Polyaniline and polypyrrole prepared in the presence of surfactants: a comparative conductivity study

Polyaniline and polypyrrole have been prepared by chemical oxidative polymerization of the corresponding monomers in an aqueous medium containing an anionic surfactant—sodium bis(2-ethylhexyl) sulfosuccinate, dodecylbenzenesulfonic acid and its sodium salt, and sodium dodecyl sulfate. Determination of the yield, elemental composition and density proved, and FTIR spectroscopy confirmed, that the anionic surfactants become incorporated in the conducting polymers. The polymerizations in the presence of a cationic surfactant, tetradecyltrimethylammonium bromide, were carried out for comparison. While the conductivity of polypyrrole became enhanced after the introduction of an anionic surfactant, the changes in the conductivity of polyaniline were marginal. The conductivity changes in both polymers during thermal ageing were measured at 175 °C. The electrical stability of polyaniline was better than that of polypyrrole. The presence of a surfactant improved the stability of conductivity of polypyrrole but reduced the electrical stability of polyaniline.     

新型混合反胶团萃取溶菌酶的平衡行为

研究了由阴离子表面活性剂二-(2-乙基己基)琥珀酸酯磺酸钠(AOT)和非离子表面活性剂聚氧乙烯基(聚合度为4)壬基酚醚(OPE4)组成的一种新型混合反胶团体系及其萃取溶菌酶的平衡行为. 结果表明,该反胶团体系具有较大的含水量,且其含水量在较大的表面活性剂配比(0~0.8)范围内维持恒定,是由静电作用和胶束形态改变共同作用的结果. 无机盐种类和离子强度对上述混合反胶团的含水量有着显著的影响,继而影响到溶菌酶的萃取率. 它可归结为盐离子对扩散双电层和水化膜斥力的因素所致. 降低pH和提高总表面活性剂浓度均有利于溶菌酶的萃取.     

Characterization of polypyrrole films electrosynthesized onto titanium in the presence of sodium bis(2-ethylhexyl) sulfosuccinate (AOT)

Films of polypyrrole (PPy) were successfully electrosynthesized onto titanium in neutral and alkaline solutions of sodium bis(2-ethylhexyl) sulfosuccinate (Aerosol OT or AOT) by potentiodynamic, galvanostatic and potentiostatic techniques. Results of the characterization of the films by cyclic voltammetry, scanning electron microscopy (SEM) and adhesion measurements are presented. It was found that the AOT molecule remains entrapped within the polymer matrix. The initial growth of the polymer produces electroactive toroidal deposits whereas for electropolymerization of longer duration the typical globular structure is developed. Adherence to Ti increases with deposition time and this result is interpreted as a consequence of the growth of a composite PPy/Ti oxide.     

Novel route to pure and composite fibers of polypyrrole

An organic salt (FeAOT) is synthesized by the reaction of sodium 1,4‐bis(2‐ethylhexyl)sulfosuccinate (AOT) and ferric chloride. It is fabricated into fibers by manual drawing and electrospinning. Long polypyrrole (PPy) fibers are obtained for the first time by a vapor deposition reaction of pyrrole on the FeAOT fibers, and this technique is extended to the synthesis of PPy composite fibers with multiwalled carbon nanotubes (PPy–MWCNT fibers). The PPy and PPy–MWCNT fibers have a nanoporous morphology, a conductivity of 10–15 S cm^?1, and a tensile strength of 12–43 MPa. The electrochemistry and current–voltage characteristics of the PPy fibers are also studied. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1490–1494, 2007     

Partitioning of Polymeric Plutonium(IV) in Winsor II Microemulsion Systems

Abstract

The hydrolysis and polymerization of Pu(IV) can cause serious problems during the aqueous processing of spent fuel and nuclear wastes. Several studies describing the liquid/liquid extraction behavior of polymeric Pu(IV) have been reported in the literature. In many cases, poor plutonium extraction was accompanied by the appearance of an interfacial crud or third phase. Invariably, poor mass balances were observed during the extraction of aged, colloidal Pu(IV). Extraction of colloidal Pu(IV) by microemulsion-based solvent extraction systems, however, is capable of attaining bulk phase mass balances for Pu of 100%. The Winsor II microemulsions discussed in this paper consisted of sodium bis(2-ethylhexyl) sulfosuccinate in hexane with either octylphenyl-N,N-diisobutylcarbamoylmethyl-phosphine oxide or tributyl phosphate as coextractant. Backextraction of plutonium from microemulsion phases was achieved by Pu encapsulation in silica particles that were produced by the acid-catalyzed hydrolysis and polymerization of tetraethoxysilane within the aqueous microdroplets of the microemulsion.     

Inverse microemulsion polymerization of acrylamide in the presence of N,N-dimethylacrylamide

The presence of N,N-dimethylacrylamide (NDA) influences the stability of initial, clear, single-phase Winsor IV inverse microemulsion composed of toluene/AOT (sodium salt of bis(2-ethylhexyl) sulfosuccinate)/NDA/water/acrylamide (AAm). For a molar fraction of NDA, n_NDA = [NDA]/([NDA] + [AAm]) = 0.200 a single-phase system turned to a milky one during polymerization initiated by oil-soluble dibenzoyl peroxide or water-soluble ammonium peroxodisulfate, and finally a two-phase system was formed. For n_NDA values greater than 0.200 also the precipitation of a polymeric product was observed during polymerization. The (co)polymerization rate of AAm and NDA exponentially decreases with increasing value of n_NDA, while the reverse is true for the (co)polymer particle diameter. The results support the idea of simultaneously proceeding free-radical polymerization initiated by free radicals in continuous oil and dispersed water phase of the inverse microemulsion system.     

Conducting poly(styrene‐co‐divinylbenzene)/polypyrrole PolyHIPE composite foam prepared by chemical oxidative polymerization

Conducting poly(styrene‐co‐divinylbenzene)/polypyrrole (PPy) polyHIPE (polymerized high internal phase emulsion) composite foams were synthesized via chemical oxidative polymerization method. The effect of solvent and dopant type on the surface morphology and electrical conductivity of composite foams has been investigated. SEM micrographs showed that the morphology of PPy thin film on the internal surface of poly(styrene/divinylbenzene) (poly(St‐co‐DVB) polyHIPE support foam strongly depends on the solvent and dopant type used. Incorporation of dodecylbenzene solfunic acid‐sodium salt (DBSNa) as a dopant in chloroform solvent resulted in formation of a PPy thin film with higher molecular compact structure and electrical conductivity on the support foam as compared to other solvents and another dopant used. Fourier‐transform infrared spectroscopy was used to correlate the electrical conductivity of composite foams to their PPy structural parameters. As expected, the extended conjugation length of PPy in the presence of DBSNa dopant is the main reason for higher electrical conductivity of resultant composite foam. Electrical conductivity measurements revealed that the chemical aging of various conducting foams follows the first‐order kinetic model, which is a representative of a reaction‐controlled aging mechanism. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Enhancement of polyaniline properties by different polymerization temperatures in hydrazine detection

In this study, a simple and cost effective chemical sensor for hydrazine detection was developed using polyaniline (PAni). PAni was synthesized via chemical oxidative method at different polymerization temperatures (?10, ?5, 0, and 25°C) in the presence of sodium dioctyl sulfosuccinate (AOT) as dopant. The effect of polymerization temperature on the performance of the PAni sensor for hydrazine detection was evaluated. The sensor response was analyzed using UV–Vis spectrometer, where there is notable decrease in polaron peak at ～780 nm after the PAni was exposed to hydrazine. The reduction in the polaron peak is attributed to the decrease in the conductivity of PAni thin films owing to dedoping process by hydrazine. Fourier transform infrared analysis was carried out to study the intensity ratio of quinoid/benzenoid peak to identify the changes in chemical structure of PAni upon exposure to hydrazine. Besides that, all PAni sensors synthesized at different polymerization temperatures showed good reusability up to 10 cycles with respond and recovery time of 0.12 min and 0.08 min, respectively. Data collected in this study indicate that PAni which was synthesized at ?5°C could act as sensitive sensor for hydrazine detection with a detection limit of 0.24 ppm. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41746.     

Sulphur-polypyrrole composite positive electrode materials for rechargeable lithium batteries

A novel conducting sulphur-polypyrrole composite material was prepared by the chemical polymerization method with sodium p-toluenesulphonate as the dopant, 4-styrenesulphonic sodium salts as the surfactant, and FeCl₃ as the oxidant. The new material was characterized by Raman spectroscopy, thermogravimetric analysis, and scanning electron microscopy. Nanosize polypyrrole particles were uniformly coated onto the surface of the sulphur powder, which significantly improved the electrical conductivity, the capacity and the cycle durability in a lithium cell compared with the bare sulphur electrode.     

Polymerization inhibitors for polyunsaturated oils

Several edible anionic surfactants were found to function as polymerization inhibitors for safflower oil. The most effective additive was the sodium salt of phosphated mono- and diglycerides. Additional inhibitors included sodium diacetyltartaric acid esters of mono- and diglycerides, sodium stearoyl-2-lactylate, sodium stearyl fumarate, sodium succinoylated mono- and diglycerides, dioctyl sodium sulfosuccinate, and sodium sulfoacetate esters of mono- and diglycerides. It is suggested that these surfactants behave in a manner similar to methyl polysiloxane, as oxygen barriers at the oil-air interface. This view is supported by data showing that in the free acid, oil soluble form their functionality is minimal. But when they are neutralized to form the sodium salts their effectiveness is markedly enhanced. One of seven papers presented in the symposium “Biological Significance of Autoxidized and Polymerized Oils,” JOCS-AOCS Joint Meeting, Los Angeles, April 1972.     

Dopant-dependent variation in the distribution of polarons and bipolarons as charge-carriers in polypyrrole thin films synthesized by oxidative chemical polymerization

A study on the distribution of polarons vs. bipolarons as charge carriers in polypyrrole thin films doped with different dopant anions (chloride, p-toluenesulfonate and anthraquinone-2-sulfonate) is presented in this paper. The polypyrrole thin films synthesized by oxidative chemical polymerization have comparable thickness in the range of 80–100 nm. However, with the variation of the dopant anion, the conductivity of the polypyrrole thin films can differ by three orders of magnitude. The conductivity of polypyrrole thin films doped with chloride, p-toluenesulfonate and anthraquinone-2-sulfonate is 0.64 S/cm, 7.1 S/cm and 120 S/cm, respectively. The Raman spectroscopy and electron spin resonance (ESR) spectroscopy results show that (i) both polarons and bipolarons are present in the three types of polypyrrole thin films and (ii) the distribution of polarons vs. bipolarons as charge carriers in polypyrrole varies with the dopant anion used. The overall study reveals that the charge carriers in the anthraquinone-2-sulfonate-doped polypyrrole thin film are mainly spinless bipolarons, whereas the charge carriers in the chloride-doped polypyrrole thin film are dominated by paramagnetic polarons.     

Reversed Micellar Extraction of Vancomycin: Effect of pH,Salt Concentration,and Affinity Ligands

Abstract

Vancomycin was extracted from an aqueous feed solution into a reverse micellar solution of bis(2-ethylhexyl)sulfosuccinate sodium salt in isooctane. A low pH and salt concentration of aqueous feed solutions favors forward extraction. The backward extraction efficiency of vancomycin from reverse micelles into an aqueous phase, on the other hand, increases with pH. Affinity cosurfactants prepared by attaching a dipeptide d-alanyl-d-alanine or a racemic dipeptide dl-alanyl-dl-alanine to cholesteryl-chloroformate was employed for affinity reverse micellar extraction of vancomycin. The forward extraction efficiency increases significantly in the presence of an affinity cosurfactant. The recovery of vancomycin from fermentation broth with high selectivity was also achieved by employing this affinity cosurfactant.     

Electrically-assisted chemical vapor polymerization: A novel method for in situ polymerization of pyrrole

This article offers a fast and innovative process for carrying out in situ polymerization of pyrrole onto a polyester fabric. This process is based on electrically-assisted chemical vapor polymerization that takes around 180 s to produce an electroconductive fabric with a surface resistance of as low as 70 Ω. The ultrasonication carried out at 20 kHz frequency is quite effective in binding the polymer to the fabric. Fourier-transform infrared spectroscopy and X-ray diffraction studies confirm that the polymer formed is polypyrrole. The application of electric potential across an oxidant-enriched fabric results in polymer add-on of polypyrrole as high as 250%. The amount of polypyrrole formed and the surface resistance of the fabric are found to depend on the potential applied across the fabric. The concentrations of the oxidant and the dopant, the time of polymerization, and the rate of monomer vaporization are found to be critical in deciding the surface resistance of the fabric.     

表面活性剂与钕离子对金属表面化学镀镍磷的影响

采用紫外-可见分光光度计,研究了固定工艺条件下十二烷基二甲基甜菜碱(BS-12)与琥珀酸二(2-乙基己基)酯磺酸钠(SDOS)两种表面活性剂及钕离子对金属表面化学镀镍磷的影响,得到较佳的工艺条件:SDOS与BS-12摩尔比为1:1,Ni~(2+)与H_2PO_2-摩尔比为0.3,pH=8,70℃施镀并添加适量的硫酸钕.探讨了表面活性剂的作用机制.结果表明,在固定的基础镀液中加入SDOS与BS-12混合表面活性剂,镀液会产生明显的温度效应和很强的协同效应,其镀速的增加比相应的单一表面活性剂所产生的增幅要大;加入稀土金属钕离子后,镀速下降,但镀层质量得到改善.     

Ag/Co/Au三金属纳米粒子的合成及表征

反胶束是指由介于油和水界面的表面活性剂分子来稳定的,且均匀分散于连续油介质中的微液滴,由于微液滴的尺寸限制和其在油介质中的良好分散性,它可以作为"微反应器"合成纳米材料。以AOT为阴离子表面活性剂,采用反胶束法合成了Ag/Co/Au纳米粒子。采用紫外-可见(UV-Vis)吸收光谱、傅立叶红外光谱(FT-IR)对产物进行表征。研究结果表明,反胶束法合成Ag/Co/Au纳米粒子粒径均匀,分散性好、稳定性好。     

Gas mass transfer to AOT-based microemulsions

The present paper analyses the gas/liquid mass transfer process employing carbon dioxide as gas phase and ternary water in oil microemulsions as absorbent liquid phases. The liquid phases were obtained by a direct mixing of water, 2,2,4-trimethylpentane and sodium bis(2-ethylhexyl)sulfosuccinate (Aerosol OT). The characteristics of the microemulsions employed as liquid phase have been analysed to interpret the experimental results observed in the absorption process. More specifically, they have been analysed in relation to the percolation phenomenon and the effects produced by this phenomenon upon the different physical properties. Characteristic results have been observed for the gas/liquid mass transfer using microemulsions, because ternary microemulsions with high viscosity values in relation to pure water show a faster absorption process than the carbon dioxide/water system. This characteristic behaviour has been explained on the basis of the microemulsions internal dynamics.     

Conductive polypyrrole nanofibers via electrospinning: Electrical and morphological properties

Conductive polypyrrole nanofibers with diameters in the range of about 70-300 nm were obtained using electrospinning processes. The conductive nanofibers had well-defined morphology and physical stability. Two methods were employed. Electrospun nanofibers were prepared from a solution mixture of polypyrrole (PPy), and poly(ethylene oxide) (PEO) acted as a carrier in order to improve PPy processability. Both the electrical conductivity and the average diameter of PPy nanofibers can be controlled with the ratio of PPy/PEO content. In addition, pure (without carrier) polypyrrole nanofibers were also able to be formed by electrospinning organic solvent soluble polypyrrole, [(PPy3)⁺ (DEHS)⁻]_x, prepared using the functional doping agent di(2-ethylhexyl) sulfosuccinate sodium salt (NaDEHS) [Jang KS, Lee H, Moon B. Synth Met 2004;143:289-94. [24]]. Electrospun blends of sulfonic acid (SO₃H)-bearing water soluble polypyrrole, [PPy(SO₃H)-DEHS], with PEO acting as a carrier, are also reported. The factors that facilitate the formation of electrical conduction paths through the electrospun nanofiber segments are discussed.     

新的微乳液体系的状态方程

基于液滴变形模型,结合改进的Carnahan-Starling方程和适用于描述液滴吸引作用的Hamaker方程建立了一个微乳液体系的状态方程.运用所建立的状态方程研究了不带电微乳液体系的相平衡性质,并计算了十二烷基五氧乙烯醚-正癸烷-水体系O/W型微乳液渗透压以及二(2-乙基己基)磺酸基琥珀酸钠-正辛烷-水和二(2-乙基己基)磺酸基琥珀酸钠-正癸烷-水体系W/O型微乳液的液液相平衡,结果令人满意.     

Isotachophoretic analysis of surfactants

The qualitative and quantitative determination of anionic surfactants (sodium and lithium alkylsulfate, sodium dodecylbenzenesulfonate, sodium di-2-ethylhexyl sulfosuccinate, sodium and lithium perfluoroalkylcarboxylate, and lithium perfluorooctanesulfonate) were investigated by a capillary tube isotachophoresis using a potential gradient detector. The leading electrolyte solution was the mixture of acetonitrile and aqueous solution of histidine buffer containing calcium chloride. The terminating electrolyte solution was the aqueous solution of sodium octanoate. These electrolytes were effective for the analysis of the mixtures of strongly acidic surfactants.     

聚吡咯/凹凸棒石纳米复合材料的制备及导电性能

以三氯化铁(FeCl_3)为氧化剂,十二烷基磺酸钠(sodium dodecylsulfonate,DSNa)为掺杂剂,使吡咯单体(pyrrole,Py)在凹凸棒石(attapulgite,ATP)的表面发生原位聚合反应,制备出聚吡咯/凹凸棒石(polypyrrole/attapulgite,PPy/ATP)纳米导电复合材料.研究了毗咯用量、聚合温度、聚合时间、FeCl_3用量以及DSNa用量对纳米导电复合材料体积电阻率的影响,确定了制备纳米导电复合材料的工艺条件.通过X射线衍射、热重-差热分析、Fourier红外光谱、Raman光谱和透射电子显微镜对纳米复合材料进行表征,结果表明:当吡咯用量(以ATP的质量计)为30%,FeCl_3与Py的摩尔比为2.3,DSNa的浓度为0.02g/mL时,20℃反应3h得到的PPy/ATP复合材料的体积电阻率可达7Ω·cm,聚吡咯以非晶态形式存在于凹凸棒石表面,两者之间的作用为物理作用.