Neutral Pd(II) and Ni(II) Acetylide Catalysts for the Polymerization of Methyl Methacrylate

Homogenous polymerization of methyl methacrylate using Pd(II)- and Ni(II)-based acetylide complexes as initiators has been investigated. M(PR'₃)₂(CCR)₂ (M=Pd, Ni; R'=PPh₃, Pn-Bu₃; R=Ph, CH₂OH, CH₂OOCCH₃, CH₂OOCPh, CH₂OOCPhOH-o) were found to be a novel type of effective initiators for the polymerization of methyl methacrylate. Among them, Pd(C CPh)₂(PPh₃)₂ (PPP) shows the highest activity in the MMA polymerization and the PMMA obtained is a syndiotactic polymer with high number-average molecular weight (M _n) of 14.1 × 10⁴. Some features and kinetic behavior of MMA polymerization initiated by PPP were studied in detail. The polymerization reaction is first-order with respect to both [PPP] and [MMA]. Radical polymerization mechanism is proposed.     

苯乙烯-马来酸酐交替共聚物钠盐/聚苯乙烯磺酸钠复合物的湿敏特性

以苯乙烯-马来酸酐交替共聚物钠盐(NaSMA)与聚苯乙烯磺酸钠(NaPSS)复合物为湿敏材料,在叉指金电极上浸涂成膜制备了电阻型湿度传感器,考察了NaSMA和NaPSS浓度对复合湿度传感器响应特性的影响.研究表明,加入NaPSS可降低传感器在低湿下电阻,同时提高传感器的高湿灵敏度.在最佳条件下,当环境湿度从33%RH增...     

汕头市区软土的工程地质特性

通过对汕头市区软土的物理力学性质和工程地质特性的研究表明,饱和状态软粘土的物理力学性质均与含水量的关系密切。软土的压缩性质与抗剪强度,随土的结构强度的改变而出现异常,为此,在软土地区开展工程勘察,应配合适当数量的原位十字板剪切试验和静力触探试验等原位测试手段,以更精确地了解软土的工程地质特性。     

构网型直驱风电机组间控制相互作用研究

构网型风电控制技术具有很好的弱电网适应性,可以有效避免风电并网次超同步振荡问题。但是虚拟同步控制引入固有的低频特征模式,接入强电网时会发生低频振荡,同时多台构网型风电机组并联运行时存在控制器相互作用。针对此问题,采用特征模式分析方法,研究了基于虚拟同步控制方法的构网型直驱风电机组并联运行时的控制相互作用及主导低频特征模式稳定性。揭示了虚拟惯量控制参数及系统运行方式对构网型风电机组并联运行低频振荡特性的影响。通过详细时域仿真验证了分析结果的正确性。     

Water-soluble polyaniline and its composite with poly(vinyl alcohol) for humidity sensing

Water-soluble polyaniline (PANi) was prepared by a “green” method with poly (stryrenesulfonic acid) (PSSA) as a template, and characterized by UV–vis spectroscopy, FT-IR spectroscopy, transmission electron microscopy (TEM) and atomic force microscopy (AFM). It was found that the films of PANi and its composite with poly(vinyl alcohol) (PVA) were composed of nanoparticles. The humidity sensitive properties of the both PANi and its composite with PVA were investigated at room temperature. The water-soluble PANi exhibited high sensitivity (impedance change over three orders of magnitude in the range of 15–97%RH) and good sensing linearity on a semi-logarithmic scale, but a relatively large hysteresis of ～8%RH. In contrast, the composite of PANi and PVA showed a very small hysteresis of ～2%RH. Moreover, the response was fast and highly reversible. The humidity sensing mechanism of the composite of PANi with PVA was explored by measuring its complex impedance spectra under different humidities.     

Chloro-Nickel and Chloro-Cobalt Complexes Containing Phosphine Ligands: Efficient Initiators for Polymerization of Alkynes

We have developed a new series of single-component air- and moisture-stable catalysts for alkyne polymerization based on chloro-nickel and chloro-cobalt complexes containing phosphine ligands. The polymerization of p-diethynylbenzene initiated by these complexes proceeds smoothly in the presence of amines at room temperature to afford soluble -conjugated polymers in yields as high as 81% with weight-average molecular weight up to 17 600.     

Synthesis,characterization and comparative photovoltaic behavior of diketopyrrolopyrrole (DPP)-containing poly(phenylene vinylene)s varying at N-alkyl or 3,6-aryl substituents in DPP units

Three new diketopyrrolopyrrole (DPP)-containing poly(phenylene vinylene)s varying at N-alkyl or 3,6-aryl substituents in DPP units, abbreviated as C6DPPDHPV, C6DTDPPDHPV, and C62DTDPPDHPV, were designed to comparatively study the structural effects on their photophysical, electrochemical properties, molecular organization and photovoltaic properties. The polymers exhibited remarkably broad UV–vis absorption spectra covering a major part of the wavelength range of visible light in the solar spectrum, and small bandgaps between 1.4 and 1.9 eV. X-ray diffraction and cyclic voltammetry measurements revealed that N-alkyl and 3,6-aryl in DPP unit played a key role in tuning their molecular organization as well as electrochemical behavior. The bulk heterojunction photovoltaic devices employing the three polymers as electron donors, together with PC₆₁BM as electron acceptor, were examined. C6DPPDHPV based device showed the highest energy conversion efficiency of 0.72%. Lower hole mobilities and relatively higher HOMO energy levels may be responsible for inferior performance of C6DTDPPDHPV and C62DTDPPDHPV-based devices. Moreover, the C6DPPDHPV was preliminarily evaluated as active material in organic thin film transistor.     

Novel amphiphilic polymer gel electrolytes based on (PEG‐b‐GMA)‐co‐MMA

Amphiphilic conetwork–structured copolymers containing different lengths of ethylene oxide (EO) chains as ionophilic units and methyl methacrylate (MMA) chains as ionophobic units were prepared by free radical copolymerization and characterized by FTIR and thermal analysis. Polymer gel electrolytes based on the copolymers complexed with liquid lithium electrolytes (dimethyl carbonate (DMC) : diethyl carbonate (DEC) : ethylene carbonate (EC) = 1 : 1 : 1 (W/W/W), LiPF₆ 1.0M) were characterized by differential scanning calorimetry and impedance spectroscopy. A maximum ion conductivity of 4.27 × 10^?4 S/cm at 25^oC was found for the polymer electrolyte based on (PEG2000‐b‐GMA)‐co‐MMA with long EO groups. Moreover, the effect of temperature on conductivity of the amphiphilic polymer electrolytes obeys the Arrhenius equation. The good room temperature conductivity of the polymer electrolytes is proposed to relate to the enhancement in the amorphous domain of the copolymers due to their amphiphilic conetwork structure. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

具有双层结构的聚电解质和聚苯胺复合湿度传感器

制备了水溶性聚苯胺,将其与聚电解质湿敏材料———交联季胺化聚（4-乙烯基吡啶）复合,构建了具有双层结构的电阻型湿度传感器,研究了其在低湿环境下的湿敏响应特性。