摘要
准一维的碳纳米管是一种潜在的优良气敏材料,它具有很大的表面-体积比和丰富的孔隙结构,对一些气体分子有很强的吸附能力。同样,聚苯胺也具有一定的气敏响应特性,掺杂聚苯胺后的碳纳米管,其气敏特性有显著提高。基此,本论文主要做了以下的研究：
论文中采用了较为简单的原位聚合法,制备出了本征态聚苯胺。并利用介电泳方法可实现对碳纳米管的定向操控的特性,通过优化控制碳管所在交流电场的幅值、频率及时间等参数实现在叉指电极间定向排布碳纳米管、聚苯胺纤维膜,测试了两种材料对氨气的响应特性,从响应时间、恢复时间、线性度等参数分析其特点。
同时,本文重点介绍了基于聚苯胺及多壁碳纳米管复合材料的氨气传感器的制备与测试,使用原位聚合法使苯胺单体以碳纳米管为核心进行聚合反应,运用介电泳法制备多壁碳纳米管/聚苯胺气敏复合膜传感器。该传感器对10ppm氨气的响应灵敏度为3.4,响应时间15s,而对比实验中聚苯胺膜传感器的灵敏度为1.9。实验结果表明,由于碳纳米管在介电泳过程中构建的大比表面积纳米三维结构和优良的导电率,纳米复合材料的微观结构和导电性能都得到大幅改善,从而使得复合物具有相对于本征碳纳米管和聚苯胺膜更好的气敏特性。
此外,我们还采用直接分散法对碳纳米管进行聚苯胺掺杂,实验结果证明,基于直接分散法制备的碳纳米管聚苯胺混合物气体传感器的响应为2.837。与之前本征碳纳米管制作的气敏传感器相比,响应时间大大缩短,恢复时间略大于之前的传感器,并且直接分散法制作的传感器在1000s左右时能完全恢复到之前的位置,而本征碳纳米管却不能。
实验进一步证明,掺杂聚苯胺的碳纳米管有着更好的气敏应用前景。该制备方法克服了本征态碳纳米管气敏特性低的缺陷,增强了聚苯胺纳米结构特性,提升了复合材料对氨气的气敏响应特性。
Carbon nanotubes(CNTs) has porous microstructure and high surface area, so has strong absorption for some gas, which makes it a promising future as sensitive material. It is found that polyaniline(Pani) also has a certain gas sensor response characteristics. The characteristics of gas sensors based on carbon nanotubes doped Fani is significantly higher. Have this in mind, we do the following works:
In this paper, we prepared polyaniline using the method of in-sute polymerization. And we control the ordered arragement of carbon nanotubes and Pani by using electrophoresis (DEP).The parameters we optimize are amplitude, frequency and time of the electric field. We also test the gas sening characteristics to ammonia of the two materials, and we certify the conclusion from response time, recovery time, linear degrees.
Carbon nanotube and Polyaniline composite for gas sensing were investigated in this paper. Pani coated multi-walled carbon nanotube (MWNT) was synthesized by means of in-sute polymerization and dielectrophoresis. The nano-composite sensor showed a 3.4 reversible resistance change to lOppm NH3 with a response time of 15s while the sensitivities of Pani film sensor is 1.9 in the contrast experiment. The results indicate that the nano-composite sensitivity and sensing dynamic are improved due to the nanostructure with ultra-high surface-volume ratio and good conductivity. The mechanism of sensitivity to NH3 of the sensor was also discussed.
In addition, we also use the method of direct scattered to prepare carbon nanotubes doped polyaniline.The mixed gas sensor response is 2.837 to ammonia in our experiment.And compared to pure CNT,the response time shortens greatly, the recovery time is just slightly longer, and the desorption is better.
In conclusion,the gas sensor based on the CNT doped Pani has a better application prospect. The methods we use not only overcome the low defects of CNT gas scnsors,but also enhance the nano structure characteristics of polyaniline, which makes the composite material a star material for ammonia detection.
引文
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