Diphenyl Silane Research Articles

Preparation and properties of visible light-cured strippable film for radioactive decontamination

In this research, solutions of styrene-butadiene-styrene block copolymer (SBS) in 2-ethoxyethyl methacrylate (EOEMA) were used to prepare strippable films via rapid visible-light curing, where the mixture of camphorquinone (CQ), diphenylsilane (DPS) and diphenyliodonium hexafluorophosphate (Iod) was employed as the photoinitiating system, LED@405 nm, sunlight or household LED panel light as the light source and no any solvent was involved. The double bond conversion for pure EOEMA under LED@405 nm was firstly monitored by real-time FTIR and it reached 72% within 300 s. The rapid-curing of SBS/EOEMA solutions were systematically investigated and it was found that the solution with 16 wt% SBS became completely dried at the presence of 2.16 mol% crosslinker and 3.6 wt% photoinitiating system after 240 s irradiation under LED@405 nm. The tensile strength, elongation at break and glass transition temperature of the resultant strippable film were determined to be about 4.4 ± 0.5 MPa, 130 ± 11.2% and 6.9 °C, respectively, by mechanical properties testing and DSC measurements. Also, the decontamination efficiencies (DE) of household LED panel light/sunlight cured-strippable film for uranium nitrate on stainless steel, glass, and ceramic surface were evaluated to be higher than 90%. These results indicate that this rapid-curing strippable films would be a good candidate material for large-scale radioactive decontamination.

Transition-metal- and solvent-free regioselective hydrosilylation of alkenes and allenes enabled by catalytic sodiumtert-butoxide

An efficient and sustainable method involving alkali metal Lewis base NaOtBu as a catalyst and diphenyl silane as a silane reagent for the hydrosilylation of vinylarenes, aliphatic alkenes and allenes with high regioselectivity has been developed.

Synthesis of ultra-high molecular weight poly(methyl methacrylate) with hydrosilane as initiator

Hydrosilanes, including diethylsilane (DES), triethylsilane (TES), phenylsilane (PSH), and diphenylsilane (DPS), have in the present study been used as initiators for the preparation of poly(methyl methacrylate) (PMMA) in the presence of Pd nanoparticles (Pd NPs). DPS initiated the polymerization of MMA in the production of PMMA, with a number average molecular weight ( M n ) of 2.00×10 6 Da and a dispersity (PDI) of 1.81 in the presence of 18.9 ppm of Pd NPs. The kinetic of the polymerization was investigated and the reaction orders, with regard to the MMA, DPS, and Pd NPs, were calculated as 0.85, 0.58, and 0.80, respectively. The molecular weight of the PMMA was measured using gel permeation chromatography (GPC) and the structure was characterized using proton nuclear magnetic resonance ( 1 H NMR). The transmission electron microscopy (TEM) and electron spin resonance (ESR) results revealed that the polymerization took place at the surface of the Pd NPs through a radical mechanism. • A novel route for preparing ultra-high molecular weight poly(methyl methacrylate) with hydrosilane as initiator had been proposed. • An ultrahigh molecular weight poly(methyl methacrylate) with number-average molecular weight of 2.00×10 6 Da was synthesized at mild conditions. • Kinetic of the polymerization of MMA initiated by DPS was investigated. • The mechanism study reveals that the polymerization was conducted via a radical mechanism.

Trifluoromethanesulfonamide vs. Non-Fluorinated Sulfonamides in Oxidative Sulfamidation of the C=C Bond: An In Silico Study.

A theoretical analysis of the reaction of oxidative sulfamidation of several alkenes was performed in order to explain the various experimental observations and different reactivity of triflamide and non-fluorinated sulfonamides. Transformations occurring in the system alkene–sulfonamide in the presence of oxidative system (ButOCl + NaI) were analyzed at the MP2/DGDZVP//B3LYP/DGDZVP level of theory using the IEF-PCM method for taking into account the solvent acetonitrile (MeCN) effect. As the model substrates, styrene, trimethyl(vinyl)silane, dimethyl(divinyl)silane and diphenyl(divinyl)silane were chosen and mesylamide, triflamide, tosylamide and p-nosylamide were taken as the reagents. ButOI generated from ButOCl and NaI reacts with sulfonamides to give N-iodinated sulfonamides RSO2NHI and RSO2NI2 as active intermediates, the iodinating activity of the latter being notably higher. The analysis allowed to answer such challenging questions as different reactivity of nonfluorinated sulfonamides leading to aziridination and of triflamide resulting in the formation the main products of bis-triflamidation, or different regioselectivity of halogenation of styrene and trimethyl(vinyl)silane caused by a linear intermediate iodonium cation in the former case and a cyclic one in the latter.

High Performance Redox Initiating Systems Based on the Interaction of Silane with Metal Complexes: A Unique Platform for the Preparation of Composites.

Currently, Redox Initiating Systems (RISs) of Free Radical Polymerization (FRP) are mainly based on the interaction of aromatic amines with peroxides (e.g., dibenzoyl peroxide (BPO)) that can be both toxic and unstable. In the present work, we aim to replace these hazardous substances in new RIS that can be peroxide-free and amine-free. Our redox two components (2K) initiating system is based on diphenylsilane (DPS) as reducing agent combined with different metal complexes (Mn(acac)2, Cu(AAEMA)2 or Fe(acac)3) as oxidizing agents. For the new proposed RIS, an excellent reactivity is found for the polymerization of benchmark methacrylate monomers under mild conditions (redox polymerization done under air and at room temperature); remarkably, it is also possible to finely control the gel time. Different techniques (optical pyrometry, Real-Time FTIR spectroscopy, Cyclic Voltammetry and Electron Spin Resonance (ESR)) were used to follow the polymerization processes but also to shed some light on the new redox chemical mechanisms.

Space‐Confined Atomic Clusters Catalyze Superassembly of Silicon Nanodots within Carbon Frameworks for Use in Lithium‐Ion Batteries

AbstractIncorporating nanoscale Si into a carbon matrix with high dispersity is desirable for the preparation of lithium‐ion batteries (LIBs) but remains challenging. A space‐confined catalytic strategy is proposed for direct superassembly of Si nanodots within a carbon (Si NDs⊂C) framework by copyrolysis of triphenyltin hydride (TPT) and diphenylsilane (DPS), where Sn atomic clusters created from TPT pyrolysis serve as the catalyst for DPS pyrolysis and Si catalytic growth. The use of Sn atomic cluster catalysts alters the reaction pathway to avoid SiC generation and enable formation of Si NDs with reduced dimensions. A typical Si NDs⊂C framework demonstrates a remarkable comprehensive performance comparable to other Si‐based high‐performance half LIBs, and higher energy densities compared to commercial full LIBs, as a consequence of the high dispersity of Si NDs with low lithiation stress. Supported by mechanic simulations, this study paves the way for construction of Si/C composites suitable for applications in future energy technologies.

Space-Confined Atomic Clusters Catalyze Superassembly of Silicon Nanodots within Carbon Frameworks for Use in Lithium-Ion Batteries.

Incorporating nanoscale Si into a carbon matrix with high dispersity is desirable for the preparation of lithium-ion batteries (LIBs) but remains challenging. A space-confined catalytic strategy is proposed for direct superassembly of Si nanodots within a carbon (Si NDs⊂C) framework by copyrolysis of triphenyltin hydride (TPT) and diphenylsilane (DPS), where Sn atomic clusters created from TPT pyrolysis serve as the catalyst for DPS pyrolysis and Si catalytic growth. The use of Sn atomic cluster catalysts alters the reaction pathway to avoid SiC generation and enable formation of Si NDs with reduced dimensions. A typical Si NDs⊂C framework demonstrates a remarkable comprehensive performance comparable to other Si-based high-performance half LIBs, and higher energy densities compared to commercial full LIBs, as a consequence of the high dispersity of Si NDs with low lithiation stress. Supported by mechanic simulations, this study paves the way for construction of Si/C composites suitable for applications in future energy technologies.

Silane Based Redox Initiating Systems: Toward a Safer Amine-Free, Peroxide-Free, and Metal-Free Approach

Room temperature redox initiated free radical polymerization (RFRP) has always attracted high attention in the field of materials due to its advantages of energy saving, high efficiency, and easy operation. However, the current redox initiating systems are based on toxic aromatic amines and hazardous peroxides (e.g., dibenzoylperoxide). In the present paper, the redox two component (2K) initiating performances of silanes (as reducing agents) in combination with a highly stable iodonium salt (as oxidizing agent) were studied for the first time under mild conditions (RT, under air). Optical pyrometry measurements and DSC investigation results showed that the diphenylsilane (DPS) exhibited a unique initiating property for several (meth)acrylate monomers. Remarkably, thermal postcuring (B-stage) is also possible using this system. Based on electron spin resonance (ESR) experiments, the initiating chemical mechanisms of RFRP are established. Importantly, the new proposed initiating systems can be used for the preparation of tack-free glass fibers and carbon fibers composites at room temperature.

Nghiên cứu chế tạo nhựa epoxy biến tính bằng hợp chất silan dùng trong sản xuất keo dán hàng không chịu nhiệt

This paper presents some results of the study on modifying epoxy resin with dichloro diphenyl silane and developing heat-resistant adhesive from this modified resin. Some important specifications such as the tensile strength and the heat resistance of the adhesive based on modified epoxy and curing agent of low-molecular polyamide resin have been tested. The tested results have shown that the obtained adhesives began to decompose at 300°C, the tensile strength is 20.5 MPa. The obtained adhesives can be used as aviation heat-resistant adhesive, replacing some imported adhesives.

Evaluating and Modeling the Internal Diffusion Behaviors of Microencapsulated Rejuvenator in Aged Bitumen by FTIR-ATR Tests.

Microencapsulated rejuvenator has been attracted much attention for self-healing bitumen. The diffusion coefficient is one of the key parameters to estimate the feasibility of rejuvenator to age bitumen. The objective of this research was to evaluate diffusion behaviors of microencapsulated rejuvenator in aged bitumen by a FTIR-ATR method. Various microcapsule samples were mixed in bitumen to form thin films. The core material of microcapsules used as rejuvenator was diphenylsilane (DPS), its fairly specific absorption band at 843 cm−1 was selected as a marker band to calculate the diffusion coefficient (D). The microstructure parameters, including contents, mean size and mean shell thickness of microcapsules, were considered to understand the diffusion behaviors under different temperatures (20, 30, 40 and 50 °C) in bitumen. The results showed that a larger mean size of microcapsules did not greatly affect the D values under the same temperature. In contrast, a higher mean shell thickness decreased the D values because of the decrement of damage probability of microcapsules under the same content. With the same microcapsule sample in bitumen, the D values presented a trend of linear increase when the content of microcapsules was increased. All these results indicated that the microstructure affected the diffusion behaviors based on the concentration of released rejuvenator. A preliminary model of diffusion behaviors of microencapsulated rejuvenator in bitumen was given based on the Arrhenius equation considering the microstructure of microcapsules, the amount of released rejuvenator and the age degree of bitumen. This model may be a guide to the construction and application of self-healing bitumen using microcapsules.

Di(biphenyl)silane and carbazole based bipolar host materials for highly efficient blue phosphorescent OLEDs

In this paper, a series of new bipolar blue host materials has been designed and synthesized by incorporating dimethyl or diphenyl silane core with connection of carbazole di(biphenyl) groups at different linking positions. The triplet energies and charge-transporting properties of these bipolar host compounds are controlled by restricting or enhancing the conjugation length among silane, biphenyl, and carbazole units. All materials exhibit good thermal/morphological stabilities. Among these host molecules diphenyldi(4-(3,5-bis-carbazol-9-yl)phenyl)phenyl silane (DM4CzDBPSi) showed the highest triplet energy (2.82 eV) and glass transition temperature (197 °C) along with optimal bipolar charge-transporting property. A phosphorescent blue organic light-emitting diode with DM4CzDBPSi silane host and FIrpic dopant system demonstrated best device performances with maximum external quantum efficiency of 20.9% and a power efficiency of 41.28 lm/W.

Iron-Catalyzed Hydrosilylation of Aldehydes and Ketones under Solvent-Free Conditions

Exposure of aldehyde or ketone to 1 mol % BIAN-Fe(C7H8) complex in the presence of diphenyl silane affords the corresponding protected alcohol in excellent yields, under mild reaction conditions. Aldehydes and ketones are reduced cleanly in the presence of a broad range of functional groups under solvent-free conditions.

Microwave-assisted hydrothermal synthesis of submicron ZSM-22 zeolites and their applications in light olefin production

There is an increased demand for facile and rapid synthesis of one-dimensional pore zeolites with controlled crystal size in the nanometer range. Here, we report for the first time, the rapid synthesis of ZSM-22 (TON) by using microwave-assisted hydrothermal synthesis (MAHyS) to control nucleation and growth. ZSM-22 crystals were synthesized rapidly in 24h (instead of 72h in conventional synthesis). Effect of synthesis time under microwave irradiation on the crystallinity of TON zeolites from 8 to 24h was investigated. The conventional hydrothermal synthesis was used for comparison. Under microwave-assisted synthesis, uniform crystal size with lower crystal aspect-ratio (length/width) was obtained and high agglomeration was prevented. Surface modification was applied by deposition of silica on the external surface of ZSM-22 using catalytic cracking of diphenyl silane. The protonated H-ZSM-22 prepared by the MAHyS and the surface-modified TON zeolites were applied in catalytic cracking of n-hexane. The modified MAHyS zeolites showed superior selectivity to propylene and lower selectivity to aromatics. Stability against deactivation was clearly observed over surface-modified ZSM-22 zeolites. The physico-chemical properties of modified zeolite-catalysts were characterized by using XRD, FE-SEM, N2 adsorption–desorption, 27Al MAS NMR and NH3-TPD.

ChemInform Abstract: Exclusive Chemoselective Reduction of Imines in the Coexistence of Aldehydes Using AuNPore Catalyst.

AbstractAldimines and enimines are chemoselectively reduced by methyl diphenyl silane even in the presence of aldehydes and ketones.

Synthesis of 4,4-diphenyl-3,4-dihydro-2H-1,4-thiasiline

4,4-Diphenyl-3,4-dihydro-2H-1,4-thiasiline (3) was synthesized starting from diphenyl(divinyl)silane by a sequence of reactions including free-radical thiylation with thioacetic acid, reduction of thioacetate to thiol, heterocyclization of the latter, oxidation and the Pummerer rearrangement of the cyclic sulfoxide to the unsaturated cyclic organosilicon sulfide. Although compound 3 is hydrolytically more stable than its Si-dimethylated analogue, both compounds are hydrolyzed to the corresponding siloxanes with the cleavage of the Si‒ Csp2 rather than the Si‒ Csp3 bond. A theoretical rationalization for this is given.

Efficient organic light-emitting diodes with low efficiency roll-off at high brightness using iridium emitters based on 2-(4-trifluoromethyl-6-fluoro phenyl)pyridine and tetraphenylimidodiphosphinate derivatives

Using 2-(4-trifluoromethyl-6-fluorophenyl)pyridine (tfmfppy) as the cyclometalated ligand and tetraphenylimidodiphosphinate (tpip) derivatives as ancillary ligands, three iridium complexes (1: Ir(tfmfppy)2tpip; 2: Ir(tfmfppy)2ftpip, ftpip = tetra(4-fluorophenyl)imidodiphosphinate; 3: Ir(tfmfppy)2tfmtpip, tfmtpip = tetra(4-trifluoromethylphenyl)imidodiphosphinate) showing phosphorescence at 514, 513 and 508 nm in CH2Cl2 were synthesized, respectively. By using these complexes as emitters, the organic light emitting diodes with the concise configuration of indium tin oxides/1,1-bis(4-(di-p-tolyl-amino)phenyl)cyclohexane (60 nm)/1 or 2 or 3: bis[3,5-di(9H-carbazol-9-yl)phenyl]di-phenyl silane (8 wt%, 30 nm)/1,3,5-tri(1-phenyl-1H-benzo[d]imidazol-2-yl)phenyl (90 nm)/lithium fluoride (1 nm)/aluminium (100 nm) showed bright green light with maximum luminance higher than 40 000 cd m−2. The maximum current efficiency (ηc) values for 1, 2 and 3 based devices (GIr1, GIr2 and GIr3) were 77.49, 66.57, and 53.26 cd A−1 at relatively high brightness of 8025, 5286 and 5169 cd m−2, respectively. In addition, the efficiency roll-off ratios from the peak efficiency to the brightness of 10 000 cd m−2 are less than 10% for all the devices. We believe that the good electron mobilities of the phosphorescent emitters lead to the high devices efficiency and low efficiency roll-off. The results suggest that these complexes have potential application in organic light emitting diodes.

Theoretical and Experimental Vibrational Spectroscopic Investigation of Two R1R2-Diphenylsilyl-Containing Monomers and Their Optically Active Derivative Polymer

FT-IR and Raman spectra of bis(4-aminophenyl)diphenylsilane (DIA) and a dicarboxylic acid containing the imide function and a L-alanine moiety (L-ALA) and their resultant polymer (PALA) were recorded in the 500-4000 cm(-1) and 400-3800 cm(-1) regions, respectively. The optically active poly(imide-amide) obtained has two sp(3) carbons in the main chain, favoring its flexibility. Raman analysis identifies the fluorescence produced by the electronic conjugation between the aromatic rings and the amidic groups, which affects the molecular fine structure. Thus, the theoretical study of the vibrational patterns has become a support and a complementary technique for the characterization of this fluorescent system. The optimized molecular geometry of the monomers and the polymeric unit using B3LYP and HF methods at the 6-31G(d) level of theory were used for the vibrational assignments. Thus, the small variations between the calculated and experimental vibration values could be related to possible intra- and/or intermolecular interactions or to the existence of a charge transfer phenomena between a donor or acceptor group within the system.

Synthesis and cure kinetics of diphenyl(diphenylethynyl)silane monomer

Diphenyl(diphenylethynyl)silane ((ph–C≡C)2–Si–ph2) (DPDPES) was synthesized by the Grignard reaction. The corresponding isothermal and non-isothermal cure kinetics of DPDPES were analyzed by using differential scanning calorimetry (DSC), and the molecular structure was characterized by H-NMR. The results showed that all the cure curves were typically sigmoid shape and cure reactions could be described by an autocatalytic kinetic model by isothermal DSC. The kinetic data, for example, activation energy (E) and frequency factor (A), were 119.22 kJ/mol and 4.67 × 107 (s−1), respectively. The non-isothermal DSC analyses showed that E and A were 162.12 kJ/mol and 1.32 × 109 (s−1), respectively, and the reaction order was 0.94. Based on the research work of this paper, it can be said that the cure reaction of DPDPES monomer was of autocatalytic and diffusion-controlled characteristics, and the effect of the diffusion was more evident at low temperature. The cure reaction of DPDPES was a first-order kinetic reaction.

Pentacoordinate mono(β-diketonato)- and hexacoordinate bis-(β-diketonato)-silicon(IV) complexes obtained from (thiocyanato-N)hydridosilanes

Three novel neutral hypercoordinate silicon(IV) complexes containing the O,O′-donor deprotonated β-diketone ligands 1,3-diphenylpropane-1,3-dione (HL1) and 1-phenylbutane-1,3-dione (HL2) were synthesized starting from the hitherto unknown diphenyl(thiocyanato-N)silane [HPh2Si(NCS)] and methyldi(thiocyanato-N)silane [HMeSi(NCS)2], a class of silicon source with Si–NCS and Si–H reactive functionalities. The reaction of HL1 with the new starting material HPh2Si(NCS) only afforded a neutral pentacoordinate silicon complex containing one β-diketonato ligand coordinated in a bidentate fashion (complex 16). The reaction of HL1 and HL2 with HMeSi(NCS)2 yielded bis-β-diketonato neutral hexacoordinate silicon complexes (17 and 18, respectively). The three compounds 16–18 were characterized using solution 1H, 13C and 29Si INEPT NMR and FT-IR spectroscopies, and compounds 17 and 18 were also studied using solid-state 29Si CP/MAS NMR. Elemental analysis and single-crystal X-ray diffraction were used to establish the composition and the structure of all of the new complexes. The 29Si INEPT NMR solution studies confirmed that compounds 16–18 maintain the same hypercoordination in solution that they have in the solid state. Compound 16 has a SiO2NC2 coordinating framework and represents the first example of a pentacoordinate silicon β-diketonato whose X-ray single crystal structure has been elucidated, and compounds 17 and 18 are the first neutral, non-zwitterionic, hexacoordinate silicon complexes with a SiO4NC coordinating framework bearing only one –NCS functionality. The usefulness of the (thiocyanato-N)hydridosilanes HPh2Si(NCS) and HMeSi(NCS)2 as starting materials for the preparation of hypercoordinate organosilicon complexes is confirmed.

Fluorescence Spectroscopic and Time-Dependent Density-Functional Theory Studies of Diphenylsilane

We investigated fluorescence and fluorescence excitation of diphenylsilane (DPS) in a solution and molecular beams in combination with the aid of the DFT method. When the molecule was photoexcited at 250 nm in a cyclohexane solution, normal and excimer fluorescences were observed in the ranges of 260-320 and 330-450 nm, respectively. The fluorescence excitation spectrum indicates that the channel leading to the intramolecular excimer formation is not efficient in comparison with the normal fluorescence. Vibrationally resolved fluorescence excitation spectra were measured for the DPS molecules cooled in pulsed supersonic expansion of He in the range 262.2-271.7 nm, in which we can see several electronic excitation spectra exhibiting the electronic band origins. We found that the simulated absorption spectrum based on the time-dependent densityfunctional theory calculations accords well with the absorption spectrum.