【作者】 顾大伟；

【导师】 沈临江；

【作者基本信息】 南京工业大学 ， 材料物理与化学， 2004， 硕士

【摘要】 导电聚苯胺由于合成原料易得、制备方法简单、具有较好的环境稳定性以及较高的电导率而成为导电高聚物领域的研究热点。多年来大量的系统研究发现，导电聚苯胺的分子结构、物理化学性能强烈依赖于合成方法与合成条件。 本文的研究目的是探索在高压条件下合成导电聚苯胺的方法，进而研究高压条件下的合成条件对导电聚苯胺性能的影响。我们创造性的提出了一种在高压条件下合成PANI薄膜的新方法——高压原位聚合法。利用该方法我们成功合成出了导电PANI薄膜样品。与常压下制备的样品相比，高压条件下合成的PANI薄膜样品展现出很多极有意义的特征。主要有：纳米网状结构(nano-network)的表面形貌、更为平整的薄膜表面、高出一个数量级的电导率，和明显的共轭度提高。 本文对不同的高压合成条件，就PANI薄膜样品的一些主要性能进行了探讨。我们发现在150 MPa至600 MPa的高压条件下，均可以合成出具有纳米网状结构的PANI薄膜样品，而且样品的极化子吸收峰随压力增加出现红移现象。这表明样品的共轭度得到了明显的提高。PANI薄膜样品的膜厚与反应压力紧密关联，呈现一种π形的关系。即常规条件下制备的PANI薄膜样品厚度最小，为45 nm。而在150-450 MPa高压范围内制备的PANI薄膜样品的厚度基本上不发生改变(～100 nm)。当反应压力进一步增加到600 MPa时，样品的厚度又降为70 nm。实验结果还表明高压条件下合成的样品的表面粗糙度要明显低于常规样品。 在常压至600 MPa反应条件下，样品的电导率随着合成压力的提高而增加。在合成压力为600 MPa时，高压原位聚合法制得的PANI薄膜样品达到了16.9S／cm。运用导电高聚物“金属岛”理论模型，我们认为一方面高压条件下所获得的PANI纳米网络状结构中“金属岛”占据的体积比常压合成的颗粒状薄膜中“金属岛”占据的体积大。其次，高压条件提高了金属岛间的接触概率，有利于“金属岛”之间的载流子跃迁更容易发生。这两因素共同导致了高压原位聚合法制备的PANI薄膜样品电导率出现了数量级的提高。 我们对高压原位PANI聚合反应进行了动力学研究。在高压条件下，薄膜生长过程中诱导期与氧化聚合期均明显缩短。根据一般的吸附规律和化学反应动力学原理，我们从实验结果得出:高压原位PANI聚合过程中，高压条件增加了活性单元的吸附速率，提高了聚合反应速率常数K。 本文提出了一个高压条件下的PANI薄膜生长模型。在高压条件下，PANI分子沿基片方向的生长要优于基片垂直方向的生长，这是一种二维生长模式，也是导致纳米网状结构的根本原因。 在相同的高压条件下，样品的共辆程度与反应时间存在着一定的关系。在反应初期，反应时间的延长会引起PANI分子链上的共扼大:键的重叠程度的增加。在反应过程的后期，随着反应时间的进一步加长PANI分子链上醒环与氮原子的共扼作用减弱。 在本文的最后我们给出了高压条件下使用不同质子酸作为掺杂剂合成PANI薄膜样品的一些实验结果。质子酸对高压条件下合成样品性能的影响与常规样品满足的基本规律是相似的。更多还原

【Abstract】 In the past years, the research of polyaniline (PANI) has been a hot special topic. This is because of many benefits of PANI, such as low cost, easier preparation, excellent environmental stability, and higher conductivity etc. Many systemic studies results indicate that the molecular structure, physical and chemical properties of PANI depend on the synthesis method and reaction conditions, intensively.The aim of this work is to explore a new synthesis of PANI, in which a high pressure is applied, and to investigate the effect of high pressure on the properties of PANI. The new method is "In-situ polymerization under high pressure", abbreviated to ISPHP, that created by us firstly. Our experimental results show that the new method is suitable for PANI film. Comparing to those PANI films obtained at ambient pressure, our samples exhibit many interesting characterizations, including nano-network of micro-morphology, lower rough surface, higher conductivity, and higher conjugate degree.In this thesis, we firstly investigate the main properties of PANI films prepared under different high pressure. Between 150 MPa and 600 MPa high-pressure ranges, it is easy to synthesize PANI film with nano-network. In addition, an obvious Red-shift of polaron band in UV-Vis spectra is observed. The Red-shift indicates that the conjugate degree of our samples is increased. The thickness of the films by ISPHP is strongly related to applied pressure. The thickness of PANI films obtained at atmosphere is the lowest (about 45 run), while it increases to -100 nm in the pressure range of 150 - 450 MPa and drops to about 70 nm as applied pressure at 600 MPa. SEM shows that the surface of the films obtained by ISPHP is slicker than those synthesized at ambient pressure.From ambient pressure to 600 MPa, the conductivity of films increases as increasing the pressure. At 600 MPa, the conductivity of film by ISPHP is as high as 16.9 S/cm. One hand, the volume of "Metallic Island" in PANI nano-network is larger than those in granular films according to the metallic island model. On the other hand,high pressure improves the contact between the metallic islands, which is benefit to the hopping of carry charges. Both effects result in a distinct increase in conductivity.We also study the thermal kinetics for ISPHP. In the case of high pressure, the induction period and polymerization of growth of film are largely contracted. Base on the absorption law and chemical thermal kinetics, we conclude that applied high pressure improves the rate of absorption of cation radicals and the reaction rate constant K.Also, a growth model of PANI film for ISPHP is established. Under high pressure, the chains grow easily alone the surface of the substrate than perpendicular direction. This is the main reason why the nano-netwok is formed in ISPHP.In the case of high pressure, there is a relationship between conjugate degree and reaction time. In initial progress, the increase of reaction time results in the overlap of conjugate it bond in the chains of PANI. In later period in synthesis, the interaction between quinone ring and N atom in the PANI chains decreases as reaction time increases further.Finally, we investigate the influence of proton acid as dopant in ISPHP to PANI films. The effect of proton acids on the properties of PANI obtained by both ISPHP and normal method is similar.更多还原