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Conformal chemical vapor deposition (CVD) of silicon carbide (SiC) from methyltrichlorosilane (MTS) and hydrogen (H2) onto high-aspect-ratio (HAR; typically >100:1) three-dimensional features has been a challenge in the fabrication of ceramic matrix composites. In this study, the impact of heterogeneous underlayers on the initial nucleation of SiC-CVD was studied using HAR (1000:1) microchannels with a tailored wetting underlayer of Si(100) and dewetting underlayers of thermally formed amorphous silicon dioxide (a-SiO2) and turbostratic boron nitride (t-BN). Incubation periods were distributed in the microchannels on a-SiO2 and t-BN underlayers, with the longest period of 70 min found at the feature-bottom due to a decreased concentration (C) of film-forming species. The longer incubation periods with more dewetting underlayers arose due to demoted initial nucleation. Prolonged incubation at the feature bottom led to poor conformality because thick films had already formed at the inlet when film formation began at the feature bottom. The incubation periods were eliminated by increasing the supply of MTS/H2, in accordance with classical heterogeneous nucleation theory. In the meantime, carbon-rich SiC films formed in the vicinity of dewetting a-SiO2 and t-BN underlayers at the feature bottoms, with greater carbon segregation on more dewetting underlayers. This was probably due to the deposition of pyrocarbons (CH4, C2H2, and/or C2H4) generated from MTS/H2 in the gas phase. Decreasing the temperature (T) from 1000 to 900 °C prevented carbon-rich film formation, and the expected deposition rate of pyrocarbon decreased to 0.6% for the case of CH4. A higher C of MTS/H2 combined with a lower T enabled conformal and stoichiometric film formation on the heterogeneous HAR features.

Poor interfacial bonding between diamond and matrices has limited industrial applications of diamond-containing composites. Herein, continuous and dense nanometer SiC coatings were deposited on both large size (200 μm) and small size (1.0 μm) diamond particles to improve the wettability of diamond and protect it from oxidation and graphitization. Coating procedure consisted of first pretreating diamond particles followed by chemical vapor deposition (CVD) using methyltrichlorosilane (MTS: CH3SiCl3) as a precursor. Effects of deposition temperature, time, and gas flowing rate on microstructures of SiC coatings were all studied. Results showed that diamond surfaces were fully coated by SiC with thicknesses of 30 nm and 20 nm for large and small size diamond particles, respectively. Meanwhile, onset oxidation temperatures of large and small SiC-coated diamond particles increased by 250 and 130 °C, showing greatly enhanced oxidation resistance than that of raw diamond particles. The compressive fracture strength (CFS) of SiC-coated diamond (200 μm) is 226 N, improved by 8.5% compared with that of the raw diamond (201 N). In sum, CVD method is promising for the preparation of homogeneous nanometer SiC coatings on diamond particles for its modification and further application in composites.

The development of functional relationships between the observed deposition rate and the experimental conditions is an important step toward understanding and optimizing low-pressure chemical vapor deposition (LPCVD) or low-pressure chemical vapor infiltration (LPCVI). In the field of ceramic matrix composites (CMCs), methyltrichlorosilane (CH3SiCl3, MTS) is the most widely used source gas system for SiC, because stoichiometric SiC deposit can be facilitated at 900 °C–1300 °C. However, the reliability and accuracy of existing numerical models for these processing conditions are rarely reported. In this study, a comprehensive transport model was coupled with gas-phase and surface kinetics. The resulting gas-phase kinetics was confirmed via the measured concentration of gaseous species. The relationship between deposition rate and 24 gaseous species has been effectively evaluated by combining the special superiority of the novel extreme machine learning method and the conventional sticking coefficient method. Surface kinetics were then proposed and shown to reproduce the experimental results. The proposed simulation strategy can be used for different material systems.

Poly(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofibers (flexible and effective bonding together) were combined with stiff and flame-resistant sepiolite nanorods (SEP) to fabricate composite nanofibrous aerogels (NFAs) through a versatile and gelation-free freeze-drying method. The PVA-co-PE nanofibers prepared based on a high-yield Melt-Extrusion-Phase-Separation process could form a continuous fibrous structure, and the fibrous networks and surface wettability of composite NFAs could be tuned by the amount of SEP used. The introduction of an appropriate amount of SEP improved mechanical properties of composite aerogels, while excessive SEP would lead to a decrease in compression strength of them. The mechanical properties of composite NFAs are shown to be governed by a combination of stiffness of SEP and effective bonding of PVA-co-PE nanofibers. More importantly, the presence of SEP can substantially improve flame resistance of aerogels. After a simple thermal chemical vapor deposition treatment with methyltrichlorosilane, the surface of composite NFAs become rougher and siloxane nanoparticles became visible. With this deposition, hydrophilic NFAs became hydrophobic as a significant surface property modification. Furthermore, the maximum stress at 60% strain went up from 15.57 to 19.17 kPa and the resilience of composite aerogels improved. Thermal properties results confirmed silane coating can improve the thermal stability and insulation characteristics of polymeric aerogel. The manufactured NFAs are demonstrated as good thermal insulators (0.0274 W m−1 K−1), excellent refractories, efficient water/oil separators (45–108 g/g, 78.58–91.76%) and reusable absorbers. Consequently, the multifunctional silane-coated PVA-co-PE/SEP composite NFAs could be envisaged for several demanding applications.

We have discovered herein that commonly used laboratory glass microfiber filters can be functionalized as background-free superhydrophobic substrates for quantitative fluorometric assays. In particular, glass microfiber filters (Whatman GF/A) can be treated with low-concentration (20 mM) methyltrichlorosilane/toluene solution to be superhydrophobic (water contact angle >150°) in less than 5 min; the modified glass microfiber filter can be readily patterned with UV/ozone irradiation to create hydrophilic reaction zones on the otherwise superhydrophobic substrate. Compared with traditional cellulose filter paper, the glass microfiber filter has extremely low fluorescence background, which makes it an excellent substrate for preparing quantitative fluorometric assays. In conjunction with smartphone imaging and color analysis, we have showcased a copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC)-based fluorometric assay for copper quantitation on these patterned, superhydrophobic glass microfiber filter substrates. Both the limit of detection and linear response range are comparable with the standard spectrophotometric quantitation in solution and commercial copper detection kits, which augments the application potential of superhydrophobic glass microfiber filters as ideal (e.g., background-free) substrates for the preparation of multiplex microassays and other advanced microanalytical devices based on fluorescence readout.

A SiC and ZrC composite coating layer on a tristructural-isotropic (TRISO) coated particle was deposited by fluidized bed chemical vapor deposition method. Methyltrichlorosilane (MTS) and ZrCl4 powder were used as the source materials of the SiC coating and the ZrC coating, respectively. Two kinds of the SiC and ZrC composite coating layers were fabricated with other source gas fraction. The composite coating layer, with a similar ratio of SiC and ZrC, which was observed in the SEM microstructure, was fabricated, and each phase was confirmed by XRD, Raman, and TEM analysis. Only the SiC and ZrC phases were co-deposited; the ZrSi and free carbon phases were not. The composite coating layer with very small ZrC particles embedded in a SiC matrix was fabricated by decreasing the ZrCl4 source gas ratio. Nano-sized ZrC particles in the coating layer were confirmed by high resolution TEM and EDS analysis.

A polyacrylonitrile (PAN)/polydimethylsiloxane (PDMS) flat membrane was fabricated by electrospinning technique and modified using titanium dioxide (TiO2) nanoparticles and low-energy materials, dimethyldichlorosilane (MeSiCl2)/methyltrichlorosilane (MeSiCl3), to obtain a hydrophobic surface. The new membrane was utilized for the electromembrane extraction (EME) of model molecules including dibutyl phthalate (DBP) and bis [2-ethylhexyl] phthalate (DEHP). The parameters affecting proposed EME were optimized by the response surface methodology (RSM) based on the central composite design (CCD). The optimized values were 200 V of voltage, 20 min of extraction time, 1100 rpm of agitation rate, 10 mL of donor phase volume and 1 mL of acceptor phase volume. From the results, the performance of EME with the new (modified) membrane remained almost constant after ten extraction cycles while the extraction performance of unmodified EME steeply fell after six extraction cycles. The limits of detection (LODs) for DBP and DEHP were 7.40 and 0.08 ng mL−1, respectively. The linear dynamic range (LDR) was in the range of 100–4000 ng mL−1 for DBP and 1–2000 ng mL−1 for DEHP. The relative standard deviations (RSDs) were below 10%, and the relative recoveries were over 86%. The overall energy consumption for the extraction of the model molecules by new EME was 13.4 kWh m−3. The approach is time-efficient and cost-effective, as the fabricated membrane has better reusability than the previous membranes used for EME.

The previous studies showed that the SiC layer with sub-micro grain structure can prevent fission products release more effectively. Usually, the silicon carbide (SiC) layer in TRISO (Tristructural isotropic) particles was deposited at 1500–1600 °C by spouted bed chemical vapor deposition (CVD) from methyltrichlorosilane in H2 environment. It has grain size in micro scale (1–10 μm). In this work, we proposed a novel method for preparation of sub-micro grained SiC layer by adjusting the deposition parameters. The as-prepared SiC layer had grain size about 200 nm and pure phase (β-SiC). The fined grain SiC layer also exhibited higher mechanical property than SiC layer with larger grain size.

Water pollution due to oil spills has become a significant concern in recent times for the marine ecosystem. The use of oleophilic/hydrophobic sorbents for oil–water separation has gained a lot of attention as an economical and environment-friendly solution. Herein, we developed a superhydrophobic/superoleophilic cotton by silica nanoparticles (~ 800 nm) treatment followed by surface functionalization with methyltrichlorosilane (MTCS). X-ray diffraction, field emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and Fourier-transform infrared spectroscopy studies reveal that the formation of pseudo-amorphous SiO2 NPs and a C–Si–O coverage on cotton fiber render it superhydrophobic with increased surface roughness. The MTCS/SiO2-treated cotton exhibited contact angles of ~ 173 ± 2° and 0° on the water–cotton and oil–cotton interface, respectively. Moreover, the MTCS/SiO2-treated cotton demonstrated superhydrophobicity over the entire pH range, with excellent absorption capacities for various oil–water mixtures ranging from ~ 30 to 40 times its weight.

A flexible, stretchable and electrically conductive nanofiber composite with superhydrophobicity was fabricated by ultrasonication induced carbon nanotubes (CNTs) decoration onto the polymer nanofiber, followed by methyltrichlorosilane (MTS) modification. The introduction of CNTs and polysiloxane derived from MTS improved the superhydrophobicity, conductivity, thermal stability and mechanical properties of the nanofibrous membrane. The superhydrophobicity and electrical conductivity could be maintained during the cyclic stretching. The nanofiber composite membrane could be utilized to separate the oil from the oil/water mixture regardless of pH of water, exhibiting a large flux, high efficiency and good recyclability.

The subject of slippery liquid-infused porous surfaces (SLIPS) have attracted many researchers due to their excellent liquid repellent properties and widespread usage in many fields such as anti-wetting, anti-icing, omniphobic, self-cleaning and anti-biofouling surfaces. Choosing an environmentally friendly, durable lubricant and easy-clean preparation method is very important when designing SLIPS. In this work, fluorine-free, transparent, water and oil repellent slippery liquid-infused porous surfaces (SLIPS) were successfully obtained via infusing silicone oil, which is a fluorine free and durable liquid, onto superhydrophobic polysiloxane nanofilament surfaces. Polysiloxane nanofilaments were prepared on activated glass slides by an easy, clean and environmentally friendly gas phase reactions of n-propyltrichlorosilane (n-PTCS) for the first time and also methyltrichlorosilane (MTCS) and the results were compared. Advancing contact angles of the n-PTCS based polysiloxane nanofilament layers were between 143 and 172 degrees and contact angle hysteresis as low as 7 degrees was obtained on these surfaces by altering the relative humidity and reaction time during filament growth. Then, transparent SLIPS were obtained by infusing silicone oil into polysiloxane filament layers of MTCS and n-PTCS. The obtained SLIPS shows excellent liquid repellency, very low contact angle hysteresis for long durations and maintains its water repellency after heating up to 80 degrees C for 6 days and also after exposure to continuous water droplet flow up to 2 h.

Dual-component fibrous materials were produced by co-extrusion and multiplication technology in combination with a water jet procedure. High density polyethylene/poly(vinylidene fluoride) (HDPE/PVDF) and polypropylene/high density polyethylene (PP/HDPE) systems were obtained. Modification of these fibrous materials with multiwall carbon nanotubes imparted electrical conductivity. Methyltrichlorosilane treatment permitted to reach superhydrophobicity reflected in a water contact angle (WCA) ≥ 160°. Both types of modification decreased a pore size of HDPE/PVDF fibrous material and strongly increased its surface area. The material subjected to both treatments possess pore size of 3.1 μm. This electrically conductive and superhydrophobic HDPE/PVDF fibrous material is characterized by WCA of 164° and low surface resistivity of 87.4 Ω/sq. Electrochemical modification using cyclic voltammetry resulted in the formation of silver nanoparticles (Ag°) on surfaces of the fibers, which imparted antibacterial properties against Staphylococcus aureus and Escherichia coli. Keywords: Smart materials, Dual-component fibrous materials, Lotus effect, Multiwall carbon nanotubes, Cyclic voltammetry

A functionalized nanofiber membrane with high oil/water separation efficiency and methylene blue adsorption has been successfully fabricated by electrospinning and a surface modification approach. The substrate poly(lactic acid) (PLA) nanofiber film was firstly coated with titanium dioxide (TiO2) nanoparticles (NPs) by the sol–gel method. Then, polysiloxane formed by the hydrolysis and polycondensation of methyltrichlorosilane (MTS) was deposited on the modified nanofiber surface to increase the surface roughness and reduce the surface energy. The PLA nanofibrous membrane functionalized with TiO2 NPs and MTS exhibited excellent superhydrophobicity (water contact angle = 157.4 ± 0.9°), high permeation flux (2297.6 ± 51.6 L m−2 h−1) and ideal filtration efficiency (98.4 ± 1.0%). Moreover, the functionalized nanofibrous membrane could also achieve rapid and recyclable adsorption of toxic dyes such as methylene blue in aqueous solution. It provides a new prospect to facilely fabricate nanofibrous membrane materials to achieve the dual functions of oil/water separation and removal of toxic dyes with high efficiency.

Effective removal of oil spills or organic pollutant oils from water is of global significance for environmental protection. However, traditional techniques usually suffer from the limits of low efficiency and high cost. In this study, sponge-like polyamide 6/organic montmorillonite (PA 6/OMMT) composite absorbents were fabricated through a large-scale solution foaming method. Aqueous sodium carbonate solution was injected into a PA/formic acid solution with well-dispersed nanoclay to generate CO2 and meanwhile initiate the phase separation of PA molecules from the solvent. Both mesopores and macropores existed in the prepared sponges. The effect of OMMT content on the microstructures and adsorption properties was investigated. Upon increasing the OMMT fraction in composite sponges, the pore size decreased and the fraction of mesopore increased. Better adsorption properties were thus obtained. When OMMT nanoplatelets accounted for 10%, the corresponding sponge had an uptake capacity of 12.5–22.1 g g−1 for diverse oils or organic solvents. Moreover, the composite sponges absorbed oils and organic solvents rapidly and reached saturation in 20 s. When it was coated with methyltrichlorosilane (MTS), the static water contact angle on the surface of the sponge increased from 88° to 115°. The selective absorption of oil from an oil/water mixture was improved. A greatly promising approach is provided to make commercial polyamide into highly porous functional materials for the cleanup of large-scale oil spills.

Superhydrophobic silk fabrics were prepared using an environmentally friendly enzyme-etching approach, followed by the modification with methyltrichlorosilane (MTCS) via a simple thermal chemical vapor deposition (CVD) process at 70 °C. The effects of the concentration, treatment time and temperature of enzyme on the etched surface properties were discussed. The composite superhydrophobic silk fabrics demonstrated excellent self-cleaning ability, relatively unscathed effecting their intrinsic properties such as the luster, softness, color and style of the fabrics. Furthermore, these treated fabrics demonstrated excellent mechanical durability after silane-treatment as evidenced by the cyclic abrasion and laundering tests. The composite superhydrophobic cotton fabrics have also demonstrated a high efficiency in oil-water separation. The facile technology via enzymatic hydrolysis to etch the substrate possesses extensive potential applications on various other cellulose-based substrates. Accepted version

To reduce the flammability, hydrophobic silica aerogels (SAs) were modified by replacing commonly used trimethylchlorosilane (TMCS) with methyltrichlorosilane (MTCS). It was observed that the MTCS modified SAs (MSA) showed similar physicochemical properties to those TMCS modified SAs (TSA), including the density, thermal conductivity, hydrophobicity, and even thermal stability. However, the flammability of MSA was observed much lower than that of TSA, which was reflected by the significantly decreased gross calorific value (GCV). Furthermore, it was known from the kinetic and thermodynamic analyses that the pyrolysis of MSA became more difficult with the increasing conversion rate (α), which was evidenced by the fact that the apparent activation energy (E) kept rising to about 194 kJ/mol during the whole pyrolysis. Based on the changed E along the time, the pyrolysis process could be divided into two stages, in which α = 0.4 was considered as the turning point. Those main thermodynamic parameters, including pre-exponential factor (A) and the changes of enthalpy (ΔH) and entropy (ΔS), showed a quite consistent tendency with the E, whereas the change of Gibbs free energy (ΔG) almost kept unchanged. The research outcome of this study can provide a deep understanding of the pyrolysis process of SAs and render the public realize the thermal hazard risk of SAs.

An efficient method for synthesis of well-defined, well-characterized, tadpole-shaped polystyrene with a single atom junction point that is optimal for the study of dynamics has been developed using anionic polymerization, silicon chloride linking chemistry, and metathesis ring closure. The difunctional macromolecular linking agent, ω-methyldichlorosilylpolystyrene, was formed by reacting sec-butyllithium-initiated poly(styryl)lithium with excess (30×) methyltrichlorosilane to eliminate formation of linear dimer and three-arm star polystyrene. The asymmetric, three-arm, star precursor was formed by linking excess α-4-pentenylpoly(styryl)lithium (α-PSLi) with the macromolecular linking agent, and the excess α-PSLi functionalized with ethylene oxide before termination with methanol to facilitate chromatographic separation. Cyclization of the three-arm, star precursor to form tadpole-shaped polystyrene was effected in methylene chloride at high dilution using the Grubbs first generation catalyst, bis(tricycl...

Изучена реакция силилирования двуводного гипса диметилдихлорсиланом и метилтрихорсиланом. Исследованы продукты силилирования., The silylation reaction of gypsum dihydrate with dimethyldichlorosilane and methyltrichorsilane has been studied. The products of silylation have been investigated., Естественные и технические науки, Выпуск 6 (157) 2021

The design of future jet engines has to meet the requirements of lower pollutant emission and higher efficiency. One of the main pollutants is soot particulates, whose emission negatively affects the global climate and human health. As a result, minimizing soot formation in jet engines can reduce both the economic and social costs of transportation. In addition to minimizing soot formation, the overall efficiency of jet engines can be improved by replacing the current metal super-alloy materials with ceramics matrix composites (CMCs), particularly silicon carbide matrix/silicon carbide fiber (SiC) composites. SiC composites offer similar, if not better, maximum service temperature to the nickel-based super-metal alloys, but only at one-third of the weight. Employing the composites will increase 1) the combustion efficiency with higher allowable flame temperature, 2) the engine thrust with smaller air flow diverted for cooling, and 3) the fuel mileage with lighter engines. However, there exists a number of challenges that hinder the achievement of minimal soot formation and cost-effective production of SiC composites. Numerous research efforts have been dedicated to tackling these challenges. Such efforts have resulted in a large number of detailed chemical kinetic models whose purpose is to predict the soot formation and SiC composite fabrication processes in CFD simulations. Unfortunately, the models are still facing two major limitations: 1) significant uncertainties in reaction rate coefficients and 2) huge numbers of species and reactions that render the models impractical for complex CFD simulations. In order to overcome these two limitations, there exists a need for fundamental experimental data to 1) minimize the reaction rate coefficient uncertainties, and 2) reduce the model size while preserving their performance for practical CFD simulations. Recognizing this need for experimental data, the Reacting Flow Laboratory (RFL) at the University of Virginia (UVa) has constructed and verified an excellent analytical system for chemical kinetic studies. The main component of the analytical system is a microflow tube reactor (MFTR), which can be paired with different diagnostic tools to quantify stable and radical gaseous species, and solid products during thermal and oxidative decomposition of hydrocarbon fuels or other chemicals of interest. This thesis work employed the established analytical system to study thermal decomposition (pyrolysis) of three different hydrocarbon fuels: ethylene, n-dodecane and Jet A. The objectives were to investigate the effects of temperature, residence time and fuel chemical composition on the formation of soot precursors in the gas phase. Besides traditional chemical kinetic models, the experimental data were also used to test a new concept in modeling real jet fuels: the Hybrid Chemistry (HyChem) approach. This approach considers combustion of jet fuels as a two step process. The fuel initially undergoes thermal or oxidative decomposition to produce about ten products, which then get oxidized to form the final combustion products. Given that the HyChem approach represents the fuel chemical composition by the pyrolysis step, it needs to be thoroughly examined in order to ensure that the HyChem approach can accurately model the jet fuel combustion. In addition to pyrolysis of hydrocarbon fuels, this thesis work also employed the analytical system to investigate species transport and chemical kinetics during silicon carbide (SiC) deposition from pyrolysis of methyltrichlorosilane/hydrogen (MTS/H2) mixtures. First of all, the functionality of the analytical system to study the SiC deposition process was demonstrated with a set of SiC deposition experiments on quartz substrate over a wide range of experimental conditions. Then, the analytical system was used to investigate the formation of SiC precursors in the gas phase during pyrolysis of MTS/H2 mixtures. With the measured speciation data, optimization and simplification of a detailed chemical kinetic model was carried out. The result was an improved model with less than half the number of species and reactions.

The effect of pyrolytic carbon (PyC) thickness on the tensile property of mini T800-carbon fiber reinforced SiC matrix composites (mini-C/SiC) was studied in this work. PyC interphase was prepared by chemical vapor infiltration (CVI) process using C3H6-Ar as gas source, and the PyC thickness was adjusted from 0 to 400 nm, then the SiC matrix was prepared by CVI process using methyltrichlorosilane (MTS)-H2-Ar as precursor and gas source. The results showed that the tensile strength of mini-C/SiC increased first and then decreased with the increase of the PyC thickness. When the thickness of PyC was 100 nm, the average strength reached the maximum value of 393±70 MPa. The Weibull modulus increased from 2.0 to 8.06 with the increase of PyC thickness, the larger the Weibull modulus, the smaller the dispersion, which indicated that the regulation of PyC thickness is conducive to improve tensile properties.

Membrane distillation is a promising thermally driven separation process that can be used for water desalination. The primary requirement of this technique is the hydrophobicity of the membrane, so polymeric membranes are mainly used as the ceramic ones are intrinsically hydrophilic. In this work, in order to modify the water wettability, Al2O3 commercial tubular membranes with different pore sizes were functionalized using methyltrichlorosilane. The main aim of the work was to verify in depth the effects and the success of this hydrophobizing treatment. The effect of silanization on pore size and geometry was evaluated using scanning electron microscopy as well as gas permeation in order to highlight possible morphological changes in the membrane structure. No evident modification was detected. The hydrophobicity was assessed by measuring water contact angles which increased from about zero for the pristine supports up to 145° for the modified membranes. After treatment, the water entry pressures ranged between 0.7 and 2.1 bar. Further analyses were carried out in order to elucidate the amount of silicon grafted to the Al2O3 particles and its distribution. Finally, the modified membranes were tested in a vacuum membrane distillation plant at different temperatures (50, 70 and 90 °C) using as feed both deionized water and a highly concentrated NaCl solution (90 g/L). Very satisfactory performances were obtained. The permeate fluxes were comparable – or even higher – to those registered for a polypropylene membrane used as a reference. The separation properties were evaluated during the NaCl solution tests and were close to the full rejection of salt in any operating condition.

Due to the severe impacts on the ecological environment and human life caused by oil leakage and organic solvent contamination of water bodies, a splendid absorption material is strongly demanded to remove the organic contaminants. In this research, we fabricated the superhydrophobic and superoleophilic absorption material of the ethylene-propylene diene monomer (EPDM) foam rubber modified with methyltrichlorosilane (MTCS) through a facile two-step approach including chemical coarsing and sol-gel process. The resultant foam rubber displayed favorable oil/water selectivity and strong repellence to water with contact angel of up to 159.3°. The prepared material displayed high absorption capacity for oils with a wider range of viscosity (from 0.3 to 400 mPa·s) and high oil/water separation efficiency of nearly 99.9%. More importantly, the as-obtained foam rubber exhibited an outstanding reusability and durability to both organic solvent and at least 100 cycles of mechanical compression, demonstrating its promising potential to serve as an absorbent in practical oil/water separation.

Methylchlorosilanes (MSCs) of the type (CH3)nSiCl4−n (n = 1, 2, 3) are usually used for surface modification of silica aerogels (SAs), in which the quantity of Si–Cl and Si–CH3 groups deeply affects the properties of prepared SAs. In this work, methyltrichlorosilane (MTCS, n = 1), dimethyldichlorosilane (DMDCS, n = 2), and trimethylchlorosilane (TMCS, n = 3) were used to modify wet gels and the effects of Si–Cl and Si–CH3 groups’ quantity on microstructures and surface properties were explored in detail. It turned out that the MTCS modified SA (MSA) possessed the most compact and nonuniform three-dimensional nanostructure among the three SAs, accompanied by the biggest density of ~ 0.14 g/cm3. Further investigations demonstrated that all the three SAs had similar BET surface area of about 900 m2/g and average pore size of 10–15 nm. Though FTIR analysis presented the discrepancies obviously among the three SAs, the thermal stability of the three SAs was similar, with the onset and peak temperatures in the exothermic reaction of methyl groups being ~ 240 °C and ~ 270 °C, respectively. The best hydrophobicity belonged to the TSA, verified by the biggest contact angles of 155°. Thus, all these indicated that the properties of the three SAs were deeply related to the quantity of Si–Cl and Si–CH3 groups in MCS.

Size control of silica hollow particles was achieved using a water-in-oil (W/O) emulsion system, where interfacial condensation of organosilanes (octyltrichlorosilane and methyltrichlorosilane) took place around the aqueous droplets. Good emulsion stability was obtained using soybean oil as the oil phase because of its high viscosity. This high stability led to bimodal distributions in the sizes of the aqueous droplets and final hollow particles, with particle sizes observed of a few tens of nanometers and a few micrometers. The presence of NaCl was found to be required in the water phase to afford uniform-sized silica hollow spheres. Hydrolysis of the organosilanes caused a supersaturation of the aqueous NaCl solution dispersing in the oil continuous phase, followed by crystallization from droplets. Nanosized aqueous droplets acted as a template to form uniform-sized nanospherical hollow silica particles as a result of the diminishing number of larger aqueous droplets.

Pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), an antioxidant widely applied in the plastic industry, was used to assist thermal reduction of graphene oxide (GO) on a cotton fabric in air. l-ascorbic acid was also applied for comparison. GO was deposited on the fabric by the padding method. Reduction of GO deposited on fiber surfaces at 180 and 220 °C in air imparted electrical conductivity. For all the materials the conductivity worsened after the reduction during cooling and during the first hours of storage at room conditions. However, the most stable effect of GO reduction was achieved using pentaerythritol tetrakis(3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate), which assisted the reduction of GO at both 180 and 220 °C, and allowed to obtain the cotton fabric with a stable surface resistivity of 6.6 and 3.7 MΩ/sq, respectively. Moreover, superhydrophobicity of the conductive fabric was achieved by modification with methyltrichlorosilane in an anhydrous environment.

Oil removal or oil/water separation from the industrial waste water especially under harsh environment such as acid and alkali solutions have now been becoming an urgent task for human being. Here, flexible nanofibrous membrane with super-hydrophobicity/super-oleophilicity was prepared through a facile one-step solution-immersion approach, i.e., the poly(vinylidene fluoride) nanofiber mat modified with methyltrichlorosilane (MTS). The nanostructured polysiloxane with different morphologies including the ultrathin cylindrical wires and particles, were present on the nanofiber surface after MTS hydrolysis and subsequent condensation, which significantly enhanced the surface roughness and hence the hydrophobicity of the membrane. The influence of MTS concentration in the n-hexane solution and the hydrolysis time of MTS on the morphology of polysiloxane decorated nanofiber and hence the super-hydrophobicity was investigated in detail. The super-hydrophobic nanofibrous membrane could repel hot water and corrosive solutions, and the contact angle maintained around 150° with a pH ranging from 1 to 13. It was found that the oil/water separation with a high flux and efficiency was achieved by using the nanofibrous membrane that could not only separate the oil with the pure water and hot water but also the corrosive solution including the salt, acid and alkali solution. The organic/inorganic hybrid nanofibrous membrane may have find its potential applications in oil/water separation under a harsh environment.

Silicon carbide (SiC) layers were deposited onto alumina particles in a microwave plasma-assisted spouted bed reactor using methyltrichlorosilane (MTS) and hydrogen mixtures, in argon, as precursor gas feed. The operating parameters studied were enthalpy, gas composition, and pressure. Microwaves were guided from a generator, operating at 2.45 GHz, along a rectangular waveguide intersecting a quartz tube, acting as the reaction zone. A graphite nozzle at the bottom of the tube facilitated the spouting action. Growth rates varied from 50 to 140 μm/h. Overall results indicate that the optimal region for SiC deposition requires relatively high enthalpy (∼5 MJ/kg) and pressure (>−60 kPa) conditions, with hydrogen-to-MTS ratios ∼5:1. The quality (i.e. crystallinity, particle size, Si/C ratios) of the layers improve at these conditions, at the cost of decreased deposition rates. Characterisation was done by XRD, FTIR, XPS, SEM, TEM and EDX, which assisted in developing colour and morphological charts to indicate the changes as a function of changing operating parameters. A microwave plasma spouted bed reactor is demonstrated to be a viable alternative technique for SiC layer deposition onto microspheres.

In this study, we thermodynamically reviewed the suitable growth process conditions of α-SiC in the Si-C-H system using tetramethylsilane (TMS) and in the Si-C-H-Cl system using methyltrichlorosilane (MTS). In the Si-C-H-Cl system, pure solid SiC was obtained at high temperatures under a larger range of hydrogen dilution ratios than that tolerated in the Si-C-H system. X-ray diffraction and micro-Raman analysis of the products obtained at 1900, 2000, and 2100 °C showed that the α-SiC becomes more dominant with increasing temperature in the Si-C-H-Cl system. While TMS was unsuitable for high temperature processing due to its high C/Si ratio, MTS was found to be appropriate for growing α-SiC crystals at high temperatures under a range of conditions. These results indicate that a novel method to grow α-SiC single crystals through HTCVD using MTS as a precursor could be established.

In this report, a people-considered waste-candle soot generated from incomplete combustion of the middle zone of candle was used to coat the glass slide for fabricating the superhydrophobic surface. The candle soot coating surface followed by deposition of methyltrichlorosilane (MTCS) was characterized through field emission scanning electron microscope, contact angle measurement in air and oil, self-cleaning test, high temperature, and corrosive liquid resistance test and water drop impact experiment, respectively. Interestingly, the candle soot layer after deposition of MTCS presented a coral-like structure and exhibited high water contact angle of 161° and a low sliding angle of 3° in air, which demonstrated that it had excellent superhydrophobicity in air. Of course, the coating also exhibited high water contact angle and low sliding angle in oil. Apart from that, results of high temperature and corrosive liquid resistance tests implied that the superhydrophobic coating can keep stability after treatm...

Mesoporous polymeric aerogels with high compressibility and durability have attracted great attention due to their environmentally sustainable applications. However, it is still challenging to develop polymeric aerogels in a simple, low-cost and mass produced way. Herein, we report a strategy to prepare a high porosity polymeric nanofibrous aerogel (referred to as NFA) by direct freeze-drying of the poly(vinyl alcohol-co-ethylene) (PVA-co-PE) nanofibrous suspension. It is noteworthy that this process is free of gelation and any solvent exchange. In addition, the PVA-co-PE nanofibers were mass-produced from our production line, based on a high throughput Melt-Extrusion-Phase-Separation technique. Additionally, the network of the NFA aerogels can be tuned by the host–guest assembly of the nanofibers and the foreign PVA nano-lamellae from disordered/ordered cellular to a leaf-like structure. Further modification of the NFA by gaseous methyltrichlorosilane (MTS) led to covalently bonded siloxane nanoparticles formed on the surface, thereby facilely realizing the nanofibrous aerogel from hydrophilic to hydrophobic as well as achieving excellent resilience. The corresponding hydrophobic aerogel (designated as HNFA) possessed a slightly larger density of 11.1 mg cm−3 with an almost unchanged porosity of 99% and meso–macroporous pores of 5–100 nm compared with the NFA (8.3 mg cm−3). They are demonstrated as good thermal insulators (0.033–0.044 W m−1 K−1), high-performance air filters (99.2% filtration efficiency with 64 Pa pressure drop), organic pollutants absorbers (2500–5329% weight gain) and continuous water/oil separators. Therefore, this study opens up a new approach for simple and large-scale preparation of polymeric aerogels for versatile applications.

With good thermal properties, dielectric property and high-temperature ceramics performance, silicon-containing arylacetylene resin (PSA) has opened an attractive alternative to high performance thermosetting resins in application in the area of aircraft and missile. However, it is difficult to introduce silicon into the main chain of organic arylacetylene. In this paper, branched silicon-containing arylethyleneacetylene (BSA) resin was synthesized by methyltrichlorosilane and diethynylbenzene with zinc powder as catalyst. The advantages lie in simple operation, short reaction period and mild heat release. BSA resin exhibits excellent processability with the processing temperature of 20?C - 150?C and processing window of 130?C. The glass transition temperature of the resin casting is over 500?C. The temperature of 5% weight loss (Td5) is up to 575?C and char yield of thermoset at 800?C (Y800) reaches 91% under nitrogen. Also, the dielectric constant and dielectric loss of casting has no change within 10 - 106 Hz.