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The nanosized silica with different morphologies such as sphere, granule, needle, short rod, hollow tubule, has been in turn synthesized by using cetyltrimethylammonium bromide (CTAB) as template and mixed chlorosilane (silicon tetrachloride and trichlorosilane) as silicon source in aliphatic alcohol aqueous solution. The as-prepared products were characterized by x-ray diffraction (XRD), transmission electron microscope (TEM), and Fourier transform infrared spectroscopy (FT-IR), and BET nitrogen adsorption technique was employed for determination of specific surface area of the powdery silica. The formation conditions and mechanism of the nanosized silica with special and diverse shapes are preliminarily discussed.

The compound 5-chloro-1-aza-5-silatricyclo[3.3.3.01,5]undecane (C9H18NSiCl) combines with water to form an association complex with the formula C9H18NSiCl·H2O. Proton NMR studies at various temperatures, concentrations and magnetic fields indicate that this compound exists in solution as an equilibrium mixture of the initial chloride and its association complex with water, a structure for which is proposed. Evidence is provided against a rigid hexacoordinate complex. The equilibrium is shown to correspond to a reversible hydrolysis of C9H18NSiCl which is nucleophilically activated by the intramolecularly coordinating nitrogen present in situ. The reverse reaction is the decomposition of the association complex C9H18NSiCl·H2O to C9H18NSiCl and free water. As a consequence, this paper presents a reversible hydrolysis of a chlorosilane interconverting two directly observable pentacoordinate species without addition of an external nucleophile, and proceeding with retention of configuration at the silicon atom. We further argue that this reaction cannot proceed through a rigid hexacoordinate octahedral intermediate, but could proceed through two non-rigid species, the averaged dynamic behaviour of which is identical to a non-octahedral hexacoordinate transition state.

SiO2-supported silyl chromate catalyst (UCC S-2 catalyst) is an important catalyst for the commercial production of polyethylene. Cann first reported a possible green synthesis route for the preparation of S-2 catalyst through transformation from Phillips catalyst by addition of triphenylsilanol (TPS) to avoid the use of toxic bis(triphenylsilyl) chromate (BC). In this work, this green synthesis route was further investigated by the combination of experimental and theoretical methods. The obtained catalyst was named as PS catalyst based on the incomplete conversion of Phillips catalyst to S-2 catalyst. Polymerization activity of PS1.5 catalyst was higher than that of S-2 catalyst with either TEA or MAO as cocatalyst. The existence of the simultaneously formed hydroxyl group and its coordination to the reduced Cr site was favorable to the PS catalyst, and this might attribute to the higher polymerization activity of PS catalyst than that of S-2 catalyst. A further modification of PS catalyst by a series of alkyl chlorosilane compounds showed that the role of the electron-withdrawing group only limited at a certain distance away from Cr active site. This preliminary study provided a solid basis for a further innovation of PS catalysts and final substitution of S-2 catalyst in commercial processes.

An efficient synthesis of 2-hydroxy-3-[2-oxo-2-phenylethylidene]-2-phenyl-2, 3-dihydro-4 H-furo[3, 2-c]chromene-4(2H)-one is described. This involves the reaction between dibenzoylacetylene and 4-hydroxycoumarine in the presence of NaH (10 mol %) in nearly quantitative yield. Treatment of this heterocyclic system with trimethyl chlorosilane in CHCl(3) leads quantitatively to 4-oxo-3-[2-oxo-2-phenylethylidene]-2-phenyl-3H, 4H-furo[3,2-c]chromene-1-ium chloride. Direct addition of nucleophiles, such as alcohols, amines or trialkyl phosphites to this salt in water as the solvent produces functionalized 2-phenyl-4H-furo[3,2-c] chromen derivatives in excellent yields.

An overview is given on synthesis and structures of new bidentate phosphaalkene ligands [(RMe2Si)2C P]2E (E = O, NR, N−) and (RMe2Si)2C P N(R′) PR′′2. Exceptional properties of these ligands, extending beyond predictable properties of phosphaalkenes are: (i) the N Si bond cleavage of [(iPrMe2Si)2C P]2NSiMe3 with AuI and RhI chloro complexes under mild conditions leading to binuclear complexes of the 6π-delocalised imidobisphosphaalkene anion [(iPrMe2Si)2C P]2N−, and (ii) the chlorotropic formation of molecular 1:2 PdII and PtII metallochloroylid complexes with novel ylid-type ligands [(RMe2Si)2C P(Cl) N(R) PR2]−, and the transformation of a P-platina-P-chloroylid complex into a C-platina phosphaalkene by intramolecular chlorosilane elimination. Properties of the heavier congeners [(RMe2Si)2C P]2E (E = S, Se, Te, PR, P−, As−) and (RMe2Si)2C P E PR′′2 (E = S, Se, Te) are also described.

Polymeric gel composed of high hydrolyzed grade poly(vinyl alcohol) and surface-modified waste fly ash has been synthesized and reported for the first time. Organic chlorosilane has been used as the surface modifier for the as-received fly ash samples for strong interaction with poly(vinyl alcohol). The resultant gels are visually transparent and thermally stable as compared to the virgin poly(vinyl alcohol). These are also mechanically stronger than the base polymer and as-received fly ash/poly(vinyl alcohol) gels due to better polymer-surface-modified fly ash interaction as reflected from their viscometric results.

A novel silicon-containing resin (ESA resin) was successfully synthesized by the condensation reaction of lithium arylacetylide with chlorosilane in high yields. The resin was characterized by the techniques of FTIR, 1H-NMR, 29Si-NMR, and gel permeation chromatography. Thermal cure process was monitored by DSC and FTIR methods. This resin could melt at around 100°C and thermally cured at 200–250°C with low exothermal enthalpy. Owing to the high aryl groups containing and the complete crosslinking of ethynyl groups, the cured ESA resin exhibited excellent thermal stability and high char yield. The decomposition temperature of the cured resin was at 510°C, and the residue yield at 900°C was 82.9% in N2. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010

Ultra-fine silicalite-1 particles were modified with four kinds of chlorosilanes (dodecyltrichlorosilane, octyltrichlorosilane, hexadecyltrichlorosilane and octadecyltrichlorosilane) and characterized by FI-IR, TGA, contact angle measurements and BET analysis. It was found that the surface hydrophobicity of silicalite-1 particles was improved significantly as the alkyl group was strongly bonded to the particle surface. Modified silicalite-1 particles were incorporated into PDMS (poly(dimethylsiloxanediol)) membranes, which were applied for the pervaporation separation of ethanol/water mixtures. The effect of surface properties, zeolite loading and operation conditions on pervaporation performance of the membranes was investigated. The separation factor of PDMS membranes filled with modified silicalite-1 increased considerably compared with that filled with unmodified ones, and the total flux decreased with increasing zeolite loading. The solution and diffusion selectivity of hybrid membranes were also measured to explain the pervaporation properties of silicalite-1 filled PDMS membranes. It was found that modification of silicalite-1 with dodecyltrichlorosilane effectively improved the solution and diffusion selectivity of silicalite-1 filled PDMS membranes with high zeolite loading. This may be attributed to the high surface hydrophobicity of modified silicalite-1 and its good integration with PDMS membranes. Both the high separation factor and solution selectivity indicated that modification of silicalite-1 with chlorosilanes was an effective method to improve the selectivity of silicalite-1/PDMS hybrid membranes for ethanol.

We report a new “grafting to” technique for the functionalization of silica particles with anionically produced polymers. It is based on a two-step procedure. In the first step the silica nanoparticles were modified with multifunctional chlorosilanes. This procedure allows replacing the original Si−OH surface groups by Si−Cl groups. In the second step the anionically synthesized polymers were linked to the Si−Cl functionalized nanoparticle surface. Both the chlorosilane functionalization of the nanoparticles and the subsequent reaction with living polymer can be carried out without irreversible particle aggregation. This was proved by examining the reaction products with static and dynamic light scattering as well as small-angle X-ray scattering. The polymer linking event is accompanied by termination reactions, most likely due to residual Si−OH groups. Therefore, the raw products were purified by a simple fractionation procedure. The examination of the products by size exclusion chromatography showed tha...

Polyfunctional linear poly[(sodiumoxy)methylsilsesquioxanes] are obtained via the hydrolytic polycondensation of sodiumoxymethyl(dialkoxy)silanes. Blocking of sodiumoxy groups with vinyl(dimethyl)chlorosilane is employed to obtain vinyl(dimethyl)siloxane replicas of polyfunctional matrices. The linear structure of the polymers is studied by GPC, NMR spectroscopy, and elemental analysis. The specific properties of poly[vinyl(dimethylsiloxy)methylsilsesquioxane] are investigated and are shown to be primarily related to an abnormally dense organization of polymer coils in solutions.

Insertion reactions of dimethylsilylene (Me(2)Si:) into the silicon-chlorine bond of various substituted chlorosilanes have been computationally studied by using DFT calculations with a 6-31++G(d,p) basis set. All of the insertions investigated herein were exothermic (more than 40 kcal mol(-1)) and proceeded via three-membered cyclic transition states (TS) with one substituent of a chlorosilane in the ring plane and two other substituents out of the plane. Among the two possible concerted insertion pathways, the pathway via a TS with a silylene lone-pair orbital approaching a chlorosilane silicon atom was preferred. Important nucleophilic interactions of silylene lone-pair orbitals with anti-bonding sigma orbitals of Si-Y (in plane) were supported by carrying out a natural bond orbital (NBO) analysis of the reaction. A radical pathway through the initial abstraction of chlorine from chlorosilane by the silylene cannot compete with the preferred concerted pathway. Systematic calculations for SiMe(2) insertion into various chlorosilanes (YR(2)SiCl; Y (in-plane substituent) = H, Me, NH(2), OH, F, SiH(3), PH(2), SH and Cl; R (out-of-plane substituent) = H, Me, iPr and tBu) have revealed remarkable substituent effects on activation free energies (DeltaG(double dagger)). In-plane (Y) substituent effects were mostly electronic. Electron-withdrawing substituents accelerate the insertion through enhanced nucleophilic interaction between silylene lone-pair orbitals with the sigma*(Si-Y) orbital at the TS. The DeltaG(double dagger) values correlate with the sigma(I) constants as a scale of the inductive effect of Y. Out-of-plane (R) substituent effects are mainly steric, and bulky substituents increase the activation free energy . Correlation of the DeltaG(double dagger) values with Taft's steric substituent constants (E(s)) was observed. There was no significant difference in the out-of-plane substituent effects between the electron-withdrawing Cl and the electron-donating Me groups.

Carbosilane dendrimers can be used as soluble supports for organic synthesis, since their structure allows separation of excess reagents from the supported products, eventually yielding products of high purity and in high yield, as in solid-phase organic synthesis (SPOS). In previous studies often loss of dendritic material during filtration was observed, due to the rather flexible structure of the conventional dendrimers. In order to improve the diafiltration retention of the carbosilane dendrimers, the synthesis of carbosilane dendrimers based on more rigid-core molecules was investigated. Both 1,3,5-tris(4-bromophenyl)benzene 1 and tetrakis(4-bromophenyl)silane 2 were selected on the basis of their rigid structure and suitable functional groups for further functionalization using organolithium chemistry. An optimized halogen lithium exchange (HLE) protocol was developed for the synthesis of 2 via 1-bromo-4-lithiobenzene. This protocol involves reaction of an aryl bromide with n-BuLi at room temperature, followed by partial removal of the solvent by evaporation (70%, v/v), addition of pentane to promote precipitation of the aryl lithium compound, and centrifugation and removal of the solvent to obtain, after repeating the last two steps once, the wet aryl lithium compound in pure form. This HLE protocol was proven to be effective for mono- and dilithiation, as well as for polylithiation reactions of aryl bromides. Furthermore, the rigid tris(4-bromophenyl)chlorosilane wedge 3 was synthesized to add a rigid generation to the prepared core molecules, and bromotriallylsilane 4 was synthesized for the introduction of triallylsilyl moieties on the periphery of the core molecules. With these four building blocks several rigid-core carbosilane dendrimers were synthesized, which can be applied as better retainable soluble supports for organic synthesis in a diafiltration setup

We have developed organic-inorganic silicophosphate and silicophenylphosphite hybrid materials by means of alcohol condensation between organically modified alkoxysilane and anhydrous phosphoric or phosphonic acid under a solventless, catalyst-free, low-temperature, one-pot condition. The hybrid exhibits a low-melting property and is chemically more durable than that prepared by using a nonaqueous acid-base reaction between anhydrous phosphoric acid and organically modified chlorosilane. 29Si and 31P NMR analyses have shown that the alcohol condensation yield was around 80%. Quantum chemical calculations have also performed in order to clarify the chemical durability improvement of the hybrids.

An efficient synthesizing procedure of photoluminescent silicon nanocrystals is demonstrated by means of ultrasound assisted electrochemical octyltrichlorosilane reduction that produces octane terminated Si nanocrystals in a single step. The described procedure allows one to make Si nanocrystals with alkyl surface termination and is clean, relatively simple, and potentially scalable to industrial quantities. High resolution transmission electron microscopy, energy dispersive X-ray spectroscopy, UV-vis absorbance, Fourier transform infrared spectroscopy, and photoluminescence spectroscopy are employed to characterize the synthesized photoluminescent Si nanocrystals. Resulting octyl termination provides a stable passivation and could serve as a platform for further particle functionalization. Electrochemical chlorosilane reduction potentially could address the requirement for stable photoluminescent Si nanocrystals in diverse applications.

Recently we reported a simple method for obtaining both monolayer thickness and surface patterning using self-assembled monolayers (SAMs). Here we presented a straightforward method for controlling the formation of SAMs over surfaces useful for both chemical and biological applications. Atomic force microscopy (AFM) has been used to investigate the growth mechanism and formation of octadecylsiloxane (ODS) films obtained using a less-reactive silane; octadecyltrimethoxysilane (OTMS). SAMs formation from both OTMS and octadecyltrichlorosilane (ODTS) differ in the hydrolysis step where ODTS results in hydrochloric acid formation, which may affect the delicate features on surfaces. On the other hand, OTMS does not show this behavior. In contrast to monolayer formation from chlorosilane precursors, methoxysilane SAMs have been studied less extensively. Our observations highlight the importance of controlling water content during the formation of ODS monolayers in order to get well-ordered SAMs. We have also seen that, like ODTS, OTMS exhibits monolayer growth through an island expansion process but with a comparatively slow growth rate and different island morphology. The average height of islands, surface coverage, contact angle and root-mean-square (RMS) roughness increase with OTMS adsorption time in a consecutive manner.

Calix[4]arenes having multiple silyl groups on the upper (wide) rim were prepared from the corresponding bromocalixarenes by halogen-metal exchange with t-BuLi followed by silylation. The best results were obtained using the clear supernatant from a mixture of chlorosilane and triethylamine. With the higher molecular weight chlorosilanes, an aqueous workup was replaced by a filtration through a column of silica gel. p-(Trimethylsilyl)calixarene 17, the silicon analogue of the well-studied p-tert-butylcalixarene 1, formed a crystalline complex with toluene having a toluene molecule in the cone cavity with the toluene methyl protruding out at an angle.

Synthesis of 2 nd generation dendritic polymeric materials via anionic polymerization procedures in combination with chlorosilane chemistry, consisting either from one polydienic segment (homopolymers) or from two chemically different polydienic components (copolymers), is described. The polydienes used were poly(butadiene) (PB) with ∼90% 1,4-isomerism and poly(isoprene) (PI) with increased 3,4-isomerism (∼60%). Molecular characterization of intermediate products and the final dendritic materials was made with Gel Permeation Chromatography (GPC), Membrane and Vapour Pressure Osmometry (MO and VPO respectively), Gas Chromatography -Mass Spectroscopy (GC-MS) and 1 H-Nuclear Magnetic Resonance ( 1 H-NMR) Spectroscopy, leading to the conclusion that they can be considered model polymers. Morphological studies solely with Transmission Electron Microscopy (TEM) have been conducted on two of the four synthesized copolymer samples exhibiting microphase separation between the two polydiene segments.

Mono- and dilithium salts of [3,3'-Co(1,2-C(2)B(9)H(11))(2)](-), (1(-)), react with different chlorosilanes (Me(2)SiHCl, Me(2)SiCl(2), Me(3)SiCl and MeSiHCl(2)) with an accurate control of the temperature to give a set of novel C(c)-mono- (C(c) = C(cluster)) and C(c)-disubstituted cobaltabis(dicarbollide) derivatives with silyl functions: [1-SiMe(2)H-3,3'-Co(1,2-C(2)B(9)H(10))(1',2'-C(2)B(9)H(11))](-) (3(-)); [1,1'-mu-SiMe(2)-3,3'-Co(1,2-C(2)B(9)H(10))(2)](-) (4(-)); [1,1'-mu-SiMeH-3,3'-Co(1,2-C(2)B(9)H(10))(2)](-) (5(-)); [1-SiMe(3)-3,3'-Co(1,2-C(2)B(9)H(10))(1',2'-C(2)B(9)H(11))](-) (6(-)) and [1,1'-(SiMe(3))(2)-3,3'-Co(1,2-C(2)B(9)H(10))(2)](-) (7(-)). In a similar way, the [8,8'-mu-(1'',2''-C(6)H(4))-1,1'-mu-SiMe(2)-3,3'-Co(1,2-C(2)B(9)H(9))(2)](-) (8(-)); [8,8'-mu-(1'',2''-C(6)H(4))-1,1'-mu-SiMeH-3,3'-Co(1,2-C(2)B(9)H(9))(2)](-) (9(-)) and [8,8'-mu-(1'',2''-C(6)H(4))-1-SiMe(3)-3,3'-Co(1,2-C(2)B(9)H(9))(1',2'-C(2)B(9)H(10))](-) (10(-)) ions have been prepared from [8,8'-mu-(1'',2''-C(6)H(4))-3,3'-Co(1,2-C(2)B(9)H(10))(2)](-) (2(-)). Thus, depending on the chlorosilane, the temperature and the stoichiometry of nBuLi used, it has been possible to control the number of substituents on the C(c) atoms and the nature of the attached silyl function. All compounds were characterised by NMR and UV/Vis spectroscopy and MALDI-TOF mass spectrometry; [NMe(4)]-3, [NMe(4)]-4 and [NMe(4)]-7 were successfully isolated in crystalline forms suitable for X-ray diffraction analyses. The 4(-) and 8(-) ions, which contain one bridging -mu-SiMe(2) group between each of the dicarbollide clusters, were unexpectedly obtained from the reaction of the monolithium salts of 1(-) and 2(-), respectively, with Me(2)SiHCl at -78 degrees C in 1,2-dimethoxyethane. This suggests that an intramolecular reaction has taken place, in which the acidic C(c)-H proton reacts with the hydridic Si-H, with subsequent loss of H(2). Some aspects of this reaction have been studied by using DFT calculations and have been compared with experimental results. In addition, DFT theoretical studies at the B3 LYP/6-311G(d,p) level of theory were applied to optimise the geometries of ions 1(-)-10(-) and calculate their relative energies. Results indicate that the racemic mixtures, rac form, are more stable than the meso isomers. A good concordance between theoretical studies and experimental results has been achieved.

The synthesis of a series of H-shaped A2BC2 terpolymers (Janus-H terpolymers), where A is poly(dimethylsiloxane) (PDMS), B polybutadiene (PBd), and C polystyrene (PS), is presented. The synthetic approach involves (a) the selective reaction of lithium PDMS alkolate with the two chlorosilane groups of the heterofunctional linking agent [(chloromethylphenyl)ethyl]methyldichlorosilane (CMPEMDS) and (b) the linking reaction of the benzyl chloride group, which remained intact, with the living star (PS)2PBd-DPHLi. The synthesis of the living miktoarm star is achieved by (a) the selective reaction of the PSLi chains with the two chlorines of the linking reagent 4-(dichloromethylsilyl)diphenylethylene (DCMSDPE), (b) the addition of sec-BuLi to the double bond of the DPE group, and (c) the polymerization of Bd, followed by end-capping of the living end with one monomeric unit of DPE. The micellization behavior of the Janus-H terpolymers was studied in methyl ethyl ketone, a selective solvent for the outer branches...

Styrenic single and double star-tailed macromonomers were synthesized by selective reaction of living homo/miktoarm stars with the chlorosilane groups of 4-(chlorodimethylsilyl)- and 4-(dichloromethylsilyl)styrene, respectively. The in situ anionic homopolymerization of macromonomers with sec-BuLi and copolymerization with butadiene and styrene, led to single/double homo/miktoarm star-tailed molecular brushes and combs, as well as a block copolymer consisting of a linear polystyrene chain and a double miktoarm (PBd/PS) star-tailed brush-like block. Molecular characterization by size exclusion chromatography, size exclusion chromatography/two-angle laser light scattering, and NMR spectroscopy, revealed the high molecular/compositional homogeneity of all intermediate and final products. These are only a few examples of the plethora of complex architectures possible using the above macromonomers. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 1826–1842, 2008

This review summarizes the advancements in the development of strategies to construct N-silylmethylamides, -lactams, -imides, -carbamates, and -ureas. The N-alkylation of the amide group by halomethylsilanes HalCH2SiX3 and the acylation of N-(silylmethyl)amines by acids and their derivatives RC(O)Y (Y = OH, Hal, OAlk, OC(O)R) were analyzed. The formation of carbanion at α-position of nitrogen atom and its subsequent reaction with chlorosilane was discussed.

Cyclopentyl- and cyclohexyl-substituted polysiloxanes terminated with amino groups were prepared. Initially, the cycloalkene and dichlorosilane were reacted at high pressure (approx. 250 psi) and high temperature (120 °C) to yield the cycloaliphatic dichlorosilane in a two-step process. Both the mono- and disubstituted chlorosilane monomers underwent an oligomerization to produce cyclic oligomers of low molecular weight (≈2 000 g mol -1 ). Amine-terminated polysiloxanes were produced via a base-catalyzed ring-opening polymerization of the cyclic oligomers with 1,3-bis(3-aminopropyl)tetramethyldisiloxane to yield low molecular weight polysiloxanes (≈9 000 g mol -1 , amine equivalent weight = ≈4 300 g equiv. -1 ). The polysiloxanes were characterized by 1 H and 29 Si NMR, and Fourier transform-infrared spectroscopy (FT-IR). The amine-terminated polysiloxane was mixed with a cycloaliphatic epoxy-functionalized cycloaliphatic polysiloxane in order to produce crosslinked epoxy-amine films. The mechanical and physical properties of the film were evaluated and afford a glass transition of the material was 29.5 ± 0.7 °C for the cyclopentyl-substituted polysiloxane and 38.6 ± 0.7 °C for the cyclohexyl-substituted polysiloxane. Evaluation of pull-off adhesion indicated that 0.5 MPa of normal force was required to remove the epoxy/ amine film from an aluminum substrate.

The synthesis and characterization of solution processable, semi-fluorinated perfluorocyclobutyl (PFCB) aryl ether polymers possessing covalently bound pendant polyhedral oligomeric silsesquioxanes (POSS) cages is reported. The synthesis of POSS aryl trifluorovinyl ether (TFVE) monomers was accomplished by the condensation of commercial monosilanolalkyl-POSS with a TFVE-functionalized chlorosilane. POSS TFVE monomers were elucidated by 1H, 19F, 13C, and 29Si NMR spectroscopy, ATR-FTIR analysis, and elemental (C, H, and F) combustion analysis. Bulk thermal copolymerization of POSS TFVE monomers afforded random and block PFCB aryl ether copolymers functionalized with various POSS loadings. Quantitative monomer conversion was monitored by 19F NMR, which produced copolymer number-average molecular weights (Mn) of (19.5−24.9) × 103 (in CHCl3 using polystyrene as standard) determined by gel permeation chromatography (GPC). Thermal properties of POSS PFCB aryl ether copolymers were evaluated by differential scan...

Surface hydrophilisation and effective k-value degradation have been reported in literature after direct-CMP of high porosity SiOC films (without a protective capping layer). In the sequel, attempts to restore ultra low-k (ULK) material initial properties after a standard CMP and post-CMP cleaning process are reported. Annealing treatment has shown to be valuable to remove residual organics and water absorbed at the ultra low-k material surface after direct-CMP. However, as the hydrophilicity of the polished surface remains unchanged, it does not prevent moisture uptake, leading to an increase in k-value with time. Therefore, in order to restore hydrophobic properties and to stabilize the surface in time, three silylating agents - containing chlorosilane reactive groups (-SiMe"nCl"3"-"n) as well as hydrophobic methyl functions (-CH"3) in their structure - have been employed in liquid, gas or dense CO"2 phases on the CMP-induced damaged ULK layers. While each of these organic treatments is efficient to restore hydrophobicity on post-CMP ULK surfaces, only one of them proved to be able to keep the k-value low (comparable to the ULK pristine k-value) and stable in time, without inducing significant change in porosity of the ULK material.

In this paper, we present a new approach for protecting metallic lithium surfaces based on a reaction between the thin native layer of lithium hydroxide present on the surface and various chlorosilane derivatives. The chemical composition of the resulting layer and the chemistry involved in layer formation were analyzed by polarization modulated infrared reflection absorption spectroscopy (PM-IRRAS), X-ray photoelectron spectroscopy (XPS), and energy dispersive X-ray analysis (EDX). Spectroscopy shows the disappearance of surface hydroxide groups and the appearance of silicon and chloride on the lithium surface. Differential scanning calorimetry (DSC) and electrochemical impedance spectroscopy (EIS) show that this surface treatment protects the lithium from certain gas-phase reactions and is ionically conductive.

Highly efficient O-silylation of alcohol with vinylsilane was developed using a catalyst system consisting of [(COE)(2)RhCl](2) and HCl. In this reaction, a key intermediate is chlorosilane, generated from vinylsilane and HCl, which can be regenerated in the catalytic cycle. Various alcohols and vinylsilanes were applied to the preparation of silyl ether compounds with this catalyst system.

A SiC epitaxy process based on chlorosilane/propane chemistry has been successfully transferred from a single-wafer R&D system to a multi-wafer CVD reactor. The optimized process results in very smooth epi surface (RMS~0.24nm) and minimum surface pits (less than 0.5/cm2). Both n-type and p-type doping in a wide range are demonstrated using nitrogen and aluminum, respectively. The high performance benchmarks for thickness uniformity (intra-wafer variation

Organically-modified silicate-phosphate and silicate-phosphite copolymers were prepared through nonaqueous acid–base reaction. The inductive effect of the organic substituent of the starting materials such as organically-modified chlorosilane and phosphorous acid on the acid–base reaction was investigated by 31P NMR measurement and ab initio molecular orbital calculation. The condensation reaction takes place by nucleophilic addition of phosphate ion (or phosphite ion) to chlorosilane through SN2 mechanism to form silicate-phosphate (or phosphite) network. The reactivity of the acid–base pair can be controlled by changing the inductive effect of the organic substituents on the starting materials.

The (2 + 2 + 2) cyclotrimerization of 1-iso- quinolinyl-1,7-octadiyne with benzonitrile catalyzed by CpCo(CO)2 opened a new pathway for a synthe- sis of unsymmetrical axially chiral bipyridine N,N'- dioxides. The N,N'-dioxide 3a was found to be highly catalytically active and enantioselective for the asymmetric allylation of aldehydes with allyltri- chlorosilane. The allylation took place with even 1 % of the catalyst with an enantioselectivity up to 87 % ee.

Ortho lithiation of acetylferrocene and propionylferrocene followed by addition of chlorosilane and diiodoethane was totally enantioselective when a chiral methoxy−imino auxiliary was used as an easily removable ortho-directing group. Enantiopure (R)-o-iodoacetylferrocene and (R)-o-iodopropionylferrocene were obtained. The structure of (R)-o-iodoacetylferrocene was confirmed by X-ray crystallography.

Adhesion at the fiber-matrix interface of a composite is often influenced by a combination of factors such as mechanical interlocking, physicochemical interactions, and chemical bonding in the fiber-matrix interphase region. We demonstrate the use of an approach using self-assembled monolayers (SAMs) for studying the impact of one of the factors, chemical bonding, on the overall adhesion of the glass-fiber/matrix interface. Transformation of these monolayer surfaces using conventional chemistry with a focus on the creation of a terminal functional group that interacts with epoxy resin is reported. The modified surfaces were characterized by ellipsometry, X-ray photoelectron spectroscopy, and contact angle techniques for chlorosilane coverage, and in situ conversion. The adhesion of diglycidyl ether of bisphenol-A resin to modified SAMs on E-glass fibers was measured by performing single-fiber fragmentation test. The extent of adhesion between the fiber and matrix was found to be dependent on the type of functional group at the terminal end of the SAM in contact with the epoxy matrix. Methyl terminal group resulted in the least adhesion, while amine terminal groups resulted in the most adhesion. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007

We report the Synthesis of first generation dendritic homopolymers consisting of either poly(butadiene) (PB) of 1,4-microstructure or poly(isoprene) enriched in 3,4-microstructure (at least 55% PI3,4). The main aspect was the synthesis of polymers exhibiting high molecular and compositional homogeneity. The preparation of these materials was achieved via anionic polymerization techniques in combination with chlorosilane chemistry. The molecular characterization of the final dendritic materials was made via size exclusion chromatography (SEC), membrane osmometry (MO), dilute solution viscometry and H-1 nuclear magnetic resonance (NMR) spectroscopy, leading to the conclusion that they can be considered as model polymers. The conformational properties of the synthesized dendritic polymers were studied by means of analytical theory and Monte Carlo simulations using coarse graining models with the same number of segments. The radii of gyration and the length of the branches of zeroth and first generations were calculated via lattice, off-lattice algorithms, and renormalization group techniques. The theoretical findings were compared with the respective results of star polymers with the same functionality and equivalent branch lengths. (c) 2006 Elsevier Ltd. All rights reserved. Polymer

4-Silacyclohexan-1-ones 1a–1c, 4-silacyclohexan-1-one oximes 2a–2c, 1,4-azasilepan-7-ones 3a–3c, 1,4-azasilepanes 4a–4c, and 2-bromo-4-silacyclohexan-1-ones 5a and 5b were prepared in multistep syntheses, starting from trimethoxypropylsilane. All of these compounds represent C-functional (R2C═O, R2C═N–OH, R–NH(C═O)–R, R2NH, or R3C–Br) silicon-containing heterocycles that contain Si–MOP, Si–DMOP, or Si–TMOP moieties (MOP = 4-methoxyphenyl; DMOP = 2,6-dimethoxyphenyl; TMOP = 2,4,6-trimethoxyphenyl), which can be cleaved under mild conditions by protodesilylation. As a proof of principle, compounds 3a–3c were transformed quantitatively and selectively into the chlorosilane 6 (treatment with hydrogen chloride in dichloromethane). Thus, the C- and Si-functional compounds 1a–1c, 2a–2c, 3a–3c, 4a–4c, 5a, and 5b represent versatile building blocks for synthesis.

The first highly enantioselective silicon Lewis acid catalyst for an asymmetric organic transformation has been developed. The catalyst derives its activity from the strain induced in the silicon center by virtue of being constrained in a five-membered ring. A simple tridentate ligand has been developed and the derived chlorosilane complex catalyzes the Diels–Alder cycloaddition of methacrolein and cyclopentadiene with 94% ee.

Epitaxial growth of SiC films was performed on 4H SiC n+ substrates utilizing a chlorosilane/propane chemistry in both single wafer and batch CVD systems. Variations of the chlorosilane flow under fixed conditions of gas composition, temperature and pressure resulted in growth rates between 4 to 20 μm/hr. Fixing the chlorosilane flow rate to achieve a growth rate of approximately 4 μm/hr, the effects of temperature, pressure and gas composition on background dopant incorporation, epitaxial layer uniformity and epitaxial defect generation were investigated. Intentional n and p-type doping has been demonstrated over the carrier range 1×1018-1×1020/cm3. This paper presents the first reported of use of chlorosilane precursors to grow high quality undoped, n and p doped SiC epilayers.

We have found that the surface and bulk solution properties in a microfabricated device affect the degree and probability of electrostretching of DNA molecules. Using lambda phage DNA, we found that significantly hydrophilic surfaces between the electrodes decrease the efficiency of stretching. Surfaces treated with higher silane (trimethylchlorosilane) concentrations performed better presumably due to the decreased nonspecific adsorption of DNA on these surfaces compared to their more hydrophilic counterparts. The shape and dimensions of the electrodes also affected the efficiency of stretching. Both liftoff and metal etching methods produced electrodes with random microscopic peaks along the electrode's edge and were poorly suited for stretching. Annealing the electrodes (450 degrees C for 10 min) removed most of these peaks and allowed for more controlled stretching to be obtained. We also found that thin electrodes (65 nm) gave close to a 90% success rate of DNA stretching but stretching with thick electrodes (350 nm) produced only a 20% success rate.

Three 6-miktoarm star (6μ-star) copolymers [PS(P2MP)5] of styrene (S) and 2-methyl-1,3-pentadiene (2MP) were synthesized by anionic polymerization and controlled chlorosilane chemistry, using high vacuum techniques. In all cases [Mw = 103 kg/mol, [S] = 44% (v/v); Mw = 91.1 kg/mol, [S] = 53% (v/v); Mw = 224 kg/mol, [S] = 92% (v/v)] the P2MP exhibited high 1,4-microstructure (∼99%). Molecular characterization (size-exclusion chromatography, membrane osmometry, low-angle laser light scattering, and NMR) revealed high molecular weight/composition homogeneity, and structural analysis (differential scanning calorimetry, transmission electron microscopy, and small-angle X-ray scattering) showed highly ordered patterns. The deviations from predictions based on Milner's morphological model are much more pronounced than that of PS(P2MP)2 and PS(P2MP)3 miktoarm stars, which we attribute to greater crowding of the arms for these highly branched molecules.

An organic−inorganic hybrid material of phenylsilicophosphate was prepared through the solventless and catalyst-free nonaqueous acid−base reaction of orthophosphoric acid and phenyl-modified chlorosilane. The 31P NMR results showed that the silicophosphate is constituted of an alternating (POOPh2SiO)n− network, which is expected to be very homogeneous at an atomic level. It was found that the condensation took place through the nucleophilic addition of the phosphate ion to the organochlorosilane, that is, an SN2 reaction mechanism. The electron-withdrawing property of the phenyl group attached to the central silicon, hence, forwarded the formation of the silicophosphate network.

Asymmetric 1,4-addition of arylzinc chlorides to (E)-3-arylpropenals proceeded with high enantioselectivity in the presence of a rhodium/(R)-binap catalyst and chlorotrimethylsilane to give, after hydrolysis, high yields of the corresponding 3,3-diarylpropanals of 98–99% ee. The presence of the chlorosilane is essential for high yields of the 1,4-addition products.

A series of novel four-arm A2B2 and A2BC and five-arm A2B2C miktoarm star polymers, where A is poly(dimethylsiloxane) (PDMS), B is polystyrene (PS), and C is polyisoprene (PI), were successfully synthesized by the combination of chlorosilane and benzyl chloride linking chemistry. This new and general methodology is based on the linking reaction of in-chain benzyl chloride functionalized poly(dimethylsiloxane) (icBnCl–PDMS) with the in-chain diphenylalkyl (icD) living centers of PS-DLi-PS, PS-DLi-PI, or (PS)2-DLi-PI. icBnCl–PDMS was synthesized by the selective reaction of lithium PDMS enolate (PDMSOLi) with the chlorosilane groups of dichloro[2-(chloromethylphenyl)ethyl]methylsilane, leaving the benzyl chloride group intact. The icD living polymers, characterized by the low basicity of DLi to avoid side reactions with PDMS, were prepared by the reaction of the corresponding living chains with the appropriate chloro/bromo derivatives of diphenylethylene, followed by a reaction with BuLi or the living polymer. The combined molecular characterization results of size exclusion chromatography, 1H NMR, and right-angle laser light scattering revealed a high degree of structural and compositional homogeneity in all miktoarm stars prepared. The power of this general approach was demonstrated by the synthesis of a morphologically interesting complex miktoarm star polymer composed of two triblock terpolymer (PS-b-PI-b-PDMS) and two diblock copolymer (PS-b-PI) arms. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 6587–6599, 2006

A novel sol-gel-derived preceramic polymer, namely poly(organosilyl)carbodiimide, was synthesized for fabrication of thermally stable amorphous Si-C-N membranes. The gelation process as well as the viscosity of the poly(organosilyl)carbodiimide was adjusted for spin coating by reacting a mixture of alkyl and dialkyl chlorosilane monomers with bis(trimethylsilyl)carbodiimide. The polymeric precursor film was successfully fabricated on a porous substrate by solvent-free spin coating, subsequently converted into a mesoporous amorphous Si-C-N thin film by pyrolysis at 1000°C in Ar. SEM observation as well as N2 sorption isotherm analysis exhibited the formation of meso-pore channels within the amorphous thin layer. These results indicate that the novel poly(organosilyl)carbodiimide developed in this study is suitable for fabricating meso-porous amorphous membranes in the ternary Si-C-N system and with high thermal and chemical stability.

Difunctional disilanes of the general type XR2SiSiR2X (1–5) (X = OMe, H; R = Me, Ph, H) have been synthesized by electrolysis of the appropriate chlorosilanes XR2SiCl in an undivided cell with a constant current supply and in the absence of any complexing agent. Reduction potentials of the chlorosilane starting materials derived from cyclic voltammetry measurements were used to rationalize the results of preparative electrolyses. Organofunctional silanes of the general formula MeO(Me2)SiC6H4Y (6a–c, 7) were subsequently obtained by the reaction of sym-dimethoxytetramethyldisilane (1) with NaOMe in the presence of p-functional aryl bromides BrC6H4Y (Y = OMe, NEt2, NH2).

Sol–gel materials that swell six times their dried volume when placed in organic solvents were prepared using the bridged silsesquioxane bis(trimethoxysilyethyl)benzene through base catalysis by tetrabutyl ammonium fluoride. Prior to drying the gels, water and catalyst were rinsed from the solvated matrix and residual silanol groups were derivatized with a chlorosilane (R–Si(CH 3 ) 2 Cl). The swelling behavior was completely reversible when the materials are dried at elevated temperature. Swelling is highly dependent on the processing conditions, including the choice of solvent and catalyst. There is no preferential adsorption of solute molecules to swelled sol–gels despite the diversity of chlorosilanes used to derivatize the materials.

In the article Part I of this work durability and separation properties for several types of glass membranes in aggressive gas environment have been evaluated. A surface modified glass membrane (modified with (heptadecafluoro-1,1,2,2-tetrahydrodecyl) dimethyl chlorosilane, Pf-C10), proved to be the best choice with respect to stability, permeability and selectivity. For a better understanding of the gas separation taking place according to the governing mechanism, selective surface flow, the sorption and diffusion coefficients were investigated more closely. This is reported in the current paper for the gases Cl 2 , HCl, R22 (CHF 2 Cl), He, H 2 , N 2 , CO, O 2 , Xe, SF 6 and CO 2 . Temperature and pressure range focused on were 1–4 bar and 30–45 °C, respectively, as these ranges were judged to be most interesting with respect to possible changes in the transport through the Pt-C10 surface modified glass membrane. The degree of selective surface flow, SSF, relative to the Knudsen flow is also discussed in this work. When plotting the sorption coefficient versus degree of SSF, there seems to be two distinct patterns: The Cl 2 , HCl and R22 (all containing chlorine and have high critical temperatures) are described by exceptionally high sorption coefficients, while the other gases are best described by an exponential fit. The heat of adsorption for Cl 2 and HCl was found to be comparable to the heat of condensation at the same pressure. It was assumed that the adsorption of these gases corresponds to the proposed “sliding liquid layer” flow described in the literature, while the exponential behaviour of the other gases correspond to the “site to site hopping” or 2D gas flow.

To achieve amorphous silicon nitride (a-SiN x ) thin films with minimal incorporation of impurities such as carbon and hydrogen, a novel liquid source precursor, tris(diethylamino)chlorosilane (TDEACS), was developed. TDEACS and ammonia (NH 3 ) were used to produce a-SiN x films by low pressure chemical vapor deposition in a hot wall tubular reactor. The growth kinetics was investigated as a function of total pressure, NH 3 /TDEACS flow ratio, and deposition temperature. The film compositions and topography were characterized by X-ray photoelectron spectroscopy, Auger depth profile, Fourier transform infrared spectroscopy, elastic recoil detection, and atomic force microscopy, respectively. The growth rate of the films follows an Arrhenius behavior with apparent activation energy of 182.6 kJ·mol −1 between 600 and 750 °C. At NH 3 /TDEACS flow rate ratios below 4, carbon-containing a-SiN x films were obtained while all films were stoichiometric with a N/Si atomic ratio 1.30–1.32 as the ratios beyond 6. Both carbon and hydrogen contents of the prepared a-SiN x films were markedly lower than those prepared from other organic precursors previously reported. The surface topography of the films is smooth and uniform with a root mean square roughness value of 0.53 nm.

In this thesis oxidative coupling of H-phosphonate and H phosphonothioate diesters with different alcohols and amines are presented. Since the reactions with alcohols previously have been particularly unfavourable due to competing side reactions, a modified protocol leading to high coupling yields of structurally diverse hydroxylic components was developed. The phosphorylation reaction was studied using 31P NMR spectroscopy and for the first time the previously only postulated reactive intermediate involved in these reactions was observed. The use of iodine in combination with a bulky chlorosilane in pyridine was found to have a profound effect on both the suppression of side reactions and the rate of the oxidative couplings, and led to a clean formation of phosphorylated products in high yields. This synthetic protocol was then extended to include coupling reactions with bis-functional reagents containing hexamethylene linkers to provide handles for derivatisations of oligonucleotides.A synthetic protocol consisting of the stereospecific oxidative coupling of amines with H-phosphonate diesters to produce phosphoroamidates was designed in such a way that it permitted control of the stereochemical outcome of the reactions.Based on a silylation-mediated reaction utilising phenyl H phosphonothioate monoester as a thiophosphonyl transferring agent, a method was developed and used for the preparation of H-phosphonothioate building blocks for the synthesis of DNA analogues.

Filamentary crystals and nanotubes of 3C-SiC containing α-SiC are prepared. The nanostructures of SiC are synthesized from a mixture of hydrocarbons, chlorosilane and hydrogen in the presence of iron (Fe(CO)5) at 1250° C. The average nanofilament diameter is 30 nm. The nanotube diameter ranges from 10 to 200 nm.

In an attempt to synthesize amorphous silicon nitride (a-SiN x ) thin films with minimal incoporation of impurities, a novel liquid precursor, tris(diethylamino)chlorosilane (TDEACS), was synthesized and proven to be an ideal candidate as a silicon and nitrogen source for depositing of high-quality a-SiN x thin films. a-SiN x films with low carbon and hydrogen contents were prepared from a TDEACS–NH 3 –N 2 system by the LPCVD technique. The films were characterized by X-ray photoelectron spectroscopy, Auger depth profile, Fourier transform infrared spectroscopy, elastic recoil detection, and atomic force microscopy, respectively. Carbide-containing a-SiN x films were obtained at lower NH 3 /TDEACS ratios while all deposits were essentially stoichiometric at higher NH 3 /TDEACS ratios. Both carbon and hydrogen contents of the as-prepared a-SiN x films were markedly lower than of those prepared from other organic precursors previously reported. The surface topography of the as-prepared film was smooth and uniform with a root-mean-square roughness of 0.53 nm.

As in previous papers in this series, we created membranes for solubility-based gas separations by reacting the surfaces of microporous alumina substrates with alkylchlorosilanes. In this paper, we explored our ability to rationally modify the permselectivity properties of these membranes through the control of several synthesis variables. In particular, we studied three different hydration states of the alumina surface (dehydrated, normal, and superhydrated), two different degrees of chlorosilane functionality (mono and tri), and two different sizes of alkyl group (methyl and octadecyl). We measured the permeability of the hybrid membranes to propane and nitrogen gases to characterize their separation properties; we also carried out X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) experiments to characterize the amount and nature of organic surface coverage. Our results showed significant correlations of permeation properties with all of the synthesis variables. Dehydration of the alumina surface before trichlorosilane treatment resulted in a lower organic surface coverage and a lower propane/nitrogen selectivity; superhydration resulted in the formation of a dense organic surface layer with a large number of macroscopic defects that virtually eliminated selectivity. Under normal hydration conditions, the octadecyltrichlorosilane yielded a far more selective membrane than the methyltrichlorosilane. Finally, the monochlorosilane reagents produced no significant organic surface coverage, based on both XPS and gas permeation analyses. We discuss our results in the context of previous work on (1) self-assembled monolayers on nonporous substrates and (2) the design of solubility-selective membranes.