【作者】 陈飞；

【导师】 刘鹏；

【作者基本信息】 兰州大学 ， 高分子化学与物理， 2014， 博士

【摘要】 本研究论文主要致力于导电聚苯胺胶态纳米粒子的合成与应用研究。在论文开始部分,综述了聚苯胺的化学结构、合成方法、掺杂机制和导电聚苯胺的性能特征,阐述了导电聚苯胺纳米复合材料的应用研究现状与导电聚苯胺复合材料在工业应用中普遍存在的问题——如何提高聚苯胺的可容性与可加工性。论文的研究部分主要包括以下四个方面：首先,制备了可加工型的聚苯胺胶态纳米粒子。以磷酸酯化聚乙烯醇为稳定剂和共掺杂剂制备了具有良好导电性能和水相分散稳定性的聚苯胺/磷酸酯化聚乙烯醇(PANI/P-PVA)胶态纳米粒子。以过硫酸铵为氧化剂,磷酸酯化聚乙烯醇为表面活性剂(聚合物稳定剂),在0.5M的HC1水溶液中,通过化学氧化聚合制备了聚苯胺/磷酸酯化聚乙烯醇胶态纳米粒子及其水相分散液。通过透射电子显微镜、红外谱图、X-ray粉末衍射、热失重分析和电导率测试等分析与测试方法,研究了聚苯胺/磷酸酯化聚乙烯醇纳米粒子的形貌、微观结构、热性能和导电性能。结果表明,在该体系中,磷酸酯化聚乙烯醇不仅作为聚合物稳定剂影响聚苯胺纳米粒子的形貌和粒子的水相分散性能,而且作为共掺杂剂对掺杂聚苯胺的导电性能有明显作用。当磷酸酯化聚乙烯醇用量为40wt%时,可得到球状聚苯胺/磷酸酯化聚乙烯醇胶态纳米粒子,其干态粉末的电导率为6.94S/cm,且胶态纳米粒子在水相的再分散稳定性能良好。其次,通过无皂乳液聚合将丙烯酸类单体聚合生成聚丙烯酸酯,对聚苯胺/磷酸酯化聚乙烯醇胶态纳米粒子进行囊化包覆,制得聚苯胺/聚丙烯酸酯复合粒子及其导电薄膜。采用透射电子显微镜和扫描电镜分析了复合粒子和复合膜的表面形貌,用X射线光电子能谱对复合粒子进行了表面元素分析,结果表明：聚丙烯酸酯已经被引入聚苯胺纳米复合粒子的表面,但是聚丙烯酸酯并未将聚苯胺纳米复合粒子完全包覆。聚丙烯酸酯又具有良好的成膜性能和机械性能,对提高聚苯胺复合材料的机型性能起到决定性作用,当丙烯酸酯的含量为50.93wt%时,制得的聚苯胺纳米复合材料的片状颗粒的电导率0.41S/cm,薄膜的电导率为0.05S/cm,杨氏模量为1.6MPa,拉伸强度为17.6MPa,断裂伸长率为125%。该复合材料可用于电磁屏蔽材料和静电消除材料。再次,以导电聚苯胺/磷酸酯化聚乙烯醇胶态纳米粒子为功能填料,以水性环氧树脂为涂料基质,配制了聚苯胺水性防腐涂料。对涂层的机械性能进行评价之后,通过浸泡试验和盐雾试验评估了涂层对低碳钢的腐蚀防护效果,并通过电化学交流阻抗法量化分析评价了该水性防腐涂料的碳钢腐蚀防护性能。当导电聚苯胺/磷酸酯化聚乙烯醇胶态纳米粒子的含量为2.5wt%时,涂层具有最佳的机械性能和最好的腐蚀防护作用(试样经过30天的盐雾试验后,试样表面的低频阻抗依旧高于107Ω cm2,涂层依旧保持较好外观)。用X射线光电子能谱和扫描电子显微镜对涂层-碳钢基体界面进行分析研究,探讨了可能的腐蚀防护机理：导电聚苯胺粒子与基体界面相互作用,形成三氧化二铁钝化膜和铁-磷酸盐二次钝化膜,导电聚苯胺/磷酸酯化聚乙烯醇胶态纳米粒子的良好水相分散性有助于涂层的内部结构更为紧密,从而提高涂层的机械性能,同时,磷酸盐的存在也有利于提高涂层与基材的附着力。最后,制备了具有高比电容和电化学稳定性的石墨烯/聚苯胺复合材料。采用原位聚合,将苯胺氧化聚合到氧化石墨烯表面,得到氧化石墨烯/聚苯胺复合材料,再用水合肼同时还原氧化石墨烯和聚苯胺,得到具有大比表面积,高电导率和稳定电化学特性的石墨烯/聚苯胺复合材料。透射电子显微镜、拉曼光谱、热失重分析和电导率测试分析了复合材料的形貌、微观结构、热性能与导电性能；采用循环伏安法与恒电流充放电技术测试了复合材料的电化学性质。结构表明,聚苯胺成功的附着到氧化石墨烯表面,被水合肼还原后,依旧有足量的聚苯胺存留在石墨烯表面。热失重分析与循环伏安法测试表明经还原后的石墨烯／聚苯胺复合材料具有良好的热稳定性和电化学活性。从微观角度来看,经水合肼还原后的石墨烯作为电子接受体的同时,又作为平衡离子对聚苯胺的中间氧化态起到稳定作用。循环伏安法和恒电流充放电测试结构表明该复合材料具有较高的比电容和良好的电化学稳定性,可用于超级电容器电极材料。更多还原

【Abstract】 Among the available intrinsically conducting polymers, polyaniline is found to be the most promising because of its ease of synthesis, low cost monomer, tunable properties, and better stability compared to other intrinsically conducting polymer. However, the main problem associated with the effective utilization of polyaniline is inherent in their lower level of conductivity compared to metal, and their infusibility and poor solubility in all available solvents. In order to overcome these shortcomings, we proposed a novel idea in the preparation of the colloidal PANI nanoparticles, employing partially phosphorylated poly(vinyl alcohol) as both the stabilizer and co-dopant for the first time. And the applications of the prepared PANI nanoparticles were explored:Firstly, the polyaniline/partially phosphorylated poly(vinyl alcohol) nanoparticles were prepared by the chemical oxidative dispersion polymerization of aniline monomer in0.5M HC1aqueous media with the partially phosphorylated poly(vinyl alcohol) as the stabilizer and co-dopant. The prepared nanoparticles were characterized by transmission electron microscopy, Fourier transform infrared, thermal gravimetric analysis, electrical conductivity measurement, and re-dispersion stability testing. All the results were compared with the properties of the conventional polyaniline in the emeraldine salt form. It was found that the feeding ratio of partially phosphorylated poly(vinyl alcohol) obviously affected the morphology, re-dispersion stability and electrical conductivity of the prepared nanoparticles. When the feeding ratio of phosphorylated poly(vinyl alcohol) is40wt%, the polyaniline/partially phosphorylated poly(vinyl alcohol) nanoparticles showed spherical shape with good uniformity, significant re-dispersion stability in aqueous media, and good electrical conductivity (6.94S/cm).Next, conducting polyaniline/partially phosphorylated poly(vinyl alcohol)/polyacrylate composite nanoparticles were prepared by the encapsulation of the polyaniline/partially phosphorylated poly(vinyl alcohol) nanoparticles with polyacrylate via the emulsifier-free seeded emulsion polymerization. Transmission electron microscopy, scanning electron microscopy and X-ray photoelectron spectra analysis of the prepared composite nanoparticles showed that the polyaniline/partially phosphorylated poly(vinyl alcohol) nanoparticles were successfully encapsulated with the polyacrylate. With the increasing of the feeding ratio of acrylate monomers, the diameter of the polyaniline/partially phosphorylated poly(vinyl alcohol)/polyacrylate composite nanoparticles increased and their electrical conductivity decreased. Cyclic voltammogram revealed that the composite nanoparticles were electroactive. When the content of polyacrylate is50.93wt%, the prepared composite shows a electrical conductivity of0.41S/cm in pellet and0.05S/cm in powder. And good quality films with appreciable Young’s modulus (1.6MPa), tensile strength (17.6MPa), and elongation at break (125%) could be obtained from the prepared composite nanoparticlesThirdly, the waterborne corrosion protection polyaniline contained coatings was developed. The conducting polyaniline/partially phosphorylated poly(vinyl alcohol) spherical nanoparticles with significant dispersibility in aqueous media were prepared by the chemical oxidative dispersion polymerization in the presence of the partially phosphorylated poly(vinyl alcohol). Then the polyaniline contained coatings with different polyaniline/partially phosphorylated poly(vinyl alcohol) contents were prepared, employing waterborne epoxy resin as the matrix. The corrosion protection property of the polyaniline/partially phosphorylated poly(vinyl alcohol) contained coatings on mild steel was investigated by the salt spray test and electrochemical impedance spectroscopy technique in3.0wt%NaCl aqueous solution. The results indicated that the waterborne polyaniline/partially phosphorylated poly(vinyl alcohol) contained coatings could offer the high protection since the impedance values are remained at higher than107Ωcm2after30days of the salt spray tests. All the results were compared with these of the waterborne coatings containing the polyaniline nanoparticles in the emeraldine salt form and the protection mechanism was also proposed.Finally, a simultaneous reduction of graphene oxide/polyaniline flake composites by coating polyaniline onto graphene oxide sheets was developed to prepare the novel electrode materials for the high performance supercapacvitors. The graphene oxide/polyaniline composites were prepared by the chemical oxidation polymerization of aniline in the aqueous dispersion of graphene oxide. Then the reduced graphene oxide/Polyaniline composite flakes were obtained by the chemical reduction of the graphene oxide/polyaniline composites, with hydrazine hydrate as the reducing agent. Transmission electron microscopy, thermal gravimetric analysis and cyclic voltammogram were employed to investigate the surface, thermal property, and electroactivity of the samples. The results revealed that polyaniline was polymerized on the surface of graphene oxide sheets and after reduction there was still thin polyaniline coating on reduced graphene oxide sheets. The results also indicated that both the thermal stability and the electroactivity of the reduced graphene oxide/polyaniline flakes were distinctly enhanced than those of the graphene oxide/polyaniline composites. In the reduced graphene oxide/Polyaniline flakes, reduced graphene oxide played a dual role:as electron acceptor and also as a counterion to stabilize an atypical intermediate oxidation state of polyaniline. When hydrazine hydrate was introduced in to the system, the reduction of graphene oxide to reduced graphene oxide was taken place accompanied by the reduction of the polyaniline emeraldine salt to polyaniline leucosalt, and reduced graphene oxide subsequently played a role as a redoping agent and doped the polyaniline leucosalt to polyaniline emeraldine salt, which resulted in the high electroactivity of the reduced graphene oxide/polyaniline flakes. Cyclic voltammograms and galvanostatic charge-discharge technique indicated that the prepared graphene/polyaniline composites have high specific capacitances and good cycling stability, which are advantageous for their applications as electrode materials for supercapacitors.更多还原