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The surface modification of hydrophobicity on silica is important in industrial applications. Silane adhesives, such as chlorosilane, hexamethyldisilazane, and polydimethylsiloxane, are widely used...

A new type of model branched polymer, asymmetric H-shaped polybutadienes, consisting of central crossbars having various combinations of short and long arms attached to the ends of the crossbars, was synthesized using living anionic polymerization and chlorosilane linking chemistry. The linking agent 4-(dichloromethylsilyl)diphenylethylene provides selective reactivity to attach short or long arms on one side or both sides as desired. The samples were characterized thoroughly by size exclusion chromatography with light scattering detection (SEC-LS) and found to exhibit controlled molecular weights, as well as narrow polydispersity indices (PDIs of 1.01–1.06). Temperature gradient interaction chromatography, a method with far superior resolution as compared to SEC, also shows that these materials are well-defined, with minimal and identifiable impurities.

Herein we describe a nickel-catalyzed remote hydrosilylation of unconjugated enones with bulky triphenylsilane. A range of Z-silyl enol ethers are obtained as major isomers due to the process of nickel triggered alkene isomerization. Notably, some specific alkyl silyl enol ethers can be prepared from this protocol, which are not easily accessed by the traditional strategy using a strong base and chlorosilane. This reaction features 100% atom economy, simple reaction conditions, and good yields.

Improving the photoelectric conversion efficiency and long-term stability are two substantial goals for the research work of perovskite photovoltaics, which can be realized through appropriate surf...

Silica aerogel (SA) particle was synthesized and characterized. The effects of silica content in silicic acid solution and molar ratio of trimethyl chlorosilane (TMCS)/pore water on silica aerogel physical characteristics such as surface area, pore volume, apparent density, and porosity were investigated. We observed that when the silica content increased from 4 to 7% of weight (wt%), the silica aerogel surface area increased from 628.5 m2/g to 914.4 m2/g and thereafter (>9%). When the molar ratio of TMCS/pore water increased from 0.1–0.4, the silica aerogel’s surface area increased from 816.8 m2/g to 924.1 m2/g. The highest silica aerogel surface area of 924.1 m2/g and porosity of 96.4% were achieved with a silica content in silicic acid of 7.011 wt% and TMCS/pore water of 0.4. Finally, silicon aerogel particles applied to water-based paint to improve the thermal insulation was about 1.2 °C with surrounding ambient temperature of 45 °C.

The reaction of 2-t-Bu-germabenzenylpotassium with Me2(t-Bu)SiCl (TBDMSCl) resulted in the coupling among two TBDMS-substituted germabenzenes and the germabenzenylpotassium. The structure of the pr...

Nano-silica particles were prepared using chlorosilane residual liquid as raw materials in an inverse microemulsion system formed by three different surfactants (TX-100, CTAB, SDS) with n-hexanol, cyclohexane, and ammonia. The phase behavior of inverse microemulsions and the preparation of nano-silica were investigated. The results showed that the system composed of non-ionic surfactant TX-100 had a larger inverse microemulsion region than other two system and was more suitable for the preparation of nano-silica. The prepared nano-silica had uniform sphericity and good dispersibility, the average particle diameter of 31 nm, and the variance of 1 nm. XRD, FT-IR, N2 adsorption/desorption experiments and TG-DSC analysis were used to characterize the prepared nano-silica. The results showed that the prepared nano-silica was amorphous mesoporous silica with a BET specific surface area of 472.5 m2/g. They have a good thermal stability, and the phase structure and main chemical functional groups of nano-silica would not change after calcination at 600 °C, but the nano-silica would undergo a phase change at 1135 °C, which changed from amorphous to crystalline. The new technology not only broadened the source of preparation of nano-silica materials, but also provided new ideas for the treatment of chlorosilane residual liquid and the sustainable development of polysilicon industry.

The phase diagrams of the liquid systems RnSi(OR’)4−n-Me2CO-H2O and RnSiCl4−n-Me2CO-H2O, where R = Me, Ph; R’ = Me, Et; n = 0–2, were compared. Mathematical modeling of the phase equilibrium in these systems was performed on the basis of the UNIFAC and NRTL equations. The heterogeneous regions, conodes of phase equilibrium, and compositions of the coexisting phases are determined. A satisfactory description of the experimental data by the parameters of the models of phase equilibrium obtained on the basis of the NRTL equations is shown for the phase diagrams of the MeSi(OEt)3/Si(OEt)4-Me2CO-H2O systems. The heterophase character due to the mutual insolubility of the monomers and water is common for both systems. The heterogeneous region of the RnSi(OR’)4−n-Me2CO-H2O system is smaller than that of RnSiCl4−n-Me2CO-H2O (calculation by the UNIFAC method). At the same acetone concentration, the water concentration in the organic phases of the “alkoxy” systems is higher than that in the “chlorosilane” systems. The replacement of acetone with ethanol and AcOH leads to a sharp reduction of the heterogeneous region.

We report a new method for the synthesis of acylphosphine oxides by the direct coupling of hydrogen phosphine oxides and acyl chlorides mediated by chlorosilanes. This new protocol is greener and safer, because it precludes the generation of volatile haloalkanes and the use of oxidants employed in the conventional methods. Moreover, moisture-unstable acylphosphine oxides that are difficult to prepare via the conventional methods can be generated using this new method.

Monosubstituted B-chloro(organo)silylmethyl-o-carboranes have been synthesized for the first time by the reaction of o-carborane with chloromethyl(organo)chlorosilanes in the presence of catalytic amount of aluminum chloride. The reaction proceeds at temperature of 200–250°C under a pressure of 22–25 atm. A decrease in the number of chlorine atoms in the molecule of chloromethyl(organo)chlorosilane decreases the yield of the target product.

The organocatalytic controlled/living ring-opening polymerization (ROP) of cyclotrisiloxanes such as hexamethylcyclotrisiloxane (D3) and 1,3,5-trimethyl-1,3,5-trivinylcyclotrisiloxane (V3) using silanol initiators and guanidine catalysts produced various asymmetric linear poly(dimethylsiloxane) (PDMS) and poly[methyl(vinyl)siloxane] (PMVS) compounds with controlled number-average molar mass (Mn), narrow molar-mass dispersity (ĐM), and well-defined terminal structures. An extensive range of solvents and catalysts were tested in order to optimize the conditions for the ROP of D3 and V3 as well as to minimize undesired side-reactions, particularly the condensation of two Si–OH groups. 1,3-Trimethylene-2-n-propylguanidine (TMnPG) and 1,3-trimethylene-2-ethylguanidine (TMEG) were identified as the most appropriate catalysts for the ROP of D3 and V3. Asymmetric linear polysiloxanes that contain either a functional group on one terminus, i.e., hemitelechelic polysiloxanes, or two different functional groups on each terminus, i.e., heterotelechelic polysiloxanes, were conveniently obtained from choosing a suitable combination of a functionalized silanol initiator and a functionalized chlorosilane end-capping agent. The controlled synthesis of a PDMS/PMVS diblock copolymer was also achieved by consecutive copolymerizations of D3 and V3. These polymerizations are considered to proceed via the initiator/chain-end activation mechanism, and intensive removal of water from the starting materials is necessary to control the polymerizations.

The dinuclear (thio)(silyl)carbene and (seleno)(silyl)carbene gold(i) complexes 1 and 2 were obtained from the reaction of two equivalents of AuCl(SMe2) with the stable bis(methylene)-λ4-chalcogenanes 3 and 4, respectively. The reaction proceeds under elimination of the chlorosilane moiety of 3 and 4. Complexes 1 and 2 were characterized by spectroscopic and X-ray diffraction (XRD) analyses. The 13C NMR signals for the carbene centers of 1 (309 ppm) and 2 (345 ppm) are by more than 150 ppm downfield shifted relative to those for other known (NHC)AuCl complexes. These results indicate that (chalcogeno)(silyl)carbenes, like (amino)(silyl)carbenes, belong to the push-spectator family of carbenes.

Various borohydrides were found to catalyze the redistribution reaction of hydrosilane and chlorosilane in different solvents to produce hydrochlorosilanes efficiently and facilely. The redistribution reaction was affected by solvent and catalyst. The substrate scope was investigated in HMPA with LiBH4 as catalyst. A possible mechanism was proposed to explain the redistribution process.

The zinc-promoted silylation method is of great importance to synthesize high-performance silicon-containing arylacetylene (PSA) resins in the industry. However, it is difficult to eliminate the accompanied by-product of terminal alkenes due to the lack of mechanistic understanding of the silylation. The initiation of zinc-promoted silylation is facilitated by the interaction between zinc and phenylacetylene. Our DFT calculations indicated that the intermolecular hydrogen transfer of phenylacetylene follows an ionic pathway, which generates a phenylacetylene anion and the corresponding alkene moieties on the zinc surface. The styrene by-product is observed in this stage, with its alkene moieties desorbing as radicals into the solvent under the high reaction temperature. Three possible intermediates of surface phenylacetylene anions were proposed including PhC[triple bond, length as m-dash]C-Zn, PhC[triple bond, length as m-dash]CZnCl, and (PhC[triple bond, length as m-dash]C)2Zn. These carbanion-zinc intermediates undergo an SN2 reaction with Me3SiCl to afford the alkynylsilane on the zinc surface, which is calculated to be the rate-determining step for the zinc-promoted silylation reaction.

This present study was conducted to determine the aptitude of hydrophobic silane coating in corrosion resistance of AISI 304 stainless steel substrate at the nanoscale. Three newly developed hydrophobic silane-based compounds of compositions, namely [tris(trimethylsiloxy)silyethyl]dimethylchlorosilane (alkyl); tridecafloro-1,1,2,2-tetrahydrooctyltrichlorosilane (FOTS); and henicosyl-1,1,2,2-tetrahydrododecyltricholrosilane (FDDTS), were used as precursors to coat AISI 304 stainless steel surfaces. Prior to deposition, the substrate surfaces were pretreated with plasma oxide via a multi-step treatment to serve as adhesion. The plasma oxide and the silane precursors were deposited by using a hybrid atomic layer deposition and chemical vapor deposition process. The structural, chemical and electrochemical stabilities were investigated using SEM, AFM, XRD, ATR-FTIR, potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). The results showed that the microstructures and morphology of the coated samples were similar, due to the chlorosilane functionalization. The FTIR indicated complete hydrolysis at the nanoscale while the polarization results showed that nano-coating can hamper the corrosion propagation mechanisms. Furthermore, the EIS results revealed that all the precursors acted as a barrier to AISI 304 dissolution into the electrolyte. The electrochemical effect was observed in the microstructural transformation of the coatings. Although all the precursors were shown to have been effective at few nanoscales, the stability of the FDDTS showed to have superseded that of alkyl and FOTS.

Superhydrophobic (SH) silica (SiO2) nanoparticles (NPs) were successfully synthesized through a simple and facile technique. The effect of chlorosilane isomers was investigated by the grafting of butyltrichlorosilane (C4But) and dichloro (3-chloropropyl) methylsilane (C4Di) on superhydrophilic SiO2 NPs. The SEM results displayed that the particle size of C4Di modified SiO2 (C4Di-SiO2) NPs was larger than C4But modified SiO2 (C4But-SiO2). This can be due to the steric effect of the methyl group on the C4Di segment. The wetting analysis revealed that C4Di-SiO2 cannot reach SH criteria as it showed a water contact angle (WCA) of 149° and a sliding angle (SA) over 10°, while C4But-SiO2 showed a SH surface with a WCA of 159° and SA of 2°. Interestingly, the modified SiO2 NPs created a transparent film on the glass substrate which is a key opportunity for self-cleaning application.

The interaction of chlorosilanes and the silicon surface is an important part of reaction processes, such as hydrochlorination and chemical vapor deposition, involved in the production of high purity silicon. We used plane-wave based density functional theory (DFT) to investigate periodic slabs of the Si(100)-c(4 × 2) surface for adsorption of H2, HCl, SiCl2, dichlorosilane (SiH2Cl2 or DCS), trichlorosilane (SiHCl3 or TCS) and silicon tetrachloride (SiCl4 or STC). The effects of surface coverage, molecule orientation, adsorption site and multiple molecule adsorption were studied. All the molecules could undergo dissociative chemisorption in the right orientation and site placement, with HCl and SiCl2 possessing the strongest binding energies. The H2 molecule preferred lower coverage, the HCl molecule was not much affected by coverage while the SiCl2 molecule strongly preferred higher coverage and the STC molecule was affected negatively by both too high or low coverage. The elementary steps leading to transfer of surface crystal silicon atoms to gas phase molecules as part of the chlorination or hydrochlorination process were then looked at through reaction pathway analysis. The formation of SiCl2 from a surface dimer Si atom was found to prefer an intradimer route with a reaction barrier of 3.62 eV (83.48 kcal/mol), going down to 3.10 eV (71.49 kcal/mol) after removal of the first surface Si atom. The subsequent formation of TCS from this SiCl2 was found to have reaction barrier of 1.07 eV (24.68 kcal/mol). STC could also be formed from this SiCl2 molecule with a reaction barrier of 2.86 eV (65.95 kcal/mol).

This article demonstrates an effective in-situ method for the preparation of ethylene-propylene rubber/silica composites (EPR/SiO2) via continuous process with two stages: in the first stage, functional olefin monomers containing trichlorosilane group (CSO) are designed and the terpolymerization of ethylene/propylene/CSO catalyzed by metallocene catalyst is implemented; in the second stage, by dispersing the SiO2 directly into the unterminated polymerization solution, the copolymer chains are anchored to the SiO2 particles via the reaction between the hydroxyl on SiO2 surface and pendant chlorosilane groups on the EPR chains. The CSO content in the copolymers was tailored in relatively wide range from 0.71 mol% to 4.68 mol%, which provided various chlorosilane groups for the anchoring reaction on SiO2 surface. Thus a series of EPR/SiO2 chemical composites (with the SiO2 content of 13 wt% ∼ 85 wt%) were prepared via the highly efficient elimination reaction between Si-Cl and Si-OH groups. The dispersing morphology and stability of SiO2 in EPR/SiO2 composites were compared with that of the physically blended EPR/SiO2 systems. Owing to the covalent bonding between polymer chains and SiO2 particles, the problem of compatibility between the rubber and the filler was fundamentally solved.

A nickel-catalyzed reductive cross-coupling of redox-active N-hydroxyphthalimide (NHP) esters and iodoarenes for the synthesis of α-aryl nitriles is described. The NHP ester substrate is derived from cyanoacetic acid, which allows for a modular synthesis of substituted α-aryl nitriles, an important scaffold in pharmaceutical sciences. Mechanistic studies reveal that decarboxylation of the NHP ester to the reactive radical intermediate is accomplished by a combination of a chlorosilane additive and Zn dust. The reaction exhibits a broad scope as many functional groups are compatible under the reaction conditions, including complex highly functionalized medicinal agents.

International audience; Linear and non-linear copolymers of the PB-b-PI sequence [PB: polybutadiene of high 1,4-microstructure (∼92%) and PI: polyisoprene of high 3,4-microstructure (∼55–60%)] and their corresponding miktoarm star copolymers of the PB(PI3,4)2 and PB(PI3,4)3 type were synthesized by combining anionic polymerization and selective chlorosilane chemistry. Molecular characteristics, thermal properties and structure/properties relationship are reported for the specific copolymers and especially the self-assembly is of major importance and interest due to the nature of the blocks. The identical electron densities between the two polydienes led to impossible morphological characterization through small angle X-ray scattering (SAXS) and only transmission electron microscopy results verify the adopted morphology for each copolymer, justifying the assumption that the segment–segment interaction parameter between the two polydienes of high 1,4-microstructure (∼92%) for the PB and ∼55–60% 3,4-microstructure for the PI is well above zero. The consistency of the bulk morphology results of this study compared with those of the extensively studied system of the PS(PI)n=1,2,3 type (PS: polystyrene), were unexpectedly coherent. High chain flexibility provided by the two polydiene segments, leads to promising properties unattainable from corresponding thermoplastic triblock copolymers of these polydienes with PS (PS-b-PI-b-PS, PS-b-PB-b-PS), especially for rheological studies.

The versatile reactivities of disilenides and digermenide, heavier analogues of vinyl anions, have significantly expanded the pool of silicon and germanium compounds with various unexpected structural motifs in the past two decades. We now report the synthesis and isolation of a cyclic heteronuclear vinyl anion analogue with a Si=Ge bond, potassium silagermenide as stable thf‐solvate and 18‐c‐6 solvate by the KC8 reduction of germylene or digermene precursors. Its suitability as synthon for the synthesis of functional silagermenes is proven by the reactions with chlorosilane and chlorophospane to yield the corresponding silyl‐ and phosphanyl‐silagermenes. X‐ray crystallographic analysis, UV/Vis spectroscopy and DFT calculations revealed a significant degree of π‐conjugation between N=C and Si=Ge double bonds in the title compound., The first heteronuclear vinyl anion consisting of two heavier Group 14 elements, silagermenide 3⋅K(18‐c‐6), is readily accessible by KC8 reduction of a NHC‐stabilized germylene or the corresponding NHC‐free digermene. Its applicability as synthon for the synthesis of unprecedented functional silagermenes 4 a,b and evidence for significant π‐conjugation between the N=C and Si=Ge are also reported.

One-electron oxidation capability with Lewis acidity of oxovanadium(v) compounds allows oxidative carbon–carbon bond formation. A combination of boron enolate and silyl enol ether is effective for the selective cross-oxidative coupling. Ligand-coupling reactions, which are coupling reactions of organic substituents on main-group organometallic compounds, are also induced by oxidation with oxovanadium(v) compounds. As main-group metals, Al, Zn, B, etc., can be used in these reactions. Low-valent vanadiums or titaniums contribute to reductive coupling reactions as a catalyst, as exemplified by pinacol coupling reaction, which requires the presence of chlorosilane and co-reductant, zinc. Use of an heterobimetallic catalyst consisted of vanadium and titanium permits the selective cross-coupling between aryl and aliphatic aldehydes.

In this study, mesoporous silica nanoparticles (MSNs) were successfully prepared in two steps using chlorosilane residue. First, chlorosilane residue was subjected to alcoholysis with n-propanol to synthesize tetrapropoxysilane (TPOS), followed by the synthesis of MSNs using TPOS as silicon source. Alcoholysis experiment was designed and optimized using orthogonal experimental method. In addition, effects of four factors (i.e., molar ratio of n-propanol to chlorosilane residue; feed rate of n-propanol; reaction temperature; and molar ratio of n-hexane to chlorosilane residue) on the yield of TPOS were investigated. The optimum alcoholysis conditions were determined. Yield of TPOS was 56% under the optimum alcoholysis conditions. Results obtained from single factor analysis of variance revealed that molar ratio of n-propanol to chlorosilane residue was the most significant factor affecting TPOS yield. Next, a series of spherical MSNs with dendritic structure and irregular mesoporous/microporous silica nanoparticles with non-dendritic structure were successfully synthesized via precise regulation of various experimental parameters in emulsion systems. In this regard, the adjustment of n-hexanol/1,3,5-triisopropylbenzene (TIPB) molar ratio or n-octane/n-hexanol/TIPB molar ratio was found to be effective for achieving controllable regulation of morphology (spherical or irregular); structure (dendritic or non-dendritic); pore size (mesoporous (4.6–9.2 nm) or microporous (1.6–1.7 nm)); and particle diameter (60–134 nm) of silica nanoparticles. However, the adjustment of n-octane/TIPB molar ratio marginally affected spherical morphology, dendritic structure, and pore size (4.0–4.6 nm) of synthesized MSNs, with considerable effect on particle diameter (61–151 nm). In addition, as-synthesized MSNs exhibited large specific surface area (708–857 m2/g) and large pore volume (1.5–3.6 cm3/g).

The surfaces of indium tin oxide coated glass substrates were functionalized with a surface grafted, covalently bound photoinitiator. These surface functionalized substrates were used to assemble liquid crystal (LC) test cells. The LC test cells obtained were filled with reactive mixtures of a nematic LC doped with reactive mesogens (acrylate monomers). First, the anchoring properties of the surface-grafted photoinitiator were investigated. Next, the test cells were exposed to UV light in order to in-situ generates a surface grafted polymer network LC with enhanced electro-optic responses. The surface grafted photoinitiator (benozophenonesilane) had two functional groups separated by an aliphatic spacer: Benozophenonesilane possess one chlorosilane functional group for covalent attachment to surface hydroxyl groups (present at the substrate surface). The second functional group was a benzophenone functional group, suitable to initiate photopolymerization of acrylate monomers. As host LC, the nematic LC E7 was used. Samples doped with two different reactive mesogens (RM257 and BAB6) were investigated. The electro-optic response properties of samples were investigated before and after exposure to UV light. As reference samples, a conventional polymer network LC was generated with a dissolved photoinitiator and investigated in test cells assembled with non-surface functionalized substrates. In contrast to a conventional polymer network LC, the polymer network was surface grafted to the substrates if benzophenone silane was used as photoinitiators (where these molecules acted as crosslinker between polymer and substrate). It was clearly shown that test cells with benzophenone silane coated surfaces were suitable to generate a polymer network LC: The presence of a surface grafted polymer network led to desirably fast electro-optic responses.

The hydrochlorination reaction used in polysilicon production is often catalyzed through copper-based materials which have been found to form the Cu3Si intermetallic under reaction conditions. The ...

The fluidized bed reactor with multiple tubular and segmented heat transfer was employed to study the effects of mass flow rate of MeCl and reaction pressure on the rate of MeCl conversion and the methyl chlorosilane yield at 300 degrees C. The rate of MeCl conversion and the yield of Me2SiCl2 were not always increased with increasing mass flow rate of MeCl at constant reaction pressure under particular operating conditions. At constant mass flow rate, the rate of MeCl conversion and the yield of Me2SiCl2 decreased first, and then increased with increasing reaction pressure. Therefore, for the fluidized bed reaction system, a synergism between the MeCl mass flow and reaction pressure in effecting the MeCl conversion rate and the yield of Me2SiCl2 was obsd. The reaction pressure for optimum yield of Me2SiCl2 was 0.30 MPa and MeCl mass flow rate was 4.5 kg/h.

In this study, molecular layer deposition (MLD) was used to deposit ultrathin films of methylene-bridged silicon oxycarbide (SiOC) using bis(trichlorosilyl)methane and water as precursors at room temperature. By utilizing bifunctional trichlorosilane precursors, films of SiOC can be deposited in a layer-by-layer manner, wherein a water co-reactant circumvents the need for plasma, high temperatures, or highly oxidizing precursors. In this manner, films could be grown without the degradation commonly seen in other SiOC deposition methods. Saturation behavior for both precursors was confirmed for the MLD process, and a constant growth rate of 0.5 ± 0.1 Å/cycle was determined. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy were used to verify the reaction between precursors and to gain insight into the final film composition. Unlike most MLD films, which grow polymers in a linear fashion, XPS analysis indicates that neighboring silanol groups within the films tend to condense, forming a highly cross-linked network structure, whereby, on average, two-thirds of silanol groups undergo a condensation reaction. Further indication of cross-linking is seen by XPS during in situ annealing, which shows exceptional temperature stability of the film up to 600 °C in vacuum, in contrast to linear SiOC films, which are known to degrade below this temperature. The films also exhibit high chemical stability against acids, bases, and solvents. A film density of 1.4 g/cm

New aminosilanes with hydrolysable Si-N bond(s) were prepared by the amination of chlorosilanes and used as hydrophobic modifiers of SiO2 surface. The aminosilanes are rather stable towards hydrolysis in air compared to their chlorosilane analogs. The modified SiO2 was applied as a gate insulator of an organic thin-film transistor with a vapor-deposited film of pentacene as the active material. The transistor with the aminosilane-modified SiO2 showed two- to threefold higher hole mobility than the device with bare SiO2.