Polybenzimidazole-Ester-Imides

Thermostable heterocyclic polymers containing benzimidazole and imide rings, as well as flexible ester groups, have been synthesized by solution polycondensation of diaminobenzimidazoles with dianhydrides incorporating preformed ester linkages. The thermal stability and the electrical insulating properties of these products are discussed and compared with related heterocyclic polymers.     

结构可控的炭基材料在锂离子电池中的应用

为了满足人们对高性能锂离子电池的需求,对电极材料进行结构设计和表面改性非常重要。基于炭材料独特的优势,通过使用炭材料或是制备炭基复合物能够极大地提高锂离子电池的电化学性能。基于本实验室的研究基础,本文总结了炭基材料在锂离子电池应用领域所发挥的重要作用,综述了炭材料和炭基复合材料作为锂离子电极材料的研究进展,着重阐述了通过引入炭材料和控制材料结构来提高电池电化学性能。在炭负极材料方面,主要概述了新型炭负极材料(碳纳米管、石墨烯和无定形炭)的各种形貌结构对电 化学性能的影响及各自的优缺点。在含炭复合电极材料方面,详细介绍了正负极复合材料的制备方法、结构设计、形貌控制及复合物中炭对于提高正负极活性材料的导电性和结构稳定性所发挥的积极作用。最后,对于炭基材料在锂离子电池领域需要解决的问题进行了探讨,以期提高锂离子电池的应用性能。     

The development of conductive composite surfaces by a diffusion-limited in situ polymerization of pyrrole in sulfonated polystyrene ionomers

Electrically conductive composite surfaces were prepared by a diffusion-controlled in situ polymerization of pyrrole in the surface layer of sulfonated polystyrene ionomer films. Premolded films of the ionomer sulfonic acid derivatives were sequentially immersed in aqueous solutions of pyrrole and FeCl₃, and polymerization occurred only where both the monomer and the oxidant were present. The penetration of the polypyrrole (PPy) into the film was controlled by varying the immersion time in the monomer solution. The amount of PPy produced depended on the immersion time of the film in the monomer and the degree of sulfonation of the ionomer. Surface conductivities of 10⁻⁴-10⁻¹ S/cm were achieved with PPy concentrations from 2 to 22 wt % and composite layers as thin as 15 μm. Intermolecular interactions occurred between PPy and the ionomer by proton transfer. Incorporation of PPy also increased the tensile strength of the ionomer film, significantly increased its modulus above T_g, and inhibited melt flow. © 1997 John Wiley & Sons, Inc.     

导电自愈合材料的研究进展及应用

高分子导电材料既具有金属的导电性又具有有机材料般的柔顺可加工性,在军事、能源、生物化学传感器等方面应用广泛。然而,其在制造使用过程中一旦发生破坏,就会造成电气元件的性能故障,甚至造成整个系统的瘫痪和报废。自愈合是人们模仿生物体损伤愈合的概念,解决材料损伤,延长材料使用寿命的新方法。本文综述了自愈合导电材料研究领域的最新动态,讨论了自愈合的机理和材料的制备方法,最后介绍了导电自愈合材料在超级电容器和电传感等方面的应用前景。我们相信导电自愈合材料的理论和应用研究会进一步推动电子器件领域的快速发展。     

PMMA/定向碳纳米管复合材料导电与导热性能的研究

Methyl Methacrylate(MMA) has been filled in the apertures of aligned carbon nanotubes(ACNTs). Then PMMA/ACNTs composites have been synthesized by in-situ polymerization. The SEM results show that carbon nanotubes are well dispersed and directionally arranged in the composites. The electrical conductivities of the parallel direction (parallel with ACNTs) and perpendicular direction (perpendicular with ACNTs) of composites were respectively tested to be 15 S·cm^-1 and 4 S·cm^-1, so the composites were conductivity anisotropic. Compared with PMMA, the thermal stable temperature of composites in air was improved by 100 ℃,and the thermal conductivity of composites was 13.64 times of PMMA.     

形状记忆聚偏氟乙烯/丙烯酸酯/碳纳米管纳米复合材料的导电及导热性能

利用聚偏氟乙烯（PVDF）微小结晶的物理交联点作用,制备了形状记忆性能优异的聚偏氟乙烯/丙烯酸酯聚合物（PVDF/ACM）共混材料,为提高其导电及导热性能,于其中引入了碳纳米管（CNT）,系统研究了PVDF/ACM/CNT三元体系纳米复合材料的导热及导电性能。 结果表明,碳纳米管在PVDF/ACM体系中分散均匀;在基本保持其形状记忆性能的前提下,碳纳米管的加入使材料导热性能及导电性能有较大程度的提高：质量分数为4%的CNT使材料25 ℃的电阻值降低至5000 Ω/square,导热系数提高至0.157 W/(m·K)。     

Synthesis, characterization and electrical conductivity of poly [ethyl trifluorobuty-2-noate]

Poly[ethyl trifluorobuty-2-noate] (PETFB) was prepared from ethyltrifluorobuty-2-noate by anionic polymerization.The polymer was examined by UV-Vis,IR and NMR spec-trometries.It possessed π-conjugated backbone in the main chain.No significant variation in the electrical conductivity of BF3-doped PETFB was observed after more than three months' storage,indicating improved conductive stability in air as compared with polyacetylene.     

分子导体(PyH)[Ni(dmit)2]2的合成、结构与导电性

合成了一种新的导电分子晶体(PyH)[Ni(dmit)_2]_2 (Py = pyridine, dmit = (C_3S_5)~(2-) = 4,5-dimercapto-1,3-dithiole-2-thione),用元素分析、红 外光谱对其进行了表征,并用四圆X射线衍射方法确定了结构,该晶体属于三斜晶 系,P-1空间群;晶胞参数为: a = 0.59227(4) nm,b = 0.82279(6) nm, c = 1. 67535(9) nm, α = 90.233(5)°, β = 92.107(5)°, γ = 104.654(6)°; V = 0.78925(9) nm~3, Z = 1. (PyH)[Ni(dmit)_2]_2晶体中,导电组元[Ni(dmit)_2] ~(-0.5) 沿b轴方向形成具有二聚体结构的柱状堆积,在(001)面形成以肩并肩分子 间的S…S强相互作用为特征的二维导电层,这种二维导电层上的室温电导率为0. 13 Ω~(-1)·cm~(-1),在c轴方向,(PyH)~+与[Ni(dmit)_2]~(-0.5)之间除库仑作 用外,还存在N-H…S,C-H…S氢键相互作用。单晶(001)面上变温电阻的测定结果 表明,在90 K到室温的温度范围内,(PyH)[Ni(dmit)_2]_2具有半导体导电行为, 导电激活能为0.15 eV。     

Synthesis and Characterization of Conducting Polyaniline Doped with Polymeric Acids

Conducting polyaniline doped with polymeric acids was synthesized by a in situ chemical polymerization method. The synthesized polymers were characterized by using UV‐Visible, FT‐IR spectroscopy and SEM analysis. Thermal stability of these polymers was evaluated by using TGA/DSC analysis. Among the three polymeric acids used for doping purpose, poly(vinyl sulphonic acid) doped polyaniline is found to be more conducting than those doped with other acids. From the temperature dependent conductivity measurements, an increase in conductivity with increase in temperature was observed.     

Electrical Percolation During Gelation of Lithium Doped Siloxane-Poly(oxyethylene) Hybrids

Gelation mechanisms of lithium-doped Siloxane-Poly(oxyethylene) (PEO) hybrids containing polymer of two different molecular weight (500 and 1900 g/mol) were investigated through the evolution of the electrical properties during the solgel transition. The results of electrical measurements, performed by in-situ complex impedance spectroscopy, were correlated with the coordination and the dynamical properties of the lithium ions during the process as shown by ⁷Li NMR measurements. For both hybrids sols, a decrease of the conductivity is observed at the initial gelation stage, due to the existence of an inverted percolation process consisting of the progressive separation of solvent molecules containing conducting species in isolated islands during the solid network formation. An increase of conductivity occurs at more advanced stages of gelation and aging, attributed to the increasing connectivity between PEO chains promoted by the formation of crosslinks of siloxane particles at their extremities, favoring hopping motions of lithium ions along the chains.     

Heavily Doped and Highly Conductive Hierarchical Nanoporous Graphene for Electrochemical Hydrogen Production

Heavy chemical doping and high electrical conductivity are two key factors for metal‐free graphene electrocatalysts to realize superior catalytic performance toward hydrogen evolution. However, heavy chemical doping usually leads to the reduction of electrical conductivity because the catalytically active dopants give rise to additional electron scattering and hence increased electrical resistance. A hierarchical nanoporous graphene, which is comprised of heavily chemical doped domains and a highly conductive pure graphene substrate, is reported. The hierarchical nanoporous graphene can host a remarkably high concentration of N and S dopants up to 9.0 at % without sacrificing the excellent electrical conductivity of graphene. The combination of heavy chemical doping and high conductivity results in high catalytic activity toward electrochemical hydrogen production. This study has an important implication in developing multi‐functional electrocatalysts by 3D nanoarchitecture design.     

Effects of Oil on Aqueous Foams: Electrical Conductivity of Foamed Emulsions

Three‐phase foams containing dispersed oils (also called foamed emulsion) are usually encountered in such areas as enhanced oil recovery, food foams, and in foams containing antifoams. The presence of oil causes these complex fluids to exhibit extraordinary properties in contrast to aqueous foams. We experimentally investigated, for the first time, the conductive properties of the foamed emulsions and found that the electrical conductivity increases monotonically with the volumetric liquid fraction, presenting a linear relationship. Combined with the analysis on the foaming capacity and microstructure of this complex fluid, the conductive mechanism is revealed. In these foamed emulsions, the whole conductive network is comprised of two levels of structural hierarchy, which displays a different mechanism from those of the conventional aqueous foams. The lamella of emulsions is taken as primary electrical channel, whereas the secondary electrical channel occurs in the lamella between two bubbles. This conductive behaviour is attributed to the microstructure properties of the foamed emulsions. We believe that such findings are potentially important for a better understanding of the fundamentals of these tri‐phase dispersion systems.     

Computer models for electrical conductivity of multicomponent solid-state systems

Models for the computer simulation of electrical conductivity of polycrystalline materials and mixtures are proposed. The effect of model parameters on the concentration behavior of conductivity is considered. The correspondence between the model parameters and the characteristics of physical objects is established, thus making it possible to analyze the spatial relations in solid-state systems.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 1868–1873, November, 1993.     

Novel preparation of electrically conducting poly (vinyl chloride) by photo-dehydrochlorination from poly (vinyl chloride)/polypyrrole composite film

Polypyrrole (PPy) was deposited electrochemically on a platinum plate from a nitric acid solution of pyrrole. The PVC/PPy composite film was finally obtained by casting poly(vinyl chloride) (PVC) onto the PPy electrode from a tetrahydrofuran solution of PVC. The prepared composite film was irradiated at 90°C with a low-pressure mercury lamp in the stream of hydrogen gas saturated with steam, and the PVC film was dehydrochlorinated, leading to the formation of conjugated polyene. The electrical conductivity (σ) of the PVC film in the irradiated composite film was reveled: σ=2.51 × 10^?5S cm^?1. By iodine doping, σ was further enhanced up to 5.04 X 10^?3 S cm^?1. The tensile strength of the irradiated composite film became larger than that of the original PVC film; i.e., the stress at break was: 461 (composite film); 401 kg cm^?2 (PVC). These results were brought about by the doping of radical species to the conjugated polyene. The anion, NO^?₃, doped during the electrodeposition of PPy was photodecomposed to generate radical NO₂ and this species was doped to the polyene, resulting in the formation of electrically conductive PVC and mechanically improved composite film. © 1994 John Wiley & Sons, Inc.