在线紫外-可见光谱研究ITO导电玻璃电极上苯胺与对苯二胺的电化学共聚及其产物的表征

本文用在线紫外-可见光谱电化学的方法较详细地研究了在0.5M硫酸水溶液中苯胺、对苯二胺以及苯胺与对苯二胺混合体系在ITO导电玻璃电极上的电化学聚合和共聚合的过程。苯胺与对苯二胺在ITO导电玻璃上发生了电化学共聚合,在0.5M硫酸水溶液的纯苯胺和苯胺与对苯二胺共聚时的循环伏安曲线以及其对应的在线紫外-可见光谱表明对苯二胺的加入除了发生共聚外,也使聚合的速率明显加快;而且纯苯胺在循环伏安电化学聚合时在430nm处出现的吸收带因对苯二胺的加入而消失,说明对苯二胺的加入使聚合的机理与纯苯胺的聚合机理有明显不同,主要原因是苯胺产生的反应中间体可能很快与对苯二胺的阳离子自由基反应聚合。在导电玻璃ITO上的聚合物膜的反射傅立叶红外光谱表明,对苯二胺的加入可能产生了具有1,2取代模式结构,这说明了对苯二胺结合进入到聚合物中。这种共聚使得产物的表面形貌也发生了变化,聚合物扫描电镜图表明对笨二胺的加入有利于纤维状的表面形貌产生,纤维的直径可达到50nm粗细;同时用在线紫外-可见光谱研究了纯聚苯胺和共聚物随电位变化的电变色性质,结果表明在0v-0.6v之间共聚物与纯聚苯胺的在线紫外-可见光谱有明显的不同,且共聚物的电变色可逆性比纯聚苯胺好;同时SEM图也表明在0.8v电位下聚苯胺和共聚物表面形貌发生了团聚。     

电化学共聚邻甲基苯胺和邻氨基苯甲酸的在线紫外-可见光谱的研究

在0.5 mol/L H₂SO₄水溶液中, 以氧化铟锡(ITO)导电玻璃为工作电极, 用恒电位电解的方法, 在0.9 V电位下电化学共聚邻甲基苯胺(OT)和邻氨基苯甲酸(AA). 涉及的电化学聚合均用在线紫外-可见光谱进行跟踪, 结果表明电化学共聚随着反应体系中邻氨基苯甲酸的浓度的增加而变慢; 所得的均聚物和共聚物均用FTIR和扫描电镜表征. FTIR表明邻甲基苯胺和邻氨基苯甲酸之间发生了共聚; 扫描电镜图表明, 与聚邻甲基苯胺相比, 从200 mmol/L OT/50 mmol/L AA和150 mmol/L OT/50 mmol/L AA反应体系得到的共聚物具有小颗粒和较为致密的表面形貌; 这个现象也帮助证明了邻氨基苯甲酸应该与邻甲基苯胺发生了共聚, 并使表面形貌发生了改变.     

间甲基苯胺电化学聚合以及它与对苯二胺电化学共聚的 原位紫外-可见光谱

在0.5 mol•dm－3硫酸介质中, 循环伏安法电解间甲苯胺的原位紫外可见光谱图表明聚间甲基苯胺产生在氧化铟锡导电玻璃电极表面上. 在恒电位条件下, 用原位紫外-可见光谱较详细地研究了间甲基苯胺在氧化铟锡(ITO)上的电化学聚合. 结果表明间甲基苯胺只能在较高电解电位和单体浓度足够大的条件下才能发生电化学聚合. 在0.7 V(相对于饱和的Ag/AgCl), 0.2 mol•dm－3的间甲基苯胺和0.9 V, 20 mmol•dm－3的间甲基苯的实验条件下, 尽管在ITO电极上没有发生电化学均聚合, 但原位紫外-可见光谱表明在电极表面上可能还形成低分子量的齐聚物. 在低电位0.8 V下, 电化学聚合200 mmol•dm－3间甲苯胺时, 有明显的诱导期存在. 在恒电位电解的条件下, 相应的原位紫外-可见光谱和聚合物的傅立叶变换红外光谱(FTIR)表明间甲基苯胺和对苯二胺能发生电化学共聚反应, 由于对苯二胺可能与间甲基苯胺形成了具有较强反应活性的中间体, 使得对苯二胺的加入不但促进和加速了聚合反应, 而且还结合进聚合物中形成了phenazine或类似于phenazine的环结构.     

乙烯基二茂铁、丙烯酰胺和甲基丙烯酸二甲氨基乙酯共聚物的合成及性能研究

以乙烯基二茂铁、丙烯酰胺和甲基丙烯酸二甲氨基乙酯为共聚单体,采用自由基聚合法合成了具有水溶性和氧化还原活性的聚合物,并通过示差扫描量热法、傅里叶红外光谱、紫外-可见吸收光谱,及电化学方法对其玻璃化转变温度、化学组成、质子化作用及电化学性能进行了分析。实验结果表明该共聚物为乙烯基二茂铁、丙烯酰胺和甲基丙烯酸二甲氨基乙酯三元共聚物。该共聚物具有较好的水溶性和柔性,这些特点有利于提高修饰电极电子转移的效率,以及实现酶活性中心与电极之间的直接电子转移。共聚物中的甲基丙烯酸二甲氨基乙酯结构单元在近中性的溶液中可发生质子化作用,可与酶之间形成离子键从而有利于缩短酶活性中心与电极表面之间导电路径。共聚物的电化学性能表现出良好的氧化还原可逆性,且实现了共聚物与电极之间的可逆电子转移。另外该共聚物在溶液中的扩散系数较低,有利于提高修饰电极的稳定性。     

表面增强红外吸收光谱——表面敏感的原位免标记光谱电化学技术

表面增强红外吸收光谱（尤其衰减全反射表面增强红外吸收光谱）是一种超灵敏的红外光谱技术,能够实现亚单层膜水平的表面选择性探测. 由于增强基底可同时作为工作电极实现电化学调制,衰减全反射表面增强红外吸收光谱是一种表面敏感的原位免标记光谱电化学技术. 本文首先简要介绍了表面增强红外吸收光谱的基本原理和技术特点,之后通过代表性研究工作着重介绍近年衰减全反射表面增强红外吸收光谱电化学的应用和发展,最后展望了表面增强红外光谱所面临的挑战和潜在的研究方向.     

丹皮酚的电化学氧化及其反应机理研究

研究了在碱性磷酸盐缓冲溶液体系中,丹皮酚在固体电极上的电化学吸附氧化行为。与苯酚的电化学性质比较表明,碱性溶液中丹皮酚在电极表面上发生类似的不可逆的氧化。氧化产物发生随后化学反应,在电极表面生成致密的不导电聚合物膜。利用超微电极技术研究了丹皮酚电化学氧化的动力学过程,并用时间分辨快速扫描现场红外光谱电化学证明了电极表面的聚合物膜是芳醚类聚合物。     

离子液体［bmim］HSO4中合成的苯胺与环氧丙烷共聚物的电催化性能

 采用恒电流电解法,在1-丁基-3-甲基咪唑硫酸氢盐(［bmim］HSO4)离子液体中合成了苯胺与环氧丙烷共聚物(PAN-PPO). 扫描电镜观察表明, PAN-PPO由直径小于80 nm的纳米纤维组成. PAN-PPO对草酸氧化具有较好的电催化活性. 采用电化学原位红外光谱技术对草酸的电催化氧化进行了简单的分析.     

基于超微电极的原位电化学拉曼光谱

原位电化学拉曼光谱是一种重要的光谱电化学技术.基于超微电极的原位电化学拉曼光谱将拉曼光谱反映的结构信息与电极表面的电化学过程从实验上严格对应和关联,为深刻理解电化学反应机理提供依据.本文综述了采用超微电极作为工作电极的原位电化学拉曼光谱的研究方法和应用进展,总结了应用超微电极作为工作电极开展电化学拉曼光谱实验的方法和具有表面增强拉曼活性的超微电极制备方法,展示了如何利用在超微电极表面获得的拉曼光谱与界面电化学过程的严格关联研究单个锌颗粒电化学氧化过程、吡啶分子在Au电极表面的电化学吸附过程,以及如何利用该技术能以高的信噪比和灵敏度同时测量光电流与分子反应这一特性研究对巯基苯胺选择性光氧化反应.采用超微电极作为工作电极的原位电化学拉曼光谱技术极大拓展了拉曼光谱技术的研究范围,有望成为探索(光)电化学反应的有力工具.     

对硝基苯酚在酸性介质中的电化学还原反应机理

采用电化学原位红外光谱技术研究了对硝基苯酚在铜电极表面及硫酸介质中的电化学反应机理. 对硝基苯酚首先经电还原反应生成对亚硝基苯酚和对羟胺苯酚, 对亚硝基苯酚可发生缔合生成反式二聚体, 最后在较低的电位下, 对羟胺苯酚经电还原生成了对氨基苯酚.     

苯胺与邻甲氧基苯胺共聚的原位紫外-可见光谱电化学研究

运用循环伏安法(CV)和原位紫外-可见光谱电化学法研究了苯胺(AN)和邻甲氧基苯胺(OMA)单独聚合及二者共聚的电化学过程。在1.0 mol/L HCl溶液中,AN和OMA单独聚合及二者共聚时不同的电化学行为表明AN和OMA之间产生了共聚作用。原位紫外-可见光谱的研究表明,在AN与OMA的共聚过程中,AN和OMA首先分别被氧化生成其阳离子自由基,然后,AN和OMA的阳离子自由基与溶液中的AN和OMA单体发生交互反应产生混合二聚物中间体,在紫外-可见吸收光谱中对应于440 nm处的吸收峰。进一步研究发现,AN和OMA的共聚过程与溶液中各单体的浓度比有关,当混合溶液中OMA的浓度较大时,会对共聚产生抑制作用。采用红外光谱技术对共聚物进行了表征并初步探讨了共聚机制。结果表明,在AN和OMA共聚过程中,OMA分子掺杂进入AN聚合物骨架。     

Preparation and Electrocatalytic Activity of Polyaniline-poly（propylene oxide）

A novel copolymer of polyaniline-poly(propylene oxide) (PAN-PPO) was prepared by cyclic voltammetry (CV) and characterized by FFIR and SEM. It showed good electroactivity for methanol oxidation in H2SO4 solution.     

电活性超支化聚合物的合成与性质

通过分子设计, 利用A2+B3反应合成了一种新型电活性超支化聚合物材料. 该材料在保持聚苯胺的电活性基础上, 还具有超支化聚合物特有的低黏度(其特性黏度为0.33 dL/g)、低结晶性及良好的溶解性. 利用紫外-可见光谱对聚合物的氧化过程进行了监测. 热失重分析显示, 该材料具有较好的热稳定性, 失重10%时的温度高达517 ℃. 该材料具有较高的介电常数, 有望成为一种具有实际应用价值的高介电材料.     

DFT predictions of vibrational spectra of titanium tetramethoxide oligomers and the structure of titanium tetraalkoxides in liquid and solid phases

ATR FTIR spectroscopy and quantum chemical calculations were used to investigate temperature dependent changes of structure and polymer–water interactions in a comparative study of poly(ethylene oxide), poly(propylene oxide) and a series of ethylene oxide–propylene oxide–ethylene oxide tri-block copolymers (Poloxamers, Pluronics) with different lengths of the blocks in aqueous media. The observed wavenumber shifts and intensity changes of the bands of different chemical groups of polymers and of water molecules served as a basis for the determination of structural changes and interactions of polymer chains with the surrounding water molecules. It was found that both hydrophilic (ether group–water) and hydrophobic (methyl group–water) interactions are significant for the temperature dependent phase behaviour. A model for the structural changes during the temperature transitions was specified.     

Electrical and Structural Properties of Poly (Methyl Methacrylate) Doped Potassium Iodide (KI) Solid Polymer Electrolyte

A high-conducting salt-doped polymer electrolyte layer has been created here for use in photocell technologies. The solution casting method is used to produce ion conducting film where poly (methyl methacrylate) (PMMA) is used as the host polymer and potassium iodide (KI) as the dopant. The conductivity and amorphic increases of the polymer electrolytes with the addition of salt concentrations helps in the enhancement of the charge transfer properties. Using electrochemical impedance spectroscopy (EIS), ionic conductivity is evaluated where maximum conductivity is 3.99 × 10⁻⁶ S cm^-1 at 20 wt% KI concentration. Polarized optical microscopy (POM) shows the reduction in crystallinity by salt doping, while Fourier transforms infrared spectroscopy (FTIR) shows the complexation as well as composite nature of the film. Ionic transference number (t_ion) measurement shows the predominantly ionic nature of this polymer electrolyte.     

Bi-hybrid coatings: polyaniline-montmorillonite filler in organic-inorganic polymer matrix

A bi-hybrid composite is represented by an organic-inorganic (O-I) filler dispersed in an O-I matrix. Polyaniline-montmorillonite, as a nanocomposite filler, was synthesised by two independent processes: (1) montmorillonite was surface-modified with a conducting polymer, polyaniline, during the in-situ oxidation of aniline or (2) montmorillonite was pre-treated with aniline, then the aniline was polymerised and the polyaniline subsequently produced penetrated the montmorillonite structure. The organic-inorganic polymer matrix was formed in two independent steps: (1) inorganic building units were formed in situ by the sol-gel process, (2) followed by organic polymeric matrix formation by polyaddition reactions of epoxy groups with amines. Polyaniline-montmorillonite filler was added to the reaction system between these two steps, i.e. when the inorganic structures of the O-I matrix have already been formed but prior to formation of the organic polymeric matrix. Two different O-I matrices were prepared from functionalised organosilicon precursors and oligomeric amines. 3-[(Glycidyloxy)propyl]trimethoxysilane reacted with α,ω-oligo(propylene oxide) diamine and diethoxy[3-(glycidyloxy)propyl]-methylsilane reacted with α,ω-oligo(propylene oxide) triamine. The resulting bi-hybrid coatings, the O-I filler dispersed in the O-I matrix, were characterised by atomic-force and optical microscopies, and also by tensile tests. The filler composition affected both the mechanical and surface properties of the coatings.     

氧化偶联聚合方法合成电活性聚芳醚酮

通过氧化偶联聚合方法成功地合成出电活性聚芳醚酮. 该反应条件温和, 操作简单, 室温下即可进行. 用红外光谱、核磁共振谱、高效凝胶渗透色谱、循环伏安、热失重、X射线衍射等技术对所合成的聚合物进行了表征, 并探讨了聚合物的性能.     

聚醚环酰胺固体推进剂用键合剂的合成及使用性能

以丙三醇、环氧乙烷、环氧丙烷、氯化亚砜、异氰脲酸等为原料,合成了聚醚环酰胺键合剂。将其应用到推进剂(GAP/HMX/Al/AP)配方中,对成型后的推进剂进行力学性能测试和断面电子显微镜分析。结果表明,此类键合剂可以改善与推进剂中氧化剂的界面粘结性能,有效地提高成型后的推进剂在不同温度下的最大延伸率,但对抗拉伸强度的提高作用不明显。     

Synthesis and electrochemical properties of nanocomposites containing poly(3,6-bis(phenylamino)-2,5-dichlorobenzoquinone and multiwalled carbon nanotubes

The method of synthesizing nanocomposites based on multiwalled carbon nanotubes and a new polymer poly(3,6-bis(phenylamino)-2,5-dichlorobenzoquinone) containing polyaniline chains with electroactive substituents in the N-position is developed, and the electrochemical properties of the composites are studied. The in situ oxidative polymerization of N-substituted aniline performed in the presence of multiwalled carbon nanotubes makes it possible to design an organized, effective structure of the conducting composite material with enhanced electrochemical capacity and stable capacity parameters during long cycling in protic (1 mol/L H₂SO₄) and aprotic (1 mol/L LiClO₄ in propylene carbonate) electrolytes.     

ELECTROCHEMICAL COPOLYMERIZATION OF ANILINE AND AZURE B*

The electrochemical copolymerization of aniline and N,N,N'-trimethylthionin (azure B) in aqueous solutions hasbeen carried out using the potential sweep method, The optimum conditions for the coelectrodeposition are that the pH valueand the temperature of the electrolytic solution are controlled at 5.57 and 30℃, respectively, and the scan potential range isset between - 0.25 and 1.10 V (versus SCE). The copolymerization rate of aniline and azure B is about 3 times larger thanthat of aniline in the absence of azure B. The copolymerization of aniline and azure B was verified from the results of visiblespectra during electrolysis, FTIR spectra and the atomic force microscopy (AFM) images of the polymers. The in situ visiblespectrum for the electrolysis of the solution containing aniline and azure B is different from that of the respective aniline andazure B. The FTIR spectrum of the copolymer is not a superposition of that of polyaniline and poly(azure B). The AFMimage of the copolymer is different from those of polyaniline and poly(azure B) and is not a mixture of individual polymers.The conductivity of thc copolymer synthesized at pH 5.57 is four orders of magnitude higher than that of polyanilinesynthesized under the same conditions, bat in the absence of azure B. The clectrochemical properties of the copolymer aremainly attributed to polyaniline, but the copolymer has a better electrochemical reversibility and a much faster charge transferthan those of polyaniline.