The determination of chlorinated biphenyls,chlorinated dibenzodioxins,and chlorinated dibenzofurans by GC-MS

High resolution gas chromatography, with mass selective detection, has been used for the analysis of PCB on methyl 50 % octyl polysiloxane (SB 50 Octyl), methyl octadecyl polysiloxane, and a smectic polysiloxane (SB Smectic); and for the analysis of polychlorodibenzodioxins and polychlorodibenzofurans with 1 to 8 chlorine substituents on 100 % cyanopropyl siloxane (SP 2331), smectic polysiloxane (SB Smectic), a new polar stationary phase (DB-Dioxin). The analysis has also been performed by column coupling.     

Improved Response and Steady State Times For Fibre Optical Sensors by Supported Liquid Membranes

ABSTRACT|Selectivity of fibre optical sensors can be improved by replacing the neat polymer cladding of optical fibres with a supported liquid membrane (SLM). In the present application the combination polysiloxane/perfluorokerosene was chosen as SLM. Halogenated hydrocarbons have been analysed. In addition to the enhanced selectivity over the conventional polysiloxane membrane, the response time of the SLM decreases more rapidly upon increasing analyte concentration, and its steady state time is reduced to 50% for all concentrations.

However, the SLM detection limit deteriorates by a factor of 2.     

Alkoxysilane functionalized polycaprolactone/polysiloxane modified epoxy resin through sol-gel process

Incorporating elastic polysiloxane and/or an inorganic silica network in epoxy resin could result in the enhancement of physico-chemical properties due to the existence of Si-O bonds. To improve the compatibility between polysiloxane and epoxy matrices and intensively strengthen the properties of the modified system, here polysiloxane was introduced into epoxy resin through compatibilizing epoxy-immiscible polysiloxane with epoxy-miscible polycaprolactone segments via a sol-gel process. To fulfill the process, a blend containing alkoxysilane-functionalized polycaprolactone/polydimethylsiloxane (PCS-2Si) was firstly synthesized using direct nucleophilic addition between -OH groups of polydiol and -NCO of a silane. And then a series of modified epoxy resins were prepared in different epoxy/PCS-2Si weight ratios. All the modified composites were characterized by conventional methods, and their morphological, thermal degradation and surface properties were studied. The results showed that increasing the PCS-2Si content caused the changes of miscibility between epoxy and polysiloxane. Also, the thermal stability of the modified composites was greatly improved. As for the temperature value at 5% weight loss, it reached to 308.5 °C for the composite containing 50-60% (wt%) PCS-2Si, over 150 °C higher than that for neat amine-cured epoxy resin. Similarly, the modified composites showed good hydrophobicity. The improvement of these properties came from the improved interaction between PCS-2Si and epoxy, the forming of Si-O-Si network and the enrichment of siloxane chains on the surface of films. Therefore, it is believed that this modified epoxy appears promising as new high performance and highly functional materials.     

亚微米级聚苯乙烯/聚硅氧烷核壳粒子的制备及其应用

以乳液聚合制备的聚苯乙烯乳液为种子,加入甲基三甲氧基硅烷(MTMS)水解溶液进行缩聚反应,合成亚微米级聚苯乙烯/聚硅氧烷核壳粒子,并以此作为光散射剂添加至聚甲基丙烯酸甲酯(PMMA)树脂中,制备了光散射材料;考察了亚微米级核壳粒子添加在PMMA树脂中的分散性。结果表明:经过双螺杆剪切作用的挤出加工后,可以实现核壳粒子在PMMA树脂中的良好分散。核壳粒子可以大幅度提高PMMA的雾度,当聚苯乙烯/聚硅氧烷核壳粒子(NS82)的含量为1%时,制得的PMMA样片(厚度为2 mm)的雾度为89%,透光率为69%,有效光散射系数为61%。     

Effect of polysiloxane and silane‐modified SiO2 on a novel intumescent flame retardant polypropylene system

The effects of polysiloxane and silane‐modified SiO₂ (M‐SiO₂) on properties of intumescent flame retardant polypropylene (IFR‐PP) have been studied. The results demonstrate that both polysiloxane and M‐SiO₂ could effectively enhance the flame retardancy of the IFR‐PP, despite only 20 wt% loading of IFRs. Remarkably, the polysiloxane can clearly improve the water resistance of IFR‐PP. It can obtain UL‐94 V‐0 rating, and its LOI remains over 34% after the water treatment. The surface tension data, XPS data, and SEM sufficiently prove that the some of polysiloxane transfers to the IFR‐PP surface during processing. The TGA data show that the polysiloxane more effectively enhances the thermal stability of the IFR‐PP at high temperature and increases the char residue. The CONE results reveal that the polysiloxane can clearly change the decomposition behavior of PP and markedly reduce flammability parameters. The homogenous and compact intumescent char layers further confirm that polysiloxane is a very effective silicon‐containing additive for the flame retardancy and water resistance of the IFR‐PP. Copyright © 2010 John Wiley & Sons, Ltd.     

Retention-index based vapor pressure estimation for polychlorobiphenyl (PCB) by gas chromatography

Summary Vapor pressures for 133 individual polychlorobiphenyl congeners as subcooled liquids were determined by two different approaches on the basis of gas-chromatographic retention indices obtained with two different non-polar stationary phases. The approach which is based on the retention indices obtained on a methyl-50% octyl polysiloxane phase (SB Octyl 50) and on reference vapor pressures of PCB congeners, and thus contains less approximations, should yield more accurate results than the method which uses retention indices obtained on a methyl polysiloxane phase (OV 101) and reference vapor pressure data taken from the n-alkanes of the retention index system. A systematic deviation is observed between the values obtained by the two different methods. The first method gives constantly slightly higher values for the vapor pressure. This will be caused by the different separation characteristics of the two non-polar stationary phases used, as well as by uncertainties in the reference data for the vapor pressure calculations.     

以衍生化聚硅氧烷为固定相的开管毛细管电色谱柱的研制

建立了一种简单可行的制备衍生化聚硅氧烷开管毛细管电色谱柱的方法,石英毛细管无需浸蚀,直接键合上大分子的聚硅氧烷,用异丁烯酸丁酯和乙烯基磺酸衍生化时对苯的同系物有很好的分离能力,对甲苯柱效可达1.52×10⁵N/m(N为理论塔板数),柱效稳定;当用烯丙基全甲基β-环糊精和乙烯基磺酸衍生化时,石英毛细管先经溶胶-凝胶处理后,所制得的柱子对萘普生对映体的分离度可达0.81.     

Comprehensive two-dimensional gas chromatography using a high-temperature phosphonium ionic liquid column

A high-temperature ionic liquid, trihexyl(tetradecyl)phosphonium bis(trifluoromethane)sulfonamide, was used as the primary column stationary phase for comprehensive two-dimensional gas chromatography (GC × GC). The ionic liquid (IL) column was coupled to a 5% diphenyl/95% dimethyl polysiloxane (HP-5) secondary column. The retention characteristics of the IL column were compared to polyethylene glycol (DB-Wax) and 50% phenyl/50% methyl polysiloxane (HP-50+). A series of homologous compounds that included hydrocarbons, oxygenated organics, and halogenated alkanes were analyzed with each column combination. This comparison showed that the ionic liquid is less polar than DB-Wax but more polar than HP-50+. The most unique feature of the IL × HP-5 column combination is that alkanes, cyclic alkanes, and alkenes eluted in a narrow band in the GC × GC chromatogram; whereas, these compounds occupied a much larger portion of the DB-Wax × HP-5 and the HP-50+ × HP-5 chromatograms. Each column combination was used to analyze diesel fuel. The IL × HP-5 chromatogram displayed narrow bands for three major compound classes in diesel fuel: saturates, monoaromatics, and diaromatics. The IL column was used at temperatures as high as 290 °C for several months without any noticeable changes in column performance.     

Preconcentration using diethylenetriaminetetraacetic acid-functionalized polysiloxane (DETAP) for determination of molybdenum(VI) in seawater by ICP–OES

This paper reports a new method for preconcentration and separation of trace amounts of molybdenum in seawater samples prior to determination by inductively coupled plasma–atomic emission spectroscopy (ICP–OES). Diethylenetriaminetetraacetic acid-functionalized polysiloxane (DETAP) was synthesized by carboxymethylation of amino groups on triamine immobilized polymer, which was prepared by modification of 3-chloropropylpolysiloxane with diethylenetriamine. The resulting polysiloxane is highly selective and efficient in chelating Mo(VI) at trace levels. It can be used as a column packing material. The polysiloxane column can be reused over ten times without losing its original properties, so it is suitable for preconcentration of molybdenum species in seawater samples before determination. The parameters governing the characteristics of polysiloxane for adsorption of Mo(VI) were investigated. These include the effect of pH, amount of polysiloxane, equilibrium time, adsorption isotherm, maximum adsorption capacity, interfering ions, flow rate, capacity for reuse, and desorption. The precision of the preconcentration method, calculated as the relative standard deviation of seawater samples, was 3%. The preconcentration factor was 100. The detection limit, defined as 3 times the standard deviation of five replicate measurements of the blank sample at pH 3, was 0.17 g L^–1. Measurement results for standard reference materials were in good agreement with the certified values [(CRMs), NASS-2 Seawater (Open Ocean) and CASS-2 Seawater (Coastal)].     

Synthesis and physicochemical properties of polysiloxane functionalized with aminoacetic acid groups

Polysiloxane functionalized with aminoacetic acid groups was synthesized using sol–gel technology. Elemental analysis and FTIR spectroscopy were used to determine the composition of the polysiloxane show that it is a mesoporous material with a developed surface (109.4 m2/g). It was found that the selective properties of carboxymethylated polysiloxane towards transition metal ions simultaneously present in an ammonium acetate solution change in the order Zn < Cu > Ni > Co > Pb > Cd. It was shown that the sorption of copper(II) ions by carboxymethylated aminopropylpolysiloxane with particle sizes of 50–71 μm reaches its maximum level within 2 h; the rate-limiting step of the process is the chemical reaction between the ions and the polysiloxane functional groups; and the pseudo-second-order model is the best way of describing sorption.     

Synthesis of copolymer electrolytes based on polysiloxane and their high temperature durability analysis for solvent-free dye-sensitized solar cells

The present work develops a new type of solvent-free copolymer electrolyte based on polysiloxane for dye-sensitized solar cells (DSSCs). The electrolyte is characterized by conductivity measurements, hydrogen-1 nuclear magnetic resonance spectroscopy, rheology, and DSSC performance. Repeated units of the ethylene oxide on methylhydrosiloxane show plasticizing effects and enhanced durability of the DSSCs. DSSC employing the polysiloxane electrolytes show no energy conversion efficiency decay after 16 days test at room temperature and yields a conversion efficiency of 1.5% during long-term stability measurement at 90 °C under white light irradiation of 100 mW cm⁻². The new solvent-free polysiloxane copolymer electrolyte can be good candidate for next generation DSSC.     

Modification and Dispersion of the Polysiloxane Materials with Perfluorocarbon Groups and Cationic Side Chains

Novel polysiloxane material modified with perfluorocarbon groups and quaternary cationic side chains was synthesized by ring-opening polymerization of cyclosiloxane and graft reaction. The polysiloxane polymers containing pendant groups were the polysiloxanes modified with amino group, perfluorocarbon side chain, tertiary and perfluorocarbon side chains, or quaternary cationic and perfluorocarbon groups. The yields of the modified polymers were 94.2%, 86.7%, 88.4%, 82.5%, respectively. FTIR, ¹H NMR, ¹³C NMR, and ¹⁹F NMR were used to characterize the structures of the polysiloxane materials. The dispersion technology of the polysiloxane materials was investigated. The polysiloxane material modified with perfluorocarbon and cationic groups imparted high surface activity. The polyesters treated with the polymers had good repellency to water.     

含氢聚硅氧烷含氢量的红外光谱测定研究

本文利用含氢聚硅氧烷中的Si-H键在2 172 cm~(-1)处的吸收峰,选择四甲基四氢环四硅氧烷作为模型化合物,用偏最小二乘法建立了红外光谱法测定含氢聚硅氧烷中含氢量的方法,其有效测量范围为0.0043～0.5365 mg/mL,回收率在91%～106%之间.     

Solvation enthalpies and heat capacities of n-alkanes in four polymer phases by capillary gas chromatography

Molar solvation enthalpy (deltasol H(o)298) and molar heat capacity changes (deltasol C(o)p) were determined by gas chromatography for the C6-C12 n-alkanes on four preferred stationary phases (100% polydimethyl siloxane, 50% diphenyl-50% dimethyl polysiloxane, 50% trifluoropropyl methylsiloxane, and polyethylene glycol) in commercial FSOT. Statistical evaluation indicated the temperature independence of deltasol C(o)p in the range 303-393 K. Deltasol H(o)298 depends linearly on the number of carbon atoms in the n-alkanes, but no linearity could be established for deltasol C(o)p of higher homologues on polar columns, which may be due to a more ordered state on the liquid phase. The homologues for which a linear temperature dependence exists demonstrated that deltasol C(o)p is related linearly to the van der Waals volume and the temperature derivative of the density of the stationary phase. The results are consistent with a simple physical explanation at the molecular level.     

Synthesis and surface properties of PDMS–acrylate emulsion with gemini surfactant as co-emulsifier

Composite latex particles of acrylate and polydimethylsiloxane (PDMS) with high PDMS content was prepared by emulsion copolymerization and characterized by particle size analyzer, X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR). With gemini surfactant as the co-emulsifier in the system, the PDMS content in the system reached 50%, which was far higher than the other reported values. Through the characterization of the particle size analyzer, the particle size augmented with the increase of the amount of PDMS, which could be said that the polysiloxane had participated into the reaction and had been introduced into the colloid particle. The results of FTIR indicated that almost all the monomer had been exhausted in the reaction because there was no C=C and D₄ characteristic peaks in the spectrum. Besides the surface properties also were measured by surface tension analysis, water absorption, and the static contact angle, it could be found that with the increase of polysiloxane content, the excellent properties acquired by PDMS were clearly revealed by the findings, such as the decrease of surface tension and water absorption, and the increase of static contact angle. All the measurements were consistent with the conclusion that the composite latex particles of polysiloxane and acrylate with high siloxane content had been prepared successfully.     

ZSM-5表面酸性的CLD改性及其对择形催化性能的影响

为了获得分子筛催化反应中所需产物的高择形催化选择性,往往必须消除分子筛外表面酸性和减少孔道开口尺寸.目前,各种改性方法已被用于提高ZSM-5的选择性,例如金属、非金属化合物的浸渍,化学气相硅沉积(SiO2-CVD)和预结焦处理等1.虽然采用大分子有机物可以消除分子筛外表面的酸性位,但这种改性在反应条件下尤其在高的反应温度下是不稳定的2.……     

Polysiloxane network formation observed by time-resolved small-angle X-ray scattering

Time-resolved small-angle X-ray scattering was observed on systems undergoing gelation. A polysiloxane network was used as a model system, where the polysiloxane network was formed by hydrosylation of VT-M with F4-C. The Flory-Stockmayer model for gelation was found to be satisfactory to describe the polysiloxane network formation. No inhomogeneous distribution of densely crosslinked region exists, and in this respect the gel formed by the polysiloxane network is homogeneous. The invariance of the correlation length ξ evaluated from the Lorenzian term suggests that the local network architecture would not change by gelation.     

一种新型主链杯芳冠醚聚硅氧烷毛细管气相色谱固定相(英文)

选用特殊的硅氢加成试剂（ＣＨ３）２ＳｉＨＣｌ，首次合成了一种杯芳冠醚单元位于聚硅氧烷主链的新型毛细管气相色谱固定相（Ｍ－Ｃ［４］Ｃ－５ＰＳＯ）。新型固定相具有很好的热稳定性，并对酚类、硝基及氯取代类芳香族位置异构体有良好的分离。其进一步的应用及分离机理有待于深入研究。     

Properties of ABA and BA polysiloxane amphiphiles modified by polyether

To investigate the effect of content of polyether (F400) grafted on the properties of polysiloxane amphiphiles, polyether was grafted on the polysiloxane by hydrosilylation reaction with H₂PtCl₆ catalyst. The modified polysiloxanes were divided into two types; moreover, the ratio of polyether and polysiloxane was 1:1 or 1:2. The first one was similar to the conventional surfactant structure that is BA polysiloxane amphiphile, which own one hydrophobic chain and one hydrophilic group. Another one was ABA polysiloxane amphiphile, which possess one hydrophobic chain and two hydrophilic groups at the terminal. In our work, we compared the property of modified polysiloxanes with various contents of polyether in aqueous solution at room temperature to analyze the impact of polyether content on siloxane surfactants. The conclusion was that siloxane amphiphiles possess good solubility, high surface activity, and excellent spreading property.