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Polyaniline, polyaniline / nanoparticles composites and Spectral & Electrochemical studies

By 焦连升


导电聚合物在防腐、传感和二次电池等方面具有很高的应用价值。表面增强拉曼光谱(SERS)对界面信息有较高的灵敏度和选择性,特别是原位技术可以提供详细的界面信息。我们确定了用本实验室己经很成熟的自组装膜技术对电极进行功能化修饰,再结合原位电化学SERS方法对聚苯胺的电化学初聚过程进行研究,进一步了解了聚合成膜的机理;为有目的地构造具有特殊结构和用途的聚苯胺以及聚苯胺与纳米粒子的复合功能材料提供理论依据。1.在4-ATP/金修饰电极上化学接枝制备4一琉基偶氮氨基苯单层膜;我们首先在经电化学氧化还原粗糙化处理的金电极上组装了4-ATP分子并且得到了具有较高信噪比的拉曼增强信号;继而我们又利用经典的重氮化偶联反应接枝了苯胺分子得到了稳定的具有较高电化学活性的对琉基偶氮苯单层膜。2.在4-ATP/金修饰电极上进行了苯胺电化学聚合过程的原位SERS研究;通过采用原位电化学循环伏安一表面增强拉曼光谱法,研究了在硫酸介质下苯胺在4-ATP修饰的金电极上的起始聚合情况,并与未经修饰的裸金电极进行了对比,认为:具有高度电子导电性的4-ATP分子对苯胺的聚和起到了促进作用;得到的聚苯胺薄膜继承了4-ATP分子自组装膜的有序结构,采取的是苯胺的C_4位与下层的4-ATP分子的N位进行头一尾偶联聚和。3.聚苯胺与金属和非金属纳米复合材料的制备;全部采用电化学聚合的方法,制备了聚苯胺/金纳米粒子,聚苯胺/碳纳米管,聚苯胺/碳纳米管/金纳米粒子/的复合膜。通过形貌和电化学表征,认为金纳米粒子和碳纳米管在聚苯胺膜中分布均匀,形成了比较好的复合材料,且具有良好的导电性能,有望在二次电池和传感器方面有较好的应用。Conducting polymers are of particular interest for the material researches because of their promising applications in corrosion, sensors, secondary batteries, etc. Surface-enhanced Raman Scattering (SERS) spectroscopy, especially in-situ SERS measurements, can provide detailed information of the chemical bond vibrations on adsorbate/substrate surface due to its high sensitivity and selectivity. We explored the mechanism of electropolymerization of aniline on SAMs-modified Au substrate using in-situ SERS technique, which may provide more theoretical evidence towards preparation of functionalizing conducting polymer materials or composite materials of conducting polymers and metallic and nonmetallic nanoparticles, such as gold nanoparticles, carbon nanotubes, etc. 1. Simple Azo Derivatization on 4-Aminothiophenol/Au Monolayer; First, a SERS spectrum of 4-ATP monolayer on a roughened Au surface with a high S/N ratio was obtained. Then a stable and redox active monolayer of para-mercaptodiazoaminobenzene was achieved by direct diazotization on such a 4-aminothiophenol/Au monolayer. Electrochemical and surface-enhanced Raman scattering spectroscopy (SERS) measurements were conducted before and after the reaction to ensure the electroactive derivatization. 2. In-situ Electrochemical SERSS Studies on Electrodeposition of Aniline on 4-ATP/Au Surface; The electrochemical polymerization of aniline in 1 M H2SO4 aqueous solution of 0.01 M aniline monomer on roughened Au surface modified with a self-assembled monolayer (SAM) of 4-aminothiophenol (4-ATP) has been investigated by in situ electrochemically surface-enhanced Raman scattering spectroscopy (SERSS). The repeat units and possible structures of the electrodeposited polyaniline (PANI) film were proposed, i.e. aniline monomer is coupled in head-to-tail predominately at the C4 of aniline and amine of 4-ATP, and the thin PANI film is orientated vertically to substrate surface. Simultaneous Raman spectra during potential scanning indicate clearly that the ultrathin PANI film (in initial growth of the film) consists of semiquinone radical cation (IP+), para-disubstituted benzene (IP and IP4) and quinine diimine (NP) while it is oxidized, and without quinine diimine and semiquinone radical cation while reduced. Meanwhile, the results confirm that '-' 4-ATP monolayer shows a strong promotion on the electrodeposition of aniline monomer and a possible polymerization mechanism was proposed too. 3. Preparation and Characterization of Polyaniline/Au, Polyaniline/CNTs and Polyaniline/ CNTs /Au composites. Composites of polyaniline/Au, polyaniline/CNTs and polyaniline/CNTs/Au were successfully prepared, totally by the electrochemical methods. SEM results show that Au nanoparticles and multi-walled carbon nanotubes dispersed evenly in the polyaniline matrix. Moreover, the composites display excellent electron conductivity

Topics: 偶氮, 衍生化, 聚苯胺, 复合材料, 分析化学
Year: 2005
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