Silyl Propyl Research Articles

Synthesis of Three Novel Silane-Based Carboxylic Acids for Application in Methacrylated Epoxy-Based Oligomers and Their Ability to Improve the Properties of UV Curable Hybrid Coatings

Improvement of thermal stability of silicone-based coatings was the main objective of this study. In this study bromoacetic acid (BAA) was reacted with 3-(mercaptopropyl) trimethoxy silane (MPTS) and trimethoxy silyl propyl thioacetic acid (TSTA) was produced. Also, bromoacetic acid (BAA) was reacted with 3-(triethoxysilyl) propylamine (APTS) and triethoxysilyl propylamino acetic acid (TSPA) was synthesized. Finally, from a reaction between trimellitic anhydride (TMA) and APTS, trimellitylimidopropyl triethoxysilane (TMIS) resulted. Compounds containing carboxylic acids and trimethyl silane were obtained in all of these reactions. Furthermore, hybrid coatings based on methacrylated bisphenol A epoxy (MBAE) and the synthesized carboxylic acids were obtained by photopolymerization. Polycarbonate substrates were utilized for preparation of the transparent hybrid films. Then the solvent resistance, hardness and gel content, as well as the adhesion of the coatings, were measured as physical and mechanical properties. According to the obtained results, these properties of the hybrid coatings were improved with the increase in alkoxysilanes and sol–gel precursor contents. The surface morphology was characterized by scanning electron microscopy (SEM). The results showed that silica particles were not dispersed homogenously at the molecular level in the hybrid system. Also, the thermogravimetric analysis results indicated that alkoxysilanes enhanced the thermal oxidative stability of the hybrid coatings.

Mechanical, thermo-mechanical and biodegradation behaviour of surface-silanized nettle fabric-reinforced poly(lactic acid) composites

This article focuses on silanisation of reinforcement surfaces to improvise reinforcement-matrix interfaces for developing nettle/PLA biocomposites with enhanced mechanical, thermo-mechanical, and biodegradation properties. Two different silane coupling agents, namely Tri-ethoxy silyl propyl methacrylate (TES-PM) and Amino propyl tri-ethoxy silane (APTES) are taken at different levels of concentration and grafted on the surface of cellulosic nettle reinforcement. The degree of silanisation is measured as an evidence of successful coupling reaction determining the morphological, structural, chemical and mechanical characteristics of the nettle woven reinforcement. It is shown that the interfacial strength of the biocomposite depends on the functional moiety and the level of concentration of the silane coupling agents. It is demonstrated that an appropriate silane coupling agent with an optimal level of concentration brings forth substantial improvement in the static mechanical (tensile, flexural and impact), dynamic mechanical (storage & loss moduli and damping factor) and biodegradation properties of nettle/PLA biocomposite without significant change in the thermal properties.

Efficient Removal of Pb(II) from Aqueous Medium Using Chemically Modified Silica Monolith.

The adsorptive removal of lead (II) from aqueous medium was carried out by chemically modified silica monolith particles. Porous silica monolith particles were prepared by the sol-gel method and their surface modification was carried out using trimethoxy silyl propyl urea (TSPU) to prepare inorganic–organic hybrid adsorbent. The resultant adsorbent was evaluated for the removal of lead (Pb) from aqueous medium. The effect of pH, adsorbent dose, metal ion concentration and adsorption time was determined. It was found that the optimum conditions for adsorption of lead (Pb) were pH 5, adsorbent dose of 0.4 g/L, Pb(II) ions concentration of 500 mg/L and adsorption time of 1 h. The adsorbent chemically modified SM was characterized by scanning electron microscopy (SEM), BET/BJH and thermo gravimetric analysis (TGA). The percent adsorption of Pb(II) onto chemically modified silica monolith particles was 98%. An isotherm study showed that the adsorption data of Pb(II) onto chemically modified SM was fully fitted with the Freundlich and Langmuir isotherm models. It was found from kinetic study that the adsorption of Pb(II) followed a pseudo second-order model. Moreover, thermodynamic study suggests that the adsorption of Pb(II) is spontaneous and exothermic. The adsorption capacity of chemically modified SM for Pb(II) ions was 792 mg/g which is quite high as compared to the traditional adsorbents. The adsorbent chemically modified SM was regenerated, used again three times for the adsorption of Pb(II) ions and it was found that the adsorption capacity of the regenerated adsorbent was only dropped by 7%. Due to high adsorption capacity chemically modified silica monolith particles could be used as an effective adsorbent for the removal of heavy metals from wastewater.

Silane treatment of drop-on glass-beads and their performance in two-component traffic paints

In this research, the surface of drop-on glass beads (GBs) was first etched, then modified using 3- trimethoxy silyl propyl methacrylate (MS) and trimethoxy vinyl silane (VS) through a sol-gel process to improve GBs’ adhesion to the two-component methyl methacrylate-based traffic paints (known as cold plastic paints). The etching was conducted in acidic, neutral, and basic conditions. Acidic etching condition was selected for the further experiments considering the highest number of OH groups provided by etching reaction on the surface of GBs. The FTIR and 13C-NMR spectroscopy were utilized to characterize chemical composition, and Atomic Force Microscopy (AFM) was used to evaluate the surface roughness / topography of the pretreated and silane-treated GBs. The amount of silane coated on the surface of the GBs was determined using thermogravimetric analysis (TGA). The dispersion of silane compounds on the surface of the treated GBs was assessed using Energy Dispersive X-Ray Analysis (EDXA). Neat and silane-treated GBs were then sprayed on freshly applied cold plastic paint samples using a designed lab spray device. Optical microscopy was used to evaluate the proper embedment depth of the GBs onto the surface of the paint samples. The abrasion test was performed in dry and wet conditions to evaluate the adhesion strength of neat and silane-treated GBs to the paint surface in normal and rainy weather. The coefficient of retroreflected luminance (RL) and the luminance coefficient under diffuse illumination (Qd) were measured to characterize the night and day retroreflective performance of cold plastic paints containing treated and untreated GBs. The abrasion test results showed the least weight loss in the paint markings containing drop-on VS-treated GBs (VS.GBs) in comparison to neat and MS-treated GBs (MS.GBs). This was assigned to increase in adhesion strength and interfacial interactions between VS.GBs and the polymeric matrix. The measured values of RL and Qd also confirmed the excellent maintenance of drop on VS.GBs on the surface of the two-component traffic paints.

Preparation and Characterization of Tris(trimethylsiloxy)silyl Modified Polyurethane Acrylates and Their Application in Textile Treatment.

Three series of silicone modified polyurethane acrylate (SPUA) prepolymers were prepared from dicyclohexylmethane-4, 4′-diisocyanate (HMDI), PPG1000, triethylene glycol (TEG), 2-hydroxyethyl acrylate (HEA), and multi-hydroxyalkyl silicone (MI-III) with tris(trimethylsiloxy)silyl propyl side groups. Their structures were confirmed by 1H NMR, 13C NMR, and Fourier transformed infrared (FTIR) analysis, and SPUA films were obtained by UV curing. The properties of films were investigated by attenuated total reflection (ATR)-FTIR, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), water contact angle (WCA), thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), water and hexane resistance, and tensile testing. The results showed that the structures and dosages of MI-III could influence the polymerization properties, surface properties, water and n-hexane resistance, and thermal and tensile properties of SPUA. For instance, the surface aggregation of tris(trimethylsiloxy)silyl propyl groups (even ~2.5 wt%) could endow SPUA films with less microphase separation, good hydrophobicity, lipophilicity, thermal stability, and mechanical properties. Interestingly, obvious regular winkles appeared on the surfaces of SPUAIII films, which are characterized by relatively high WCA values. However, relatively smooth were observed on the surfaces of SPUAIII films, which also exhibit lower water absorption ratio values. Furthermore, the ordinary cotton textiles would be transformed into hydrophobic and oleophilic textiles after treating with SPUA simply, and they were used in the oil/water separation study. Among them, consistent with water and hexane resistance analysis of SPUA films, SPUAII treated cotton textiles are characterized by relatively small liquid absorption capacity (LAC) values. Thus, phenyl groups and side-chain tris(trimethylsiloxy)silyl propyl groups are helpful to improve the hydrophobicity and lipophilicity of SPUA films. SPUAII-5 (even with 5 wt% MII) treated cotton textiles could efficiently separate the oil/water mixture, such as n-hexane, cyclohexane, or methylbenzene with water. Thus, this material has great potential in the application of hydrophobic treatment, oil/water separation, and industrial sewage emissions, among others.

Polyurethane with tris(trimethylsiloxy)silyl propyl as the side chains: Synthesis and properties

Two kinds of diols (MI and MII) and a triol (MIII) with tris(trimethylsiloxy)silyl propyl as the side chains were designed and synthesized. Then three series of silicone modified polyurethanes (SPUI-III) prepolymers were prepared from MI-III, polyether triol (N307) and dicyclohexylmethylmethane-4, 4′-diisocyanate (HMDI). Their structures were confirmed by 1H NMR, 13C NMR and FTIR analysis. Then SPUI-III films were obtained by the moisture curing of the polyurethanes prepolymers, and their properties were investigated by Attenuated total reflection flourier transformed infrared spectroscopy (ATR-FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), differential scanning calorimeter (DSC), water surface contact angle (WCA), water and ethanol absorption ratio, stress-strain, abrasion resistance and X-ray diffraction (XRD) analysis. It has been demonstrated that easier surface migration of side-chain silicone segments means only 10 wt% of MI-III can improve the surface hydrophobicity and smoothness, water resistance and abrasion resistance of SPU significantly. Meanwhile, the balance between the polar groups in the backbones and the nonpolar silicone oligomers in the side chains of MI-III is a key to control solubility, compatibility, migration and phase separation with polyurethane system. And difference in structures and dosages of MI-III can influence the abrasion resistance properties, microphase separation, thermal and tensile properties of the prepared SPU materials. Low loadings (10 wt%) of MI-III make remarkable abrasion resistance and excessive loadings make subdued abrasion resistance. Interestingly, the special microphase separation patterns could be obtained in SPUIII series with a proper MIII loading (10–20 wt %).

Study of mechanical properties of basalt fibers/epoxy composites containing silane-modified nanozirconia

Epoxy matrix composites owing to their outstanding properties such as high strength, low weight, high thermal stability and good stiffness are broadly utilized in various industries. Also, the basalt fibers as a green industrial material show various extraordinary properties such as high mechanical strength, desired stability, suitable chemical resistance, and high temperature resistance. In this study, the effect of silane-modified nanozirconia on the tensile and flexural properties of basalt fibers/epoxy composites is investigated. As a first step, the surface of nanozirconia was modified with a silane coupling agent namely 3-methoxysilyl propyl amine. Fourier transform infrared (FT-IR) spectroscopy has been used to demonstrate the chemical nature of the silanized ZrO2 nanoparticles prepared. 3-methoxy silyl propyl amine/nanozirconia with various loadings (0, 1, 3 and 5 wt.%) were added to the epoxy resin via mechanical and ultrasonication routes. The resultant mixtures were then utilized to fabricate ZrO2/satin texture basalt fibers/epoxy nanocomposites using hand-layup technique. This symptomatic behavior exposes the successful modified ZrO2 nanoparticles to enhance the interfacial bonding. Also, a scanning electron microscope (SEM) was used to study the distribution level of silanized ZrO2 nanoparticles in the matrix as well as the fracture surfaces of the specimens. Experimental results from three-point bending and tensile tests showed that with the dispersion of 3 wt.% nanozirconia, flexural strength, flexural modulus, flexural failure strain, tensile strength, tensile modulus and tensile failure strain enhanced by 90, 74, 84, 76, 85 and 14%, respectively, compared with specimens without nanozirconia. The SEM observations of the fracture surfaces of the nanocomposites clearly indicated that the enhancement in the flexural and tensile properties was due to the improvement in the interfacial adhesion between the basalt fibers and modified ZrO2 nanoparticles-enhanced epoxy matrix.

Clay Dispersed Styrene-co-3-Trimethoxy Silyl Propyl Methacrylate Impregnated Kumpang Wood Polymer Nanocomposites: Impact on Mechanical and Morphological Properties

In this study, the physical, mechanical, and morphological properties of clay dispersed styrene-co-3-trimethoxy silyl propyl methacrylate (ST-co-MSPM) impregnated wood polymer nanocomposite (WPNC) were investigated. The WPNC was characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), 3-point bending and free-vibration testing. The FT-IR results showed that the absorbance at 698 cm−1 was increased for ST-co-MSPM-clay-WPNC and ST-Clay-WPNC compared with other composites and raw wood. Besides, the hydroxyl group (-OH) was significantly reduced as the strong covalent bond was formed between the –OH groups of wood and the silyl propyl group of 3-trimethoxy silyl propyl methacrylate. The SEM results showed that ST-co-MSPM-clay-WPNC had a smoother surface compared to other nanocomposites and raw wood. The introduction of clay in the WPNC filled the void spaces of the wood and improved the intercalation between the wood and the polymer matrix. The modulus of elasticity (MOE), modulus of rupture (MOR), and dynamic Young's moduli (Ed) of WPNCs were considerably increased compare to wood polymer composites (WPCs) and raw wood. The raw wood exhibited a higher water uptake (WU) than WPNCs and WPCs.

Multicompartment micelles from silicone-based triphilic block copolymers

An amphiphilic linear ternary block copolymer was synthesised in three consecutive steps via reversible addition–fragmentation chain transfer polymerisation. Oligo(ethylene glycol) monomethyl ether acrylate was engaged as a hydrophilic building block, while benzyl acrylate and 3-tris(trimethylsiloxy)silyl propyl acrylate served as hydrophobic building blocks. The resulting “triphilic” copolymer consists thus of a hydrophilic (A) and two mutually incompatible “soft” hydrophobic blocks, namely, a lipophilic (B) and a silicone-based (C) block, with all blocks having glass transition temperatures well below 0 °C. The triphilic copolymer self-assembles into spherical multicompartment micellar aggregates in aqueous solution, where the two hydrophobic blocks undergo local phase separation into various ultrastructures as evidenced by cryogenic transmission electron microscopy. Thus, a silicone-based polymer block can replace the hitherto typically employed fluorocarbon-based hydrophobic blocks in triphilic block copolymers for inducing multicompartmentalisation.

Synergistic effect of nanoTiO2 and nanoclay on mechanical, flame retardancy, UV stability, and antibacterial properties of wood polymer composites

Wood–polymer nanocomposite (WPNC) based on styrene–acrylonitrile copolymer (SAN), γ-trimethoxy silyl propyl methacrylate-modified TiO2 nanoparticles, and nanoclay was prepared by impregnation. The flexural, tensile, and flame-retardant properties were improved. UV stability was evaluated by photo-induced weight loss, FTIR, loss in mechanical properties, and scanning electron microscopy. The results showed that UV stability was maximum for wood sample treated with SAN/TiO2 (0.5 %)/nanoclay (0.5 %). The presence of TiO2 nanoparticles in WPNC-exhibited antibacterial activity.

Effect of dangling chains on the structure and physical properties of a tightly crosslinked poly(ethylene glycol) network

Major imperfections in crosslinked polymers include loose or dangling chain ends that lower the crosslink density, thereby reducing elastic recovery and increasing the solvent swelling. These imperfections are hard to detect, quantify and control when the network is initiated by free radical reactions. As an alternative approach, the sol–gel synthesis of a model poly(ethylene glycol) (PEG-2000) network is described using controlled amounts of bis- and mono-triethoxy silyl propyl urethane PEG precursors to give silsesquioxane (SSQ, R–SiO1.5) structures as crosslink junctions with a controlled number of dangling chains. The effect of the number of dangling chains on the structure and connectivity of the dried SSQ networks has been determined by step-crystallization differential scanning calorimetry. The role that micelle formation plays in controlling the sol–gel PEG network connectivity has been studied by dynamic light scattering of the bis- and mono-triethoxy silyl precursors and the networks have been characterized by 29Si solid state NMR, sol fraction and swelling measurements. These show that the dangling chains will increase the mesh size and water uptake. Compared to other end-linked PEG hydrogels, the SSQ-crosslinked networks show a low sol fraction and high connectivity, which reduces solvent swelling, degree of crystallinity and the crystal transition temperature. The increased degree of freedom in segment movement on the addition of dangling chains in the SSQ-crosslinked network facilitates the packing process in crystallization of the dry network and, in the hydrogel, helps to accommodate more water molecules before reaching equilibrium.

Functionalized ormosil scaffolds processed by direct laser polymerization for application in tissue engineering

Synthesized N,N′-(methacryloyloxyethyl triehtoxy silyl propyl carbamoyl-oxyhexyl)-urea hybrid methacrylate was polymerized by direct laser polymerization using femtosecond laser pulses with the aim of using it for subsequent applications in tissue engineering. The as-obtained scaffolds were modified either by low pressure argon plasma treatment or by covering the structures with two different proteins (lysozyme, fibrinogen). For improved adhesion, the proteins were deposited by matrix assisted pulsed laser evaporation technique. The functionalized structures were tested in mouse fibroblasts culture and the cells morphology, proliferation, and attachment were analyzed.

Study on properties of simul wood (Bombax ceiba L.) impregnated with styrene acrylonitrile copolymer, TiO2, and nanoclay

Dimensional stability, thermal, and water repellency are very important properties of wood. In this research, wood polymer nanocomposite (WPNC) has been prepared by impregnation of styrene acrylonitrile copolymer (SAN), γ-trimethoxy silyl propyl methacrylate-modified TiO2 nanoparticles, nanoclay into simul (Bombex ceiba L.) wood. The characterization of the composites was done by using Fourier transform infrared spectroscopy, X-ray diffractometry, and thermogravimetry. The resultant WPNC exhibited an improvement in water repellency, moisture resistance, dimensional stability, chemical resistance, hardness, and thermal stability. The maximum improvement in all the properties has been observed for the wood sample treated with SAN/TiO2 (0.5 %)/nanoclay (0.5 %).

Effect of nano-SiO2 on properties of wood/polymer/clay nanocomposites

Wood polymer nanocomposites (WPNC) based on nano-SiO2 were prepared by impregnation of styrene acrylonitrile copolymer (SAN), SiO2 nanoparticles modified with γ-trimethoxy silyl propyl methacrylate (MSMA), and nanoclay into wood. The structure of modified SiO2 nanoparticles and WPNC was characterized by Fourier transform infrared spectroscopy (FTIR). XRD analysis showed the delaminated structure of SAN/SiO2/clay-treated wood composites. The synergistic effect of nano-SiO2 and nanoclay was investigated. Thermal stability of SiO2 nanoparticles decreased after modification, while that of wood treated with SAN, SiO2, and nanoclay improved. Morphological characteristics were examined by scanning electron microscopy (SEM). Mechanical properties, water uptake (%), dimensional stability, hardness, and flammability were found to improve due to incorporation of SiO2 and nanoclay into wood polymer composites. Maximum improvement in properties was observed in the wood polymer composites containing SiO2 and nanoclay at the ratio of 1:1.

Renewable Resource-Based Biocomposites of Various Surface Treated Banana Fiber and Poly Lactic Acid: Characterization and Biodegradability

Eco-friendly completely biodegradable biocomposites have been fabricated using polylactic acid (PLA) and banana fiber (BF) employing melt blending technique followed by compression moulding. BF’s were surface treated by NaOH and various silanes viz. 3-aminopropyltriethoxysilane and bis-(3-triethoxy silyl propyl) tetrasulfane (Si69) to improve the compatibility of the fibers within the matrix polymer. Characterization studies have been suggested that a better fiber matrix interaction because of the newly added functionalities on the BF surface as a result of chemical treatments. In comparison with the untreated BF biocomposite, an increase of 136% in tensile strength and 57% in impact strength has been observed for Si69 treated BF biocomposite. DSC thermograms of surface treated BF biocomposites revealed an increase in glass transition and melting transition due to the more restricted macromolecular movement as a result of better matrix fiber interaction. The thermal stability in the biocomposites also increased in case of biocomposite made up of BF treated with Si69. Viscoelastic measurements using DMA confirmed an increase of storage modulus and low damping values for the same biocomposite. Biodegradation studies of the biocomposites have been investigated in Burkholderia cepacia medium through morphological and weight loss studies.

Effect of surface treatments of banana fiber on mechanical, thermal, and biodegradability properties of PLA/banana fiber biocomposites

AbstractPoly lactic acid (PLA)/Banana fiber (BF) biocomposites were fabricated employing melt blending technique followed by compression molding. BF were surface‐treated by NaOH and various silanes viz. 3‐aminopropyltriethoxysilane (APS) and bis‐(3‐triethoxy silyl propyl) tetrasulfane (Si69) to improve the compatibility of the fibers within the matrix polymer. Mechanical tests revealed an increase of tensile strength to the tune 136% and impact strength to 49% as compared with the untreated biocomposite. Thermal properties of the composites have been evaluated using DSC and TGA. DSC thermograms revealed an increase in the melting transitions thus revealing effective fiber/matrix interface. The thermal stability in the biocomposites also increased in case of banana fiber treated with Si69. Viscoelastic measurements using DMA confirmed an increase of storage modulus and low damping values in the silane treated biocomposites. Biodegradation studies in the biocomposites have been investigated in B. cepacia medium through morphological and weight loss studies. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

Controlled Poly(ethylene glycol) Network Structures through Silsesquioxane Cross-Links Formed by Sol−Gel Reactions

A new type of poly(ethylene glycol) [PEG] hydrogel network was synthesized that is cross-linked through silsesquioxane domains [SiO1.5] formed by hydrolysis and condensation of a bis(triethoxy silyl propyl urethane)−PEG-2000 precursor. Step crystallization−DSC and DMTA techniques were used to characterize the PEG domains in the dry network while silsesquioxane cross-link structures and connectivity were determined by 29Si solid state NMR. No evidence was found by 29Si NMR or TEM for the formation of silica domains [SiO2]. The concentration of added acid in the sol−gel reaction controls the kinetics of the silsesquioxane formation and thus the size of these domains. Water-swelling studies confirm that when the particles are formed slowly (at lower acid concentration) there is an increase in the cross-link density and connectivity; i.e. the number of chains attached to each silsesquioxane domain. High connectivity also reduces the crystallinity of PEG in the dry network and results in a shift in both α- and α′-transitions to lower temperatures.

Methylene blue-encapsulated phosphonate-terminated silica nanoparticles for simultaneous in vivo imaging and photodynamic therapy

A bifunctional nanoparticles-based carrier for simultaneous in vivo imaging and photodynamic therapy by encapsulating methylene blue (MB) alone in the phosphonate-terminated silica matrix has been developed. The phosphonate-terminated silica nanoparticles, entrapping water-soluble photosensitizer MB (MB-encapsulated PSiNPs), are synthesized by the controlled synchronous hydrolysis of tetraethoxysilane and trihydroxyl silyl propyl methyl phosphonate in the water-in-oil microemulsion. The resulting MB-encapsulated PSiNPs effectively prevent the leakage of entrapped MB from the particles and provide protection for against reduction by diaphorase. Enough dose of irradiation to the MB-encapsulated PSiNPs under the light of 635 nm results in efficient generation of singlet oxygen and induces photodynamic damage to Hela cells. Furthermore, the non-invasive visualization of MB-encapsulated PSiNPs in mice under the in vivo imaging system confirmed the MB-encapsulated PSiNPs also presents near-infrared luminescence for in vivo imaging. And the effect of the PDT toward the xenograft tumor in vivo is exciting after imaging the MB-encapsulated PSiNPs injected tumor using in vivo optical imaging system. Thus, the single particle platform is effective for simultaneous in vivo imaging and photodynamic therapy without using extra agent, which can provide image-guidance for site-specific photodynamic therapy.

Examination of Sulfur-Functionalized, Copper-Doped Iron Nanoparticles for Vapor-Phase Mercury Capture in Entrained-Flow and Fixed-Bed Systems

The use of copper-doped Fe nanoaggregates silanized with organic sulfur as bis-(triethoxy silyl propyl)-tetra sulfide has been investigated for the capture of elemental mercury (Hg0) from the vapor phase for potential power plant applications. Silanization procedures resulted in 70% deposition of the targeted sulfur level, with particles containing approximately 4 wt % S. The addition of copper was found to increase the fixed-bed (total) capacity of this type of sorbent from 170 ± 20 μg Hg·g sorbent-1 with no copper doping to 2730 ± 80 μg Hg·g sorbent-1 at 1.2 wt % Cu. When no S is deposited, the capacity of Fe/Cu nanoaggregates was only 180 μg Hg·g sorbent-1. These findings suggest that a combined Cu−S mechanism is responsible for Hg capture. Moving-bed (injection) testing of the Fe-based sorbents in a simulated flue gas stream showed that the 1.2 wt % Cu sample was able to achieve significant removal of the Hg. At a modest sorbent injection rate of 3.6 × 10-3 g·L-1·h-1, this material showed a steady-state removal capacity of 107.5 μg Hg·g sorbent-1 for an inlet concentration of 17.8 μg·m-3. On the basis of only 4% usage of the total capacity during single-pass injection, it might be beneficial to develop methods to separate and recycle these materials to reduce power plant operation costs for Hg emissions control.

Poly-ether modified siloxanes as electrolyte additives for rechargeable lithium cells

Influence of four poly-ether modified siloxanes as electrolyte additives on charge–discharge cycling properties of lithium was examined. As siloxanes, diethylene glycol methyl-(3-dimethyl(trimethylsiloxy)silyl propyl)ether (sample A), diethylene glycol methyl-(3-dinethyl(trimethylsiloxy)silyl propyl)-2-methylpropyl ether (sample B), diethylene glycol methyl-(3-bis(trimethylsiloxy)silyl propyl)ether (sample C) and diethylene glycol-(3-methyl-bis(trimethylsiloxy)silyl-2-methylpropyl)ether (sample D) were investigated. As a base electrolyte solution, 1 M (M, mol L −1) LiPF 6-ethylene carbonate (EC)/methylethyl carbonate (MEC) (mixing volume ratio = 3:7) was used. As the anodes, lithium metal, natural graphite carbon and silicon–SiO 2–carbon (Si–C) composite electrodes were used. Lithium cycling efficiencies of these three anodes improved and an impedance of anode/electrolyte interface decreased by adding poly-ether modified siloxanes. Graphite/LiCoO 2 and Si–C/LiCoO 2 cells exhibited better anode utilization and good cycling performance by using 1 M LiPF 6–EC/MEC + siloxane electrolytes. It was also found that thermal stability of the electrolyte solutions improved by adding siloxanes. Thermal decomposition temperature of 1 M LiPF 6–EC/MEC shifted to higher temperature by adding siloxanes. Amount of heat-output of graphite–lithium anodes with M LiPF 6–EC/MEC electrolyte solutions decreased and the temperature starting the heat-output shifted to higher temperature by adding siloxanes. Among siloxanes examined here, samples B and D exhibited much better performance.