Methyl Silicone Research Articles

Mechanically strong wood-based composite aerogels as oil adsorbents and sensors

This work reported a top-down strategy to develop wood-based composites by combining wood skeleton (WS) aerogel with Polydimethylsiloxane (PDMS). WS aerogel was extracted by extensively removing lignin and hemicellulose from natural wood followed with freeze-drying. The hypothesis is that the introduction of hydrophobic PDMS into WS aerogel is of great importance for improving its mechanical performance and expanding the potential applications. To this end, WS/PDMS composites were developed by forming PDMS-infiltrated-wood skeleton via immersion and polymerization after curing treatment. We further adjusted the infiltrated PDMS concentration from 1 wt% to 30 wt% to explore the mechanical properties of the developed wood-based composite aerogels. As a result, both WS/PDMS-1 (with infiltration of 1 wt% PDMS) and WS/PDMS-30 (with infiltration of 30 wt% PDMS) performed significantly improved compression performance and shape stability compared with WS aerogel. Besides, with the assistance of surface-heating treatment on WS (HWS), the obtained HWS/PDMS-1 were used as adsorbing agents and showed fast adsorption rate with a capacity of 12 g/g (methyl silicone oil). Alternatively, by increasing the PDMS content, the obtained WS/PDMS-30 exhibited excellent compression strength and cycling stability, which could be assembled into sensor devices. We believe that this strategy may facilitate the development of strong wood-based composites with interesting features.

Lubricating organohydrogel with ultrahigh durability and super-weatherability enabled by molecular chains aligned strategy for drag-reduction coating

Lubricating hydrogel (LHO) is regarded as one of the promising candidate materials for protective coating desirable to provide drag-reduction and energy-saving functions. However, the state-of-the-art LHOs have poor durability in harsh conditions due to mechanical strength limitations and the absence of the weather resistance regime. Here we report a molecular chains aligned strategy driven by the methyl silicone oil submerging poly(oxy-1,4-butanediyl)(PEG)-polydimethylsiloxane (PDMS)matrix interior to significantly enhance the durability of lubricating organohydrogel while simultaneously making them tolerate harsh conditions. Via aligned state-driven effects, the methyl silicone oil could accelerate the aligned arrangement of the PEG-PDMS molecular chains via interface phase exclusiveness, which can greatly facilitate the mechanical toughness of lubricating organohydrogel, leading to the remarkable longevity and wear stability. Moreovre, the extraordinary weather-fastness of lubricating organohydrogel was achieved by combining the intrinsic constant feature (featuring a high boiling point and low freezing point) of methyl silicone oil and subzero temperature inhibition-freeze effect of hydrogen bonds. The lubricating organohydrogel shows high longevity and wear stability (over 18,000 friction cycles), excellent drag-reduction performance (friction coefficient is as low as 0.08), and superior tolerated-extreme environment capacity (withstand −40° to 150 °C temperature). As a drag-reduction coating, the lubricating organohydrogel demonstrates extraordinarywear-protection and anti-icing performance. These observations indicatefresh friction-reduction and energy-saving engineering materials.

Boron-Doped Methylated Amorphous Silicon for Negative Electrodes in Li-Ion Batteries

In spite of its outstanding capacity for alloying with lithium, silicon cannot be practically used as a negative electrode for Li-ion batteries: its large volume expansion upon lithiation leads to a poor capacity retention [1]. Promising results have been obtained by incorporating methyl groups in amorphous silicon (methylated amorphous silicon). This material exhibits an improved stability upon electrochemical cycling while keeping a capacity close to that of pure silicon [2]. However, the conductivity of methylated amorphous silicon may be a strong limitation, especially at high methyl content: for example, 10% methylated amorphous silicon is 10000 more resistive than pure amorphous silicon.Doping is a well-known method to enhance the electronic conductivity of semiconductors, even if the dopant activity is lower in amorphous semiconductors than in crystalline ones. 2% boron doping increases the conductivity of 10% methylated amorphous silicon by five orders of magnitude compared to the undoped material.Boron doped methylated silicon thin films (100nm thick) with various methyl content were cycled in the range 0.025V – 1V at C/2 rate (electrolyte: LP30 with 5%FEC). 10% methylated amorphous silicon with 2% boron doping exhibits a capacity retention of 70% after 500 cycles of full lithiation/delithiation, an improved performance as compared to the undoped material (see Figure 1a). Interestingly, boron doping allows for using higher methyl content without demanding pre-conditioning procedures for the electrochemical cycling of the material. The stability upon cycling is found to be further increased for 15% and 20% methylated electrodes, with a capacity retention exceeding 80% over 1000 cycles of full lithiation/delithiation (Figure 1b). This figure comes at the expense of a decreased total capacity (which remains 3 to 4 times larger than that of the current carbon electrodes). The SEI evolution and structural changes are currently investigated using operando ATR FTIR and ex-situ Raman spectroscopies, in order to rationalize the factors limiting the Coulombic efficiency to 99.7%.

Thermally stable gold nanorod dispersed silicone composite with plasmonic resonance in the optical communication window

Gold nanorods (AuNRs) possess a high optical nonlinear coefficient, ultrafast optical response speed and widely tunable localized surface plasmon resonance (LSPR) wavelength covering the visible and near infrared region. Therefore, they are extensively investigated for many optical applications. However, the poor thermal stability of the AuNRs seriously restricts their practical performance. In addition, for many applications, such as optical communication or laser modulation, AuNRs have to be combined with transparent solids, for example polymers, glass or crystals to make devices. Here, we report on the preparation of 0.23 mg AuNR dispersed methyl silicone resin (MSR) with longitudinal LSPR (L-LSPR) wavelength (1450 nm) in the optical communication window. We found that AuNR-silicone composites possess high thermal stability. After calcination in ambient environment at a temperature of 250 °C for 10 h, the L-LSPR peak of the sample can remain longer than 1380 nm, implying that the NR shape of the Au particles was well maintained. Using the open-aperture Z-scan technique, the nonlinear absorption coefficient of the composites was measured as −11.71 cm GW−1, higher than many nonlinear materials. Thus, the thermally stable AuNR@SiO2-MSR composite with high nonlinearity is promising for practical applications in the optical communication window.

Improvement in hygroscopic property of macro-defect free cement modified with hypromellose/potassium methyl siliconate copolymer and pulverized fly ash

Improvement in hygroscopic property of macro-defect free cement modified with hypromellose/potassium methyl siliconate copolymer and pulverized fly ash

Experimental study of surface roughness on improving the tribological performance of sealing pairs in magnetorheological damper

Comprehension of the tribological behavior of magnetorheological fluid (MRF) is crucial in many fields, particularly those related to seal wear. The sealing conditions are more complex than traditional media due to composition and rheological characteristics of MRF. The sealing pairs are prone to wear failure when in contact with magnetic particles. To this end, the paper focuses on the influence of surface roughness on MRF tribological properties with and without magnetic field. The whole experiment is carried out by a self-developed device to reproduce the wear evolution between the sealing pairs for magnetorheological damper. Experimental results show that higher surface roughness exhibits lower friction coefficient and better friction performance under MRF, especially in the absence of magnetic field. This is in stark contrast to the best wear resistance exhibited by polished samples under methyl silicone oil, a carrier fluid of MRF. This means that the effective coupling between surface roughness and iron particles helps to improve the friction and wear performance of sealing pairs. On this basis, the optimum surface roughness values of metal pin under MRF are obtained. Subsequently, the effect of pin surface morphology on the dynamics of iron particles are confirmed through the analysis of scanning electron microscopy images. It is further demonstrated that wear mechanism varies with surface roughness, that is, as the roughness increases, from sliding to mixing, and finally to rolling. Consequently, this research is of great significance for improving the wear resistance of sealing pairs under MRF.

CORAL: Quantitative Structure Retention Relationship (QSRR) of flavors and fragrances compounds studied on the stationary phase methyl silicone OV-101 column in gas chromatography using correlation intensity index and consensus modelling

The quantitative structure-retention relationship (QSRR) is a significant approach in chromatography and is used to predict the retention time of unknown compounds. In the present research article, the QSRR approach is employed to develop robust models of 1176 flavor and fragrance compounds on the OV-101 glass capillary gas chromatography column using a statistical parameter “correlation intensity index (CII)”. This CII parameter is featured in the most recent release of the CORAL programme (www.insilico.eu/coral). The optimal descriptor i.e. descriptor of correlation weight (DCW) computed by simplified molecular input-line entry system (SMILES) notation is employed to build QSRR models. Two target functions, TF1 (WCII=0) and TF2 (WCII=0.3) are applied to design 12 QSRR models from six splits using the balance of correlation strategy. The models created using CII are better in terms of statistical results. The numerical value of Rvalidation2=0.9561 of TF2Split1 is found to be considerably greater than that of the Rvalidation2 of the other splits of both target functions, hence, it is acknowledged as a leading model. The lists of structural attributes responsible for the changes in the retention index (RI) of flavors and fragrances compounds are also retrieved and discussed. Finally, a consensus model is built utilising the allocation structure of split 1 and the modified consensus (CM1) i.e. an average of predictions from all 'qualified' Individual models is found best model based on MAE (95%; test). The numerical value of the determination coefficient (R2) of the test set for the modified consensus (CM1) model is found 0.9772 which is higher than the leading Model.

Effects of Nanomaterials on Engineering Performance of a Potassium Methyl Siliconate–Based Sealer for Cementitious Composite

Effects of Nanomaterials on Engineering Performance of a Potassium Methyl Siliconate–Based Sealer for Cementitious Composite

Shaping of alumina microbeads by drop-casting of the photopolymerizable suspension into silicone oil and UV curing

The alumina microbeads were obtained by forming the drops of alumina suspensions in a silicone oil followed by UV curing. Due to the strong hydrophobic properties, silicon oil is a non-solvent (non-miscible) to the suspensions, thus the formation of perfectly rounded beads occurs spontaneously. The size of beads was controlled by a selection of a needle diameter and the position of needle tip: above or immersed in silicone oil. Thanks to that it was possible to obtain beads with diameters from 1000 to 1300 µm. The obtained alumina microbeads were characterized by quite a narrow size distribution, the differences in the size of the beads, within one series, did not exceed 1.5%. The research showed that the higher alumina volume fraction in suspensions favors the development of microstructure and thus influences mechanical properties. It was proved that the application of the methyl silicone oil as the environment responsible for the formation of the beads does not affect the sintering process.

Influence of different silicone oils on properties of MWCNTs-OH/PDMS coatings

ABSTRACT To research the influence of different silicone oil on the properties of the coatings based on polydimethylsiloxane (PDMS) reinforced by hydroxylated multi-walled carbon nanotubes, phenylmethyl silicone oil (PSO), methyl silicone oil (MSO), and the blend of PSO and MSO were incorporated into the antifouling coatings. The surface properties and leaching of silicone oil were investigated by water and diiodomethane contact angle and confocal laser scanning microscopy (CLSM). The mechanical properties were investigated by tensile test, and the antifouling properties were tested via bacterial biofilms and the diatom Navicula tenera adhesion. Results revealed that leaching rate, hydrophobicity, and surface free energy with coating with the blend of MSO and PSO (P/M-PDMS) was between those of the coating with PSO (PSO-PDMS) and coating with MSO (MSO-PDMS). P/M-PDMS was better than MSO-PDMS in resisting fouling organisms. P/M-PDMS prolonged the leaching process of the blend of MSO and PSO and showed better antifouling performance.

Effect of Methyl Silicone Oil to Moisture Resistance of Sodium Silicate Sands by Microwave Hardening

Effect of Methyl Silicone Oil to Moisture Resistance of Sodium Silicate Sands by Microwave Hardening

Controlling homogeneity of the first lithiation in methylated amorphous silicon

Methylated amorphous silicon (a-Si1-x(CH3)x:H) exhibits a longer life time as an anode material in Li-ion batteries as compared to pure amorphous silicon (a-Si:H). However, operando optical microscopy of thin-film electrodes shows that the first lithiation turns from spatially uniform to non-uniform by increasing the methyl content of the material. The non-uniform lithiation appears to result from an electrostatic instability related to the large resistivity of methylated amorphous silicon. Lithiation spots nucleate either instantaneously at the beginning of the lithiation through dielectric breakdown, or more progressively at morphological defects where the thickness of the layer is reduced. In both cases damage is generated by the high current density flowing through the locations at which lithiation spots nucleate. Boron doping of methylated amorphous silicon, which decreases the material resistivity, turns the lithiation of thin-film electrodes from inhomogeneous to homogeneous.

Influence of ultrasound on forming force in thin sheetmetal microforming using molten plastic as flexible punch

In this paper, a measuring force method was proposed for a special ultrasonic microforming method -- Micro Ultrasonic thin Sheetmetal Forming using molten plastic as flexible punch (short as Micro-USF), and the unique force change law in Micro-USF was observed. Using a flexible punch of the methyl silicone oil in the contrast experiment, the influence of ultrasound on the forming force in Micro-USF was investigated. The force transfer properties of the methyl silicone oil and molten EVA were analyzed (the molten EVA is a flexible punch used in Micro-USF). Experiment results showed that the ultrasound could significantly decrease the forming force in Micro-USF. Compared with the contrast experiment, the forming force in Micro-USF could be decreased by 74.7% and 91.0% respectively under the pre-pressure force of 196 N and 98 N when an arc-shape cross section microchannel with an opening width 755.1 μm and depth 247.8 μm was formed for an annealed copper sheet with a thickness of 30 μm.

Evaluation of Silicone Fluids and Resins as CO2 Thickeners for Enhanced Oil Recovery Using a Computational and Experimental Approach.

CO2 thickeners have the potential to be a game changer for enhanced oil recovery, carbon capture utilization and storage, and hydraulic fracturing. Thickener design is challenging due to polymers’ low solubility in supercritical CO2 (scCO2) and the difficulty of substantially increasing the viscosity of CO2. In this contribution, we present a framework to design CO2 soluble thickeners, combining calculations using a quantum mechanical solvation model with direct laboratory viscosity testing. The conductor-like polarizable continuum model for solvation free-energy calculations was used to determine functional silicone and silsesquioxane solubilities in scCO2. This method allowed for a fast and efficient identification of CO2-soluble compounds, revealing silsesquioxanes as more CO2-philic than linear polydimethylsiloxane (PDMS), the most efficient non-fluorinated thickener know to date. The rolling ball apparatus was used to measure the viscosity of scCO2 with both PDMS and silicone resins with added silica nanoparticles. Methyl silicone resins were found to be stable and fast to disperse in scCO2 while having a significant thickening effect. They have a larger effect on the solution viscosity than higher-molecular-weight PDMS and are able to thicken CO2 even at high temperatures. Silicone resins are thus shown to be promising scCO2 thickeners, exhibiting enhanced solubility and good rheological properties, while also having a moderate cost and being easily commercially attainable.

Thiolated Silicone Oils as New Components of Protective Creams in the Prevention of Skin Diseases.

This work investigates the possibility of using thiolated silicone oils as new components in protective creams and their impact on the efficacy of these products. Thiolated silicone oils were synthesized by amide bond formation between primary amino groups of poly17dimethylsiloxane-co-(3-aminopropyl)-methylsiloxane] and carboxylic groups of thiol ligand (3-mercaptopropionic acid) with carbodiimide as a coupling agent. To evaluate and compare the properties of these kinds of thiomers, three different emulsion o/w types were obtained. Emulsion E1 contained methyl silicone oil, E2 poly[dimethylsiloxane-co-(3-aminopropyl)-methylsiloxane], and E3 thiolated silicone oil (silicone-MPA), respectively. Physicochemical properties, including pH, conductivity, droplet size distribution, viscosity, and stability, were assessed. The efficacy of barrier creams in the prevention of occupational skin diseases depends on their mechanical and rheological properties. Thus, the method which imitates the spreadability conditions on the skin and how structure reconstruction takes places was performed. We also investigated textural profile, bioadhesion, protection against water and detergents, and water vapor permeability. Emulsion E3 was characterized by beneficial occlusion, spreadability, and adhesion properties. These features with prolonged residence time on the skin can make designed barrier creams more preferable for consumers.

The Compatibility of Three Silicone Oils with Polydimethylsiloxane and the Microstructure and Properties of Their Composite Coatings.

The compatibility of three types of silicone oil with polydimethylsiloxane, the phase separation of their mixture and the microstructure and properties of their composite coatings were investigated. The existing form of silicone oil in the coating and the precipitation behavior were also studied. The compatibility observed experimentally of the three silicone oils with PDMS is consistent with the results of the thermodynamic calculation. The silicone oil droplet produced by phase separation in the mixture solution can keep its shape in the cured coating, also affecting the microstructure and mechanical properties of the coating. It was found that methyl silicone oil and methyl fluoro silicone oil do not precipitate on the surface, and they have no effect on the surface properties of the coating. In contrast, phenyl silicone oil has obvious effect on the surface, which makes the water contact angle and diiodomethane contact angle of the coating decrease significantly.

Influence of organosilicon admixtures on the hydration of Portland cement

AbstractThe impact of three different organosilicon compounds: poly(dimethylsiloxane) (PDMS), potassium methylsiliconate (MESI) and triethoxyoctylsilane (OTES), used as integral admixtures, on Portland cement hydration has been investigated by isothermal calorimetry and DTA-TG analysis. The silicon-based compounds are widely used as internal hydrophobic agents added into batch water; therefore, their effectiveness was investigated by means of capillary water absorption test. The isothermal calorimetry was used to measure the rate and amount of heat released during ordinary Portland cement hydration with integral organosilicon admixtures at 20 °C, 30 °C, 40 °C and 50 °C. It allowed to determine the activation energy as well. The results indicate that used admixtures (except MESI admixture) decrease in the rate and amount of heat release during cement hydration. In addition, it is noticeable that the addition of MESI admixture significantly prolongs the induction period and delays hydration. In contrast to MESI and OTES admixtures, PDMS-based admixture does not affect significant on the activation energy. DTA-TG analysis had shown differences between reference sample and samples containing organosilicon admixtures during thermal decomposition, in terms of the amount of moisture and bound water, as well as Ca(OH)2or carbonates. The results presented in this paper enable a better understanding of the interactions between the organosilicon integral admixtures and the cement matrix. The study shows the effect of integral admixtures on cement hydration and thus the potential effect on the final properties of the cement-based material.

Elicitation of dopamine biosynthesis in common purslane as affected by methyl jasmonate and silicon

Common purslane that is a natural source of antioxidants, phenols, flavonoids, and dopamine possesses the potential to be used as a medicinal vegetable. The amount of active compounds in purslane is naturally low, so elicitation of plant response to produce more secondary metabolites may be important. In order to increase the amount of medicinal substances of the common purslane, foliar application and fertilization of silicon (each of them in two concentrations: 1 and 2 mM) alongside with methyl jasmonate spray (0, 75 and 150 µM) were applied. Measurement of silicon showed that the highest amount of leaf silicon was seen in 1 mM silicon spray regardless of methyl jasmonate treatments. Spraying of silicon without methyl jasmonate (Ss1M0) increased the leaf weight, grain yield, total phenol and leaf flavonoid content. Measurement of dopamine using high-performance liquid chromatography showed that fertilization of 1 mM silicon (Sf1M0) in the treatment group increased dopamine up to 2.5 folds in comparison with the control group. Also, silicon fertilization increased photosynthetic pigments and phosphorus concentration of leaves. To conclude, silicon can be used as an elicitor for increasing the amount of dopamine because its effect on dopamine biosynthesis was significantly more than methyl jasmonate that is a general elicitor. The effects of silicon on other medicinal substances of common purslane can be another avenue for further research.

Fog catcher brushes with environmental friendly slippery alumina micro-needle structured surface for efficient fog-harvesting

Water pollution has caused serious water shortage, and this trend becomes increasingly serious in the world. Therefore, how to efficiently access water resources is crucial for human beings. Considering the easy blockage problem of traditional fog-harvesting mesh, we used the fog catcher brushes structure to avoid the problem effectively. Besides, most of the modified coatings on fog-harvesting materials contain fluorosilane, which is expensive, harmful and unstable for a long time using. In addition to the general properties of dimethyl silicone oil, hydrogen methyl silicone oil can participate in a variety of chemical reactions and have a good film-forming performance due to its molecular structure containing active Si–H keys compared to the similar studies about the oil-infused coating. Besides, the low contact angle hysteresis of the droplet can benefit for the droplet sliding off the surface, which further improve the fog-harvesting efficiency. In this paper, mechanical cutting method, water bath method, and spray coating method were successfully combined to construct slippery “fog catcher brushes” with alumina micro-needle structured surfaces from micro control to macro design. Furthermore, the effect of wettability, pattern shape and pattern size on fog-harvesting performance were investigated. Experiment results indicated that slippery surface benefited for the fog deposition and transportation compared with the superhydrophilic and plain surface. When the fog droplets passed through the sample with 10-teeth arc-shaped pattern, it would fully contact the surface, and only a small amount of fog droplets escaped from the surface. With the adjacent droplets coalescing, the droplets slided off along both sides of the pattern, then the contact surface decreased gradually from the top to the bottom, so droplets could transport rapidly. Analysis demonstrated that the slippery arc-shaped fog catcher brushes with 10-teeth had a good effect on the capturing and transporting of fog droplets, which offered a way to rationally construct materials with enhanced fog-harvesting performance from micro control to macro design.

Effect of MgO sintering additive on mullite structures manufactured by fused deposition modeling (FDM) technology

An optimized recipe for 3D printing of Mullite-based structures was used to investigate the effect of MgO sintering additive on the processing stages and final ceramic properties. To achieve dense 3:2 mullite, ceramic filaments were prepared based on an alumina powder, a methyl silicone resin, EVA elastomeric binder and MgO powder. Using 1 wt% MgO and a dwell time of 5 h at 1600 °C, a dense mullite structure could be obtained from filaments with a diameter of 1.75 mm. Ceramic structures with and without sintering additive were printed in vertical and horizontal direction, to investigate the effect of printing direction on mechanical strength after sintering. Using four-point bending test, it was demonstrated that by using MgO, the printing orientation did not affect the mechanical strength significantly anymore. The low Weibull modulus could be explained by the closed porosity that emerge during the degassing of the preceramic polymer due to cross-linking.