleaved in mild conditions should be taken into account in the design of new reductive lithiations.

Density functional theory calculations are used to examine the mechanisms of dissociative adsorption of methylsilane on the Si(100)-2 X 1 surface. The findings indicate that the product of Si-H dissociation is the dominating dissociative product whereas methylsilane is a good candidate for the growth of SiC films.

The interaction of triethoxysilane (TES) and bis[3-triethoxysilylpropyl]tetrasulfane (TESPT) with silica has been studied by IR spectroscopy. TES is adsorbed onto silica pretreated at different temperatures, from the gas phase and, also by a liquid-phase procedure.

Gas-phase reactions between silane (SiH4) and water (H2O) are investigated using ab initio calculations at the CCSD(T)/6-311++G//MP2/6-31+G level. It is concluded that providing more energy to the system, SiH4-H2Ocan dissociate atomically and the initial products can further eliminate H2 or H, producing smaller species of molecules SiH-OH, SiH2-O, Si-H2O, and SiO and radicals SiH2-OH, SiH-H2O, HSiO, and HOSi.

Matrix-isolation experiments give evidence that broad-band UV-vis irradiation of an Ar matrix doped with SiH(sub 4) and a group 12 metal atom M (M=Zn, Cd or Hg) induces metal insertion into an Si-H bond to give the silyl metal hydride molecule HMSiH(sub 3) as the primary product. The properties of the HMSiH(sub 3) molecules are compared with those of related species, and consideration is given to how the products are formed.

Four new square-plane rhodium siloxide complexes of the general formula [Rh(cod)(P[R.sub.3'])(OSi[R.sub.3])] (where R = Me, i-Pr, O-t-Bu, R' = Cy, Ph) were synthesized and the structures of three of them were resolved by the X-ray method. [Rh(cod)(P[Cy.sub.3])(OSi[Me.sub.3])] (1) appeared to be a very efficient catalyst for hydrosilylation of allyl glycidyl ether to yield, selectively, 3-glycidoxypropyltriethoxysilane, a commercially important silane coupling agent. Catalytic measurements and stoichiometric experiments of 1 with triethoxysilane suggest a mechanism where an unsaturated Rh-H species is responsible for the catalysis. Key words: rhodium (phosphine) siloxides, hydrosilylation, catalysis.