【作者】 庞月红；

【导师】 金利通；

【作者基本信息】 华东师范大学 ， 分析化学， 2008， 博士

【摘要】 导电聚合物是近年来电化学研究的热点之一。聚噻吩及其衍生物因具有高度的稳定性,优良的导电性,较高的电化学活性,较好的电致变色性能以及多方面的应用前景而在导电聚合物研究领域中占有重要的地位。聚合物一般采用化学方法和电化学方法合成。与化学方法相比,电化学聚合法具有掺杂过程可以定量控制,所得产物可进行可逆的氧化还原反应,以及制备聚合物膜质地均匀等优点。离子液体与传统溶剂相比,有其独特的性能。例如蒸气压低、不易挥发、可循环利用以及环境友好、电导率高、酸碱性可调、具有很大的电位窗（4V）等。同时离子液体又是理想的电化学介质材料,能溶解很多有机物、无机物,具有良好的化学稳定性和热稳定性,所以离子液体可望用做电化学聚合的介质。Rogers等在2003年Science上预言在未来的十年间离子液体将在许多应用领域中取代传统的有机溶剂,甚至应用在传统溶剂不能应用的领域中。然而导电聚合物电化学聚合及电致变色方面的研究一般是在有机溶剂中进行的,在离子液体中的报道尚少,因此在离子液体中采用电化学方法合成导电聚合物具有较好的理论意义及应用价值。电致变色材料是目前最有应用前景的智能材料之一。用这类材料制成的灵巧窗、反射镜、显示器等电致变色器件给人们的生活带来了极大便利。因此,寻找性能优良的电致变色材料、研发电致变色器件已日益成为科研工作的热点。导电聚合物作为一类重要的电致变色材料具有其独特的优点,如成本低、韧性佳、加工性能好,光学质量好,颜色转换快,循环可逆性好,且能通过修饰分子结构改善变色性能。共聚是一种提高电学和力学性质的有效手段,同时也可以对聚合物的电致变色的性质加以调控。随着纳米技术的发展,纳米复合电致变色膜作为一类新型的电致变色材料受到人们的日益重视。本论文使用离子液体作为溶剂和支持电解质,通过电化学方法制备噻吩衍生物的均聚、共聚及纳米复合电致变色膜。通过红外光谱、扫描电子显微镜和热重和差热分析法等对膜的性质进行表征,并利用循环伏安法、紫外可见光谱法、循环电位扫描吸收法、计时安培法、计时电势法和计时吸收响应曲线法对膜的电化学和电致变色的特性进行表征,并在此基础上构筑电致变色器件。本论文内容共分六章:第一章绪论本章内容主要包括离子液体、导电聚合物、电致变色材料、电致变色器件四部分。文中简要介绍了离子液体的种类、特性、制备,着重综述了离子液体在电化学中的应用;介绍了导电聚合物的制备、性能表征方法和它的应用前景。对电致变色的种类及性能进行了概述。介绍了电致变色器件的制备、结构及工作原理并详细地阐述了它的应用及前景。第二章离子液体中聚（3-溴噻吩）的电化学合成和电色效应研究本章以1-丁基-3-甲基咪唑六氟磷酸盐离子液体[BMIM]PF₆既作为溶剂又作为支持电介质,通过恒电流、循环伏安等方法制备聚（3-溴噻吩）（PBrT）膜。采用红外光谱（FT-IR）和扫描电子显微镜（SEM）对PBrT膜的结构和形貌进行表征,用热重和差热分析法（TG-DTA）研究聚合膜的热稳定性,并利用紫外可见光谱（UV-Vis）、计时电流和计时吸收曲线研究该聚合膜电化学和电致变色的特性。研究结果表明,与传统方法比较,在离子液体[BMIM]PF₆中制备的PBrT膜更致密、光滑,具有良好的可逆性和充放电能力,电活性高,热稳定性好。以该方法制备的PBrT膜颜色变化明显,响应时间快。由于离子液体具有电位窗宽、导电率高、可循环利用等优点,因此在电化学聚合等方面具有良好的应用前景。第三章离子液体中3-氯噻吩聚合物的电化学合成及其电色效应的研究本章以1-丁基-3-甲基咪唑六氟磷酸盐离子液体[BMIM]PF₆作为溶剂和支持电解质,用循环伏安法和恒电流法制备3-氯噻吩均聚物（PCIT）及3-氯噻吩和3-甲基噻吩的共聚物P（ClT-co-MeT）。运用傅立叶变换红外光谱法对聚合物膜的分子结构进行证实,并利用循环伏安法、紫外可见光谱法、循环电位扫描吸收法、计时安培法、计时电势法和计时吸收响应曲线法对聚合物膜电化学和电致变色的特性进行表征。研究结果表明,共聚物比3-氯噻吩均聚物具有更可逆的氧化还原性质,更快的响应时间（0.9s）,更高的对比度（26%）和更长的循环寿命（2300次）。第四章离子液体中电化学合成高质量的电致变色聚3-烷基噻吩衍生物本章以室温离子液体1-丁基-3-甲基咪唑六氟磷酸盐[BMIM]PF₆为溶剂及支持电解质通过恒电流和循环伏安等方法制备聚3-甲基噻吩（PMeT）、聚3-己基噻吩（PHexT）和聚3-辛基噻吩（POcT）。并在[BMIM]PF₆:CH₃CN（1:1,v/v）溶液中通过紫外可见光谱、计时电流、计时库仑以及计时吸收曲线等方法对聚合物膜的光谱电化学和电致变色特性进行表征。PMeT、PHexT和POcT膜在还原状态下为亮红色、桔红色和桔黄色,并能经过电化学掺杂可逆地转变为亮蓝色、蓝色和黑蓝色。实验结果表明,三种聚合物膜具有高的颜色对比度（46%,45%和39%）,较短的响应时间（1.1 s,1.4 s和1.9 s）和高的电致变色着色效率(250,220,230 cm²C^-1)以及长的循环寿命。第五章PCIT/TiO₂纳米复合膜的制备及其电致变色性质和器件的研究以室温离子液体1-丁基-3-甲基咪唑六氟磷酸盐[BMIM]PF₆为溶剂和支持电解质,在纳米多孔TiO₂表面通过恒电流法制备聚（3-氯噻吩）（PClT）。通过光谱电化学以及动力学对该PClT/TiO₂纳米复合膜的电致变色特性进行表征,并在此基础上制备该复合膜的电致变色器件。研究结果表明,该纳米复合膜具有高的电致变色对比度、合理的响应时间、长的循环寿命以及良好的与基底粘附能力,且该复合膜制成的固态电致变色器件（ECD）具有很好的电致变色性能和长的循环寿命,有望成为一种新型的具有应用前景的电致变色器件。第六章Ag/WO₃纳米复合膜制备及与聚3-烷基噻吩构筑电致变色器件的研究通过真空镀膜方法制备的纳米Ag薄膜均匀致密,表面光滑。然后通过电化学方法在Ag纳米薄膜上沉积一层三氧化钨（WO₃）,制备纳米Ag/WO₃复合膜。并在此基础上构筑五层式玻璃/ITO/纳米Ag-WO₃复合膜/固态电解质/聚（3-甲基噻吩）/ITO/玻璃电致变色器件。实验结果表明,与传统的WO3膜相比,纳米Ag/WO₃复合膜具有更好的电化学活性、更高的对比度、更短的响应时间,以及更好的稳定性。由该复合膜组装的电致变色器件工艺简单,电致变色性能良好。更多还原

【Abstract】 Conjugated polymers stand for a family of important electrochromic materials. Among these conjugated polymers,Polythiophene and its derivatives are the most challenging class and gain popularity due to their unique advantages,such as low cost, good processibility,rapid response time,high optical contrast,flexibility for large-area application,and the ability to modify their structure to create multicolor electrochrome.They can be prepared by chemical or electrochemical methods. Among these methods,electrochemical techniques are particularly appropriate for controlled synthesis of these compounds and for the isolation of a well-defined oxidation state.The preparation,characterization and application of electrochemically active,electronically conjugated polymeric systems are still in the foreground of research activity in electrochemistry.Room temperature ionic liquids（RTIL）have been put in a wide range of synthetic application as green solvents during the past decade for their good chemical and physical properties.The use of ionic liquids is often initiated by their recyclable use and more environmentally benign,where the negligible volatility and non-flammability of ionic liquids make them ideal replacements for more toxic molecular solvents,importantly,overcome the problem of solvent evaporation that exists with the long-term use of volatile solvents in electrochemical applications. Rogers et al.predicted in 2003 Science that the next decade should see ionic liquids being used in many applications where conventional organic solvents are used today. Furthermore,ionic liquids will enable new applications that are not possible with conventional solvents.Especially air and moisture stable ionic liquids,with high electrical conductivities,excellent thermal and chemical stability,stable over a wide temperature range,good solvent transport properties,negligible vapor pressures and wide electrochemical windows（typically over 4V wide）and good solvents for a wide range of organic and inorganic materials,were expected to be a promising medium for electrochemical synthesis and application.In recent years,there has been great interest towards electrochromic applications and device fabrication,such as display panels,electrochromic mirrors and smart windows.Conducting polymers stand for a family of important electrochromic materials that have gained popularity due to their unique advantages,such as low cost, good processibility,flexibility for large-area application,and the ability to modify their structure to create multicolor electrochrome.Copolymerization by introducing new groups alters the existing structure and band gap,leading to absorption at different wavelengths and colors,which offers a means of controlling the electrochromic properties of conducting polymers.With the development of nanotechnology,conducting polymer/metal oxides nanocomposite films as a family of electrochromic materials has also gained extensive attention.In this thesis,electrochemical synthesis of homopolymer,copolymer and nanocomposite were carried out via potentiodynamic and galvanostat methods by using ionic liquid as the growth medium and the supporting electrolyte.The properties of these films were characterized by the means of the FT-IR spectrum,the scanning electron microscopy（SEM）thermogravimetry and differential thermal analysis （TG-DTA）.The electrochemical and electrochromic properties were examined with cyclic voltammetry（CV）,UV-Vis spectrum,chronoamperometry,and chronoabsorptometry.Based on this,electrochromic device was constructed and its electrochromic properties were also investigated.Totally,there are six chapters in this paper.The first chapterThis chapter has four parts,that is,ionic liquid,conduct polymer,electrochromic material and electrochromic device.The sort,speciality and preparation method of ionic liquid has been brief introduced,and its application in electrochemistry has also been reviewed in detail.Then conduct polymer’s preparation method,various characterized technique and its application prospect has been discussed.The speciality and properties of electrochromic materials has also been reviewed.Lastly,we introduce the preparation,structure and mechanism of electrochromic device and review its application and prospect.The second chapterIn this chapter,stable ionic liquid likel-butyl-3-metyllimidazolium hexafluorophosphate[BMIM]PF₆ has been used as solvent and electrolyte for the electropolymerization of 3-bromothiophene by galvanostat and cyclic voltammetry. The structure and morphology of PBrT films were characterized by the means of the FT-IR spectrum and the scanning electron microscopy（SEM）.The thermal stability of PBrT have been investigated through thermogravimetry and differential thermal analysis（TG-DTA）.The electrochemical and electrochromic properties of PBrT flims were examined with UV-Vis spectrum,chronoamperometry,and chronoabsorptometry. The results showed the surface morphology of PBrT films that prepared in ionic liquid were denser and much smaller than that prepared in traditional solvent,and the PBrT films had good stability,reversibility,high electrochemical capacity and super thermal stability.Electrochromic performance of the PBrT films that prepared in ionic liquid showed a good color contrast and comparative response time.Simultaneously,ionic liquids exhibit wide electrochemical potential window,high ionic conductivity and recyclability.Therefore,they are promising to electropolymerization and so on.The third chapterIn this chapter,electrochemical homopolymerization of 3-chlorothiophene（ClT） and copolymerization with 3-methylthiophene（MeT）were carried out via potentiodynamic and galvanostat methods by using ionic liquid （1-butyl-3-methylimidazolium hexafluorophosphate,[BMIM]PF₆）as the growth medium and the supporting electrolyte.Both homopolymer（PClT）and copolymer P（ClT-co-MeT）were characterized via cyclic voltammetry（CV）,Fourier transform infrared spectroscopy（FTIR）,spectroelectrochemical analysis and kinetic study. Homopolymer revealed color changes between deep red and deep blue,whereas copolymer showed the most vivid change of color between bright red and greenish blue in fully reduced and oxidized states.Via kinetic studies,switching time and the maximum optical contrast%△T were found to be 2.4 s and 17%for PClT,0.9 s and 26%for P（ClT-co-MeT）.Compared with PClT（580 times）,the copolymer exhibited a long-term switching stability up to 2300 double switches.Results implied that copolymerization is a valuable approach to achieve the desired electrochromic properties. The fourth chapterIn this chapter,electrochemical polymerization in a room temperature ionic liquid,1-butyl-3-methylimidazolium hexafluorophosphate（[BMIM]PF₆）,has been used to prepare electrochromic poly（3-methylthiophene）（PMeT）and its more attractive derivatives:poly（3-hexylthiophene）（PHexT）and poly（3-octylthiophene） （POcT）.Spectroelectrochemistry and electrochromic properties of the resulting polymers were characterized using various experiment techniques in [BMIM]PF6/CH3CN（1:1,v/v）solution.The thin films were bright red,orange red and orange yellow at its fully reduced state for PMeT,PHexT and POcT,respectively. After oxidization of these undoped polymers,the films underwent reversible change to the bright blue,blue or black blue form.These poly（3-alkylthiophene）s（PMeT, PHexT and POcT）films exhibit high chromatic contrast（46%,45%or 39%）, comparative switching times（1.1,1.4 or 1.9 s）,great electrochromic efficiency(250, 220,230 cm²C^-1)and long-term switching stability.High quality electrochromic polymers were provided for the use of commercially available thiophene monomers, avoiding the use of other custom synthesized monomers.The fifth chapterIn this chapter,poly（3-chlorothiophene）（PClT）was electrochemically synthesized on a nanoporous TiO₂ surface in the ionic liquid 1-butyl-3-metyllimidazolium hexafluorophosphate by galvanostat method to control charge density of 93 mC cm^-2.Spectroelectrochemical analysis presented that the PClT/TiO₂ nanocomposite film had an electronic bandgap of 1.80 eV with a bordeaux color in the reduced form and a dark blue color in the oxidized form.The switching ability of the PClT/TiO₂ nanocomposite film was monitored and the percent transmittance was measured as 12%at 555 nm and 25%at 770 nm.Moreover,a PClT/TiO₂ nanoeomposite film based electrochromic device was constructed and its electrochromic properties were also investigated in this paper.The sixth chapterAg nanoparticle film,which was fabricated by vacuum deposition method from high purity Ag wire onto cleaned ITO,was uniform and smooth.Ag/WO₃ composite film was prepared by cathodic electrodeposition of WO₃ onto the surface of Ag nanoparticle film.Moreover,Ag/WO₃ nanocomposite film based 5-layer electrochromic device（glass/ITO/Ag-WO₃ nanocomposite film/solid electrolyte/poly（3-methythiophene）/ITO/glass）was constructed and its electrochromic properties were also investigated in this paper.In comparison with a single component system（WO₃）,a substantial enhancement in the electrochromic performance for the Ag embedded WO₃ composite system was clearly observed.The method of constructing this electrochromic device was simple and electrochromic properties appeared good.更多还原