Lithium surface protection by polyacetylene in situ polymerization

Direct acetylene polymerization at ambient temperature on a Li metal surface and polyolefin separator with Ziegler–Natta catalyst was developed. Thin conducting polyacetylene films with strong adhesion to Li or polyolefin surface was formed and studied by electrochemical methods. AC impedance measurements and charge/discharge tests were applied for prepared coin cells with LiCoO₂ as a cathode material in the presence of 1 M LiPF₆ in dimethyl carbonate, ethylene carbonate, propylene carbonate (5:3:2 vol) electrolyte. Three kinds of polyolefins were used to prepare composite separators with polyacetylene: polypropylene (PP), polyethylene (PE) and three-layer type: PP–PE–PP.The polyacetylene film thickness on Li metal or polyolefin separator was easily controlled by catalyst concentration and polymerization time. It was shown that high ionic conductivity (7.5 × 10⁻⁵ S cm⁻¹) might be achieved due to higher porosity of a polyethylene separator. Li–polyacetylene electrodes showed highest ionic conductivity and stability in charge/discharge tests.     

光催化剂载体— — —羧基氟碳共聚物纤维膜的制备及耐光降解性能研究

以甲基丙烯酸十二氟庚酯(DHFMA)和甲基丙烯酸(MAA)为单体,通过溶液聚合制备出MAA含量不同的羧基氟碳共聚物(DHFMA-co-MAA),并通过静电纺丝装置制备了羧基氟碳共聚物纤维膜。研究了MAA含量和溶剂对纤维膜形貌的影响,分析了纤维膜的耐光降解性能,结果表明:MAA含量25%的DHFMA-co-MAA以DMF作为纺丝溶剂,MAA含量10%的DHFMA-co-MAA以丁酮+DMF(质量比为2∶8)作为纺丝溶剂,均可以制备出表面平滑、纤维直径较小、形态均一的纤维膜;MAA含量10%的DHFMA-co-MAA纤维膜的光稳定性能更好,更适合用作光催化剂载体。     

Polyene films prepared by poly(ethylene glycol)s-catalyzed dehydrochlorination of poly(vinyl chloride): chemical and electrochemical properties

Poly(vinyl chloride) (PVC) film containing certain amounts of poly(ethylene glycol)s (PEG) catalyst can be extensively dehydrochlorinated by aqueous potassium hydroxide. The molar mass of the PEG used as phase transfer catalyst is ranged from 200 to 800 g mol⁻¹. According to the results of elemental analysis and UV–visible, Fourier transform-infrared (FT-IR) and FT-Raman spectra, the polyene films obtained from these systems are polyacetylene-like and contain relatively long conjugated sequences. The highest conversion of the reaction at room temperature is measured to be about 90% (f_H). The conductivity of iodine-doped polyene films can reach to the order of 10⁻² S cm⁻¹. The electrochemical doping process of dehydrochlorinated PVC film is controlled by diffusion mechanism like polyacetylene, and some irreversible degradation at the polyene surface occurs when the potential is rising above 1.6 V.     

Condensed phase route to polyacetylene

We present a versatile and convenient route to polyacetylene--the condensed phase metathesis polymerization of 1,3,5,7-cyclooctatetraene (COT). Dissolution of catalyst in “neat” cyclooctatetraene provides a means of transforming the liquid into a highly lustrous film at ambient temperature and pressure.New processing modes and novel morphologies (as observed by electron microscopy) have been found. The mechanism of polymerization, and its effect upon the stereochemical structure of the resulting polyacetylene, is discussed.Poly-COT films are shown to have physical and spectral properties very similar to polyacetylene prepared by the Shirakawa methodology. Iodine-doped films have conductivities greater than 300 ohm⁻¹/cm. Bromo-cyclooctatetraene has been polymerized to a strong, flexible golden film. The film is swollen in THF to a blue-black material; upon removal of the THF solvent the polymer shrinks to a golden film.     

Synthesis of highly-oriented polyacetylene film in a liquid crystal solvent

The synthesis of oriented polyacetylene films is investigated by using a nematic liquid crystal as polymerization solvent. Highly-oriented thin films are obtained under a flow of catalyst solution in which a nematic liquid crystal is used instead of common solvents such as hexane and toluene. Nematic liquid crystals that could be used as solvents for the Ziegler-Natta catalysts are limited due to their reactive substituents with the active species and/or the components of the catalyst. Among the available nematic liquid crystals, phenylcyclohexane type is stable in the presence of Ziegler-Natta catalysts. Since fibril alignment in the oriented films is found to be along the flow direction of the catalyst solution, it appears that the direction of fibril growth coincides with that of the liquid crystal orientation, which is caused by an alignment effect of the liquid crystal molecules under a flow of the solution.This new and simple method allows quite large highly-oriented films to be synthesized, which makes it possible to investigate various kinds of anisotropic properties of polyacetylene.     

注多元热流体环境下流速对N80钢腐蚀行为的影响研究

目的 研究不同流速条件下N80钢在注多元热流体环境中的腐蚀特征,探究流速变化对N80钢腐蚀行为的影响规律及机理。方法 利用自制高温高压多相流冲刷腐蚀环路装置模拟不同流速(0、0.5、1.0、2.0 m/s)的注多元热流体环境,采用失重法计算不同流速下N80钢的平均腐蚀速率,并同时进行原位电化学测试。采用扫描电子显微镜(SEM)和X射线衍射仪(XRD)对不同流速条件下N80钢腐蚀后的腐蚀产物物相组成和表面微观形貌进行分析。结果 N80钢在注多元热流体环境中的平均腐蚀速率随着流速增加而增大。流速增加影响O2的扩散传质过程、近表面离子分布和壁面剪切力的大小,使腐蚀产物膜特征发生变化。0 m/s时,腐蚀产物主要由FeCO3和少量Fe2O3组成,为单层膜结构,腐蚀形态为均匀腐蚀。0.5~2.0 m/s范围内,腐蚀产物种类增加,主要由FeCO3、Fe2O3和少量FeO(OH)组成,呈双层膜结构,同时N80钢表面腐蚀产物膜出现鼓泡,且随流速增加鼓泡数量增加,去除腐蚀产物膜后发现鼓泡下方存在局部腐蚀。原位电化学测试结果表明:随着流速增加,塔菲尔极化曲线的阳极斜率增大,阴极斜率减小。电化学阻抗谱测试结果表明,N80钢表面外层腐蚀产物膜电阻Rf1、电荷转移电阻Rct和扩散电阻W随流速增加而减小。结论 流速增大加快了O2的扩散传质过程,使得腐蚀电化学控制步骤由阴极氧扩散过程转变为阳极溶解过程,且试样表面保护性FeCO3膜厚度减小,导致产物膜保护性降低。另外,Fe²⁺更容易被氧化形成Fe³⁺,局部FeCO3被氧化成为Fe2O3,破坏了内层膜的完整性,导致局部腐蚀发生。     

Structure,morphology and techniques of chemical modification of polyacetylene (CH)x

In order to obtain soluble or more characterizable products, the copolymerization of acetylene with 1-alkynes and the chain transfer reaction with hydrogen were studied. The influence of different catalyst systems on structure and morphology of polyacetylene was investigated. It was found that no catalyst presently available is able to produce simple morphologies. From structural and morphological studies it is concluded that polyacetylene is partially crystalline with no detectable preferential chain orientation and is possibly moderately crosslinked.     

Micropatterning of liquid crystalline polyacetylene derivative by using self-organization processes

Side-chain type liquid crystalline polyacetylene, which has mesogenic moieties as side chains, is one of the promising materials for practical applications in the electronics. Micropatterning of the conductive polymer is a significant issue in this field. We show a simple method to fabricate micropatterns of side-chain type liquid crystalline polyacetylene derivative. Under dry condition, stripes patterns and lattice pattern were formed based on the fingering instability and stick-slip motion of the receding meniscus. Honeycomb-patterned polymer film was obtained by casting polymer solution under humid condition. The micropatterns drastically changed by changing solution concentration and preparation conditions.     

Mechanistic studies of the electropolymerization of 2,2′-bithiophene and of pyrrole to form conducting polymers

The electropolymerizations of 2,2′-bithiophene and of pyrrole to form conducting polymers were investigated by several electrochemical methods. Cyclic voltammetry indicates that a peak at 1.1 V is associated with the polymer and that the same product is formed from thiophene as from 2,2′-bithiophene. The rate of polymer formation has a zero kinetic order dependence on monomer concentration for polymerization of pyrrole or 2,2′-bithiophene. A dependence on concentration of supporting electrolyte is interpreted as a consequence of anion diffusion and oxidative doping in the polymer. The kinetic results are consistent with an oxidative coupling mechanism for polymer formation. The electrochromic switching of the polymer film was investigated by spectroelectrochemical methods and the kinetics were examined over a range of film thicknesses.     

Electrochemical polymerization of acetylene with copper catalyst on platinum and copper electrodes

Acetylene was electrochemically polymerized cathodically at −0.60 V (versus Ag/AgCl) in the presence of copper(I)perchlorate catalyst in acetonitrile containing tetrabutylammonium perchlorate (TBAP) at room temperature under nitrogen atmosphere. An insoluble, black film was deposited on platinum (Pt) and copper (Cu) working electrodes. The dry electrical conductivity of the fresh film was about 550 S cm⁻¹. The chemical structure of the product was investigated by cyclic voltammetry, infrared spectroscopy (IR) and atomic absorption spectroscopy (AAS). Based on the IR data the product consists of a cis-rich form of polyacetylene.     

磷化处理对无铬钝化热镀锌板耐蚀性能的影响

研究了磷化处理工艺对无铬钝化热镀锌板耐腐蚀性能和表面形貌的影响。采用扫描电镜对其表面形貌进行分析，同时与未经过磷化处理的钝化板表面形貌进行对比；采用电化学阳极极化曲线方法和电化学阻抗法对磷化处理后钝化板的耐腐蚀性能进行了研究。在钝化板膜重为0.8 g/m²的情况下，经磷化处理的钝化板表面钝化膜完好，没有发现锈蚀或钝化膜剥落现象；经磷化处理的钝化板自腐蚀电位和阳极电流密度不变，阴极电流密度和自腐蚀电流密度有所提高；Nyquist图的高频部分在磷化处理前为容抗弧，磷化处理后出现具有Warburg阻抗的直线，说明磷化处理后钝化膜表面出现扩散过程。 研究表明，钝化板经过磷化处理后表面未形成磷化膜，耐腐蚀性能仍来自原钝化膜，经磷化处理的钝化板的耐腐蚀性能有所降低。因此，现有常规的磷化处理并没有增加钝化板的耐腐蚀性能，如果有需要提高钝化板耐腐蚀性能的要求，必须针对无铬钝化板研制专用的磷化液和磷化工艺。     

Quantitative optical study of I2-doped polyacetylene

The relation between dopant concentration and adsorption spectra of iodine-doped polyacetylene films is studied quantitatively with films whose iodine contents are analysed by radioactivation analysis. It is shown that the dopant content of thin polyacetylene film can be estimated from the absorption spectra. For heavily iodine-doped film, optical constants are determined from measured infrared, visible and ultraviolet spectra by the aid of the Kramers–Kronig relation. The absorption coefficient of 64% iodine-doped film at the absorption maximum of the mid-gap band, 7500 cm⁻¹, is 2.5 × 10⁵ cm⁻¹ and that of the same film at the adsorption maximum of the pentaiodide ion, 19 000 cm⁻¹, is 2.9 × 10⁵ cm⁻¹, whereas the maximum value for undoped film at 18 500 cm⁻¹ is 1.5 × 10⁵ cm⁻¹ (cis-rich form).     

Morphology and structure of highly oriented polyacetylene

Highly oriented polyacetylene films have been synthesized under high magnetic field (20 KG; 47 KG); using as solvent of the catalyst the nematic phase of a liquid crystal. We report here on morphology of undoped and iodine doped samples studied by transmission electron microscopy (T.E.M.) and electron diffraction (E.D.). Results about orientation, crystalline order, crystallite size are reduced.     

LY12铝合金/钝化膜/环氧涂层复合电极的腐蚀电化学行为

通过电化学阻抗谱（EIS）技术研究了LY12铝合金／钝化膜／环氧涂层复合电极在NaCl水溶液中的腐蚀行为．结果表明,随浸泡时间的延长,复合电极体系的阻抗不断增大;在浸泡初期,复合电极体系的阻抗谱中即出现了低频扩散阻抗,认为该阻抗由金属表面钝化膜的溶解产物的传质引起．扫描电镜（SEM）观察表明铬酸盐钝化膜呈现明显的裂纹形貌;利于溶解的铬盐通过裂纹到达合金基体使其钝化,是复合电极阻抗不断增大的原因所在．     

Direct synthesis of aligned cis-rich polyacetylene films using low-temperature nematic liquid crystals

Liquid crystal polymerization method has been extended so as to cover synthesis of cis-rich polyacetylene films with high alignment. Three kinds of liquid crystal mixtures which maintain nematic phase at lower temperature than 0 °C have been developed by using a series of liquid crystals of phenylcyclohexane derivatives because of their well-confirmed inertness towards Ti(OBu)₄ - AlEt₃ catalyst. It has been implied from DSC measurements that catalyst solutions using three, five and six component systems permit low-temperature polymerizations ranging from −20 to −30 °C, from −40 to −60 °C and from −10 to −45 °C, respectively. Polyacetylene films synthesized by using five and six component liquid crystals with and without an external magnetic force have high cis contents of 85 – 94 %. High alignment of fibril morphology of the films has also been confirmed through SEM observations. Measurements of electrical conductivity of the films upon iodine doping yielded a maximum conductivity of 1.6 × 10⁴ S/cm and electrical anisotropy of 7.0.     

Synthesis and properties of mono-substituted liquid crystalline polyacetylene derivatives—doping,magnetic orientation,and photo-isomerization

Mono-substituted acetylene monomers with a liquid crystalline (LC) group are polymerized using rhodium, iron or molybdenum complex catalysts. LC polyacetylene derivatives with number-averaged molecular weights of 4000–330000 were obtained in 5–92% yield. The LC behavior is examined by X-ray diffraction, differential scanning calorimetry, and polarizing optical microscopy. The polymers prepared using rhodium or iron catalyst are confirmed to assume a cis form and to undergo an irreversible isomerization to the trans form upon heating. Photo-responsive polyacetylene derivatives are successfully synthesized through the introduction of an azobenzene moiety as a mesogenic core into the side-chain, and these forms exhibit a reversible photochemical cis-to-trans isomerization of the azobenzene moiety.     

Photoexcitations in disubstituted polyacetylene: solitons and polarons

We studied the photoexcitations in films of disubstituted polyacetylene, a π-conjugated polymer with degenerate ground state. We found that the polymer in its pristine form supports charged and neutral topological soliton excitations. Photo-oxidized films or polymer/C₆₀ blends show, in addition, polaron excitations. At the same time the polymers show a strong emission band with high quantum efficiency, which leads to stimulated emission in thin films and lasing in cylindrical μ-cavities. These excitation properties are unique among polymers of both degenerate and non-degenerate ground state.     

Review of the synthesis of polyacetylene and its stabilization to ambient atmosphere

Two main topics in the field of polyacetylene are discussed. The first is the polymerization reaction, including the mechanism, the various catalytic systems with their selectivity and activity and the polymer morphology. The second is the polymer stability in ambient conditions, including the oxidation mechanism and the methods that are used or could be used for its stabilization.     

表面毛化不锈钢与纯铝的真空扩散连接

采用冷金属过渡技术(CMT)对不锈钢表面进行毛化,在其表面制备高度为3 mm、分布密度为9个/cm2的毛刺,毛刺中心横向及纵向间距均为3 mm. 研究其与纯铝进行真空扩散连接接头的界面组织和性能,分析不同保温时间对接头组织和性能的变化规律. 结果表明,在扩散连接温度为600 ℃,保温时间为60 min,压力为3 MPa的工艺条件下,表面毛刺刺入铝母材内部,使得表面氧化膜有效去除,接头形成连续的Fe₂Al₅+FeAl₃界面反应层,相比不锈钢与纯铝的直接真空扩散连接,接头拉剪强度显著提高. 此外,在扩散连接温度一定时,随保温时间的增加,反应层厚度增加,接头拉剪强度呈现先增大后减小的变化趋势.     

Toward a simple method for the fabrication of 1D or 3D nanostructures of polyaniline

We present a one-step chemical method for the fabrication and isolation of conjugated polymer nanostructures, in particular, polyanilines (PANIs), either in the pernigraniline or emeraldine oxidation state. The polymerization is initiated by the addition of a solid oxidant into an unstirred anilinium hydrochloride solution. This step allows a slow release of the oxidant, via its solubilization and diffusion into the undisturbed solution. The formation of visible macroscopic heterogeneous seeds promotes the homogeneous polymerization and growth of bulk nanostructures in solution. The shape of the first formed heterogeneous seeds was found to be dependent on the solubility/diffusion of the oxidant, allowing the prediction and control of the nanomorphology (1D vs. 3D or granular) of the bulk polyanilines. X-ray analyses of the as-prepared nanostructured PANIs showed that, compared to the literature data, the crystallite growth in the present study is significantly enhanced, with the 1D fibrillar morphology exhibiting a higher crystallinity per volume of nanostructure than that of a 3D granular counterpart. The electrical conductivity (σ ) of pelletized HCl doped PANIs or emeraldine salts (ES) showed significant differences depending on the fibrillar or granular morphology, but a close relationship among number of unit cells, crystallite size and electrical conductivity is evidenced.