【作者】 张昊宇；

【导师】 王晓工；

【作者基本信息】 清华大学 ， 材料科学与工程， 2009， 博士

【摘要】 导电高分子具有很多独特的电学和光学性能,是一类十分重要的功能高分子材料。偶氮聚合物具有独特的光响应性和潜在的应用前景。制备同时包含这两种聚合物的分子复合材料和相关的纳/微米结构,系统研究其功能性是本论文研究的重点。本论文对有关分子复合材料的制备方法、纳/微米结构控制、电化学活性和光响应性能等进行了深入研究,取得了如下的创新性成果。通过静电逐层吸附方法,制备了聚苯胺分别和四种偶氮聚电解质(PPAPE、PNACN、PNANT和PNATZ)的自组装多层膜。通过改变溶液的浓度和pH等,薄膜的层厚和内部结构可以得到精确控制。这类自组装多层膜具有多种电活性和光响应性,特别是具有丰富的电致变色功能性。通过改变偶氮聚电解质的种类和层数,自组装多层膜可表现出不同的电致颜色变化。建立了一种结合电化学聚合和静电逐层自组装制备多层膜的新方法。该方法利用电化学沉积制备导电高分子层,利用静电吸附引入聚电解质层。通过对不同类型的导电高分子(PANI、PPY和PEDOT)和聚电解质(PNACN、PNANT、PEDOT:PSS)以及羧化MWNT等体系的研究,证明了该方法具有很好的普适性,具备成膜快、薄膜增长可控等优点。该方法是一种制备偶氮聚电解质和不溶性导电高分子复合多层膜的有效新途径。利用模板电化学聚合、模板静电逐层自组装和软刻技术等,成功制备了导电高分子(PEDOT)的有序多孔介孔薄膜、超支化大分子重氮盐/聚(3-乙酸噻吩)的中空微囊泡,聚苯胺的表面起伏光栅等。系统研究了聚苯胺光栅在不同酸掺杂和电化学氧化还原电位条件下的光栅衍射效率变化规律,利用Lorentz振子模型从理论上解释了不同酸掺杂程度对光栅衍射效率的影响规律。论文还探索了偶氮聚电解质(PPAPE)和具有生物催化活性的β-葡萄糖苷酶(GLS)的模板静电逐层自组装。通过在聚苯乙烯胶体球表面的交替吸附,得到了固定化GLS的多层膜。对比游离酶,这种固定化酶在不同pH和温度环境下的酶活稳定性较高。研究了紫外光照对PPAPE/GLS复合膜的催化活性的影响,发现光照会引起PPAPE固定化酶活性小幅度下降。更多还原

【Abstract】 Conducting polymers (CPs) possess many unique electrical/optical properties and play an extremely important role as functional polymers. Azo polymers were well-known for their photoresponsive properties. Constructing novel composite materials such multilayers composed of both types of polymers and developing related nano/microstructures are important for potential applications in areas such as electrochromic displays, photonic crystals, micro-reactors, electro-optic modulators, and sensors. In this dissertation study, focusing on this new type of materials and structures, the methodology establishments, nano/microstructure control and electric/optical functions of the materials have been extensively investigated. The main achievements of the study are summarized as follows.Self-assembled multilayer films composed of alternate polyaniline (PANI) and azo polyelectrolytes (PPAPE, PNACN, PNANT and PNATZ) layers were fabricated through the electrostatic layer-by-layer (LBL) adsorption. The thickness contributed by each individual layer was found to be dependent on the concentrations and pH values of the PANI and azo polyelectrolytes dipping solutions. The multilayer films show interesting properties related with both components, such as conductivity, electrochemical redox, photoinduced dichroic and surface-relief-grating formation. The multilayer films possess the unique electrochromic function owning to the absorption bands of the azo chromophores and electrochromic variation of PANI. Using the azo polyelectrolytes with different hues, the electrochromic color variations can be dramatically enriched.A novel method to construct multilayer films through both the electrochemical polymerization and the electrostatic LBL self-assembly has been established. In the process, the conducting layers are built-up by the electrochemical polymerization and the polyelectrolyte layers are introduced through electrostatic adsorption. Multilayers composed of different conducting polymers (PANI, PPY and PEDOT) and polyelectrolytes (PNACN, PNANT, and PEDOT:PSS) as well as carboxyl-MWNT were fabricated by this method. Results show that the growth of multilayer films can be easily controlled by the currents and time period of the electrochemical polymerization process. By this method, multilayer composed of both CPs and azo polyelectrolytes can be feasibly fabricated, even for CPs lacking solubility in solvents.Nano/microstructures of related materials have been prepared through several methods. The honeycomb microporous conducting polymer (PEDOT) films were prepared through electrochemical polymerization of EDOT in acetonitrile and boron trifluoride ethyl ether (BFEE) solution by using polystyrene colloidal crystals as templates, which were obtained by vertical deposition on stainless steel electrodes. Uniform hollow capsules were fabricated from PTAA and a hyperbranched azobenzene-containing polymeric diazonium salt (HB-DAS) through LBL self-assembly on polystyrene (PS) colloidal spheres and removing templates after the deposition. Surface-relief-gratings of PANI were prepared through soft-lithography and studied for the optical sensor applications. The UV-vis spectra and complex refractive index of PANI change with the variations of pH and electrochemical potentials. Therefore, the diffraction efficiencies (DEs) of PANI gratings can sensing the redox and doping states. Lorentz model has been used to simulate and explain the complex refractive index changes of PANI after being treated in the different pH solutions.The LBL method has also been used in this study to prepare multilayer containing bioactive molecules. The electrostatic LBL self-assembled films composed of azobenzene polyelectrolytes PPAPE and enzyme (GLS) layers were prepared on the surfaces of PS colloidal particles. The relative activities of the immobilized GLS were measured in different pH and temperatures conditions and compared with the same enzyme in solution. The immobilized enzyme shows a wider range of environments adaption and smaller decrease of the catalysis activities. The influences of UV irradiation on enzyme activity of GLS/PPAPE-coated PS were investigated, which can result in the slight decrease of enzyme activity of immobilized GLS.更多还原