非共轭有机高分子PEO的气敏性能研究

【作者】 陈春姣；

【导师】 唐新村；

【作者基本信息】 中南大学 ， 有机化学， 2008， 硕士

【摘要】 目前科学技术迅猛发展,在为人类生活提供极大方便的同时,也对生态环境造成了严重的污染,有毒气体和可燃性气体随时威胁着人类的生命财产安全。随着人类对生存环境要求的提高,对可燃气体和毒性气体的检测、监控、报警的要求也就越来越高。有毒气体和可燃气体的检测首先依赖于高品质的气体传感器的开发。但现在在气体传感器材料的研究及开发上存在的主要问题是高灵敏度、常温化、快速响应、好的选择性以及长期稳定性不能同时满足。因此提高气敏材料的灵敏度、选择性及长期稳定性以及降低工作温度、缩短响应恢复时间等成为近年来国内的研究重点和热点。现在国内关于气体传感器材料的研究主要是金属氧化物类无机半导体气敏材料,如SnO₂、Fe₂O₃、ZnO、TiO₂,以及高分子有机半导体气敏材料。高分子有机半导体气敏材料一般分为共轭高分子气敏材料与高分子复合气敏材料,如聚吡咯、聚苯胺、酞菁、聚噻吩以及高分子/碳黑复合物、聚苯胺/聚乙烯醇复合物等。无机半导体的气敏性研究在国内外已有广泛的报道,但其存在着温度高（350～450℃）、耗能高、有安全隐患、选择性不好等缺陷。与无机半导体材料相比,高分子有机半导体材料具有很多的优点。价格低廉,制作简单,在制备过程中不需要超净室和高温处理,最重要的是可以在室温下使用,解决了易燃易爆气体的安全隐患问题。本文研究的是聚环氧乙烷PEO的气敏性能。PEO具有良好的水溶性,容易加工成型,而且毒性很低。PEO作为一种非共轭的绝缘高分子材料,与共轭高分子材料形成高分子复合气敏材料在国外文献已有报道。而单独研究不具有共轭性质PEO的气敏性能,国内外在这方面的研究也未见报道。本文用溶液成膜法制备了PEO薄膜以及PEO+I₂的薄膜,研究其在室温下对醇类气体和有机酸类气体的气敏性能,包括灵敏度、选择性、响应和恢复时间以及稳定性。研究结果表明,PEO对有机醇类和酸类有很好的气敏性能。通过一系列的形貌表征手段来观察PEO薄膜在不同气氛下的形貌变化,包括扫描电镜、原子力学显微镜、偏光显微镜,这些测试发现PEO在有机醇类和酸类气体中,PEO发生了溶胀现象,其球晶变大。从FTIR谱图中,我们可以看出PEO在甲醇气体中发生了缔合。循环伏安对比测试发现PEO在有机酸中无氧化还原反应的发生。交流阻抗测试结果表明,PEO在有机酸和醇类气体中,其导电行为为离子导电。希望通过掺杂来进一步提高PEO的气敏性能,研究了PEO掺杂单质碘的气敏情况,结果表明,掺杂后的PEO气敏性能,并没有得到改善。通过一系列的形貌表征测试手段来观察PEO+I₂薄膜,研究表明PEO+I₂薄膜在有机醇类气体中,其发生了溶胀现象,但单质碘并没有在里面形成一个导电网络。更多还原

【Abstract】 In recent years,with the fast development of science and technology, it provides tremendous convenience to human beings.But at the same time,it has seriously polluted the enviroment.Owing to the toxic and flammable gases threat to our health and wealth,human beings call for a high-qualiy environment.So it becomes more and more important in the study of gas sensor to detect and inspect the toxic and flammable gases. Now the main problem in the research and development is that high-sensitivity,normal-temperature,fast-response,good-selectivity, extended-stability can’t meet at the same time.Recently,the research and development focus on how to enhance the sensitivity,selectivity and stability,reduce the temperature,and shorten the response-recovery time.Now,a lot of work has been done in the research of MOS in our courtry,such as SnO₂、Fe₂O₃、ZnO、TiO₂,and organic polymer conductors, including the conjugated polymers and polymer composites,such as polypyrrole,polyaniline,phthalocyanin,polythiophene,composite of polymers with carbon black,composite of poly（vinyl alcohol）with polyaniline,etc.Inorganic semiconductors have recently attracted a great deal of attention for application in gas sensors.But there are still many disadvantages,such as high temperature（350～450℃）,energy-waste, unsafety,bad-selectivity,etc.The organic polymer conductor has more advantages when compared with the inorganic semiconductors,such as low-price,and easy-made.When prepared,we don’t need super clean room and high temperature treatment,what is more important,it can operate in room temperature avoiding the unsafety of flammable gases.In this work we investigate the properties of gas sensors made from PEO with good water-solubility,easy-shape and low-toxicity.As an unconjugated and insulated polymer,there are several reportes about its composites with conjugated polymers as gas sensing materials in foreign literature.However,there is little report about the application of pure PEO in gas sensor.In the paper,we prepare the films of PEO and PEO doped with I₂ by solution and study the gas sensitivity of alcohols and organic acids in room temperature,including the sensitivity,selectivity, response-recovery time and stability.The corresponding morphology characterizations including SEM, AFM and Polarizing Microscope show that the spherulites of PEO grow and swell when the film of PEO dipping into the vapors of alcohols and organic acids.Hydrogen bond is formed when PEO dipped in methanol which is cleaty shown m the FTIR.And from the cyclic voltametry spectra,we fred there is no oxidation-reduction reaction when the thin-film of PEO dipped in the organic acids.Finally,the mechanism of the ionic conduct is confirmed according to the analysis of the impendance spectra.Furtherly,we stndy the gas=sensing properties of the film PEO doped with I₂.However,the gas-sensing properties don’t improved when compared with the PEO.Morphology characerization show that the film PEO doped with I₂ becomes swelling and there is no observation of a continuous conduct channel of I₂.更多还原