【作者】 孙萍；

【导师】 蒋亚东；

【作者基本信息】 电子科技大学 ， 光学工程， 2010， 博士

【摘要】 二十一世纪,全球各国都将可持续发展作为所面临的首要问题而给予了高度关注,环境污染是其中最主要的困难之一。各国对各种有毒有害气体的探测,对大气污染、工业废气的监控以及对人居环境质量的检测都提出了更高的要求。因此,发展低成本可携带的有毒有害气体传感器及阵列,对于环境污染的源头进行监控具有重要的意义。在众多气体传感器中,质量敏感型气体传感器结构紧凑、工艺性好、成本低、适宜于批量生产等优点而被广泛应用于有毒有害气体的检测中。但质量敏感型元件本身对气体或蒸气不具有选择性,其作为化学传感器的选择性仅仅依赖于表面敏感膜的性质。因此本文以质量敏感型传感器元件为基础,合成新型气体敏感材料聚炔和超分子材料,以及基于聚炔的有机无机复合材料,制备有毒有害气体传感器单元,并测试其对可燃气体甲烷和有毒气体挥发性有机化学物质(VOC)的敏感特性,在此基础上建立质量敏感型气体传感器阵列,与现有传感器组成的阵列实现有毒有害气体的定性定量识别。其主要内容包括以下几个方面:1.通过对质量敏感型传感器的质量敏感效应、敏感薄膜与气体分子的吸附特性以及气体分子在敏感薄膜上吸附作用的线性溶剂化能关系等的研究,建立敏感机理的物理化学模型。用多物理场耦合模型实现了对声波气体传感器的仿真,利用仿真过程大大减少了原型机的实验量,缩短传感器开发周期,降低开发成本。2.用Stelle耦合反应合成含苯基的聚炔材料聚-2,5-二甲氧基乙炔苯(PDMEB),用Sonogashira耦合反应合成含稀有金属的苯基聚炔材料聚-(2三乙烷化磷-铂-二乙炔苯)(Pt-DEB),并采用旋涂方法在质量敏感型传感器元件上成膜,用以制备基于聚炔类敏感材料的传感器单元,测试该传感器单元对可燃气体甲烷和有毒气体VOC的气体敏感特性。实验结果发现室温下PDMEB对结构牢固的甲烷有较明显的气敏特性,表面形貌分析发现PDMEB的表面存在有孔洞,为甲烷气体分子提供了较多的吸附位及较好的吸附/脱附条件,红外光谱分析发现PDMEB还和甲烷存在一定的结合,从而使其对甲烷有气敏特性。室温下Pt-DEB对VOC的气敏响应明显优于PDMEB,包括较好的基频稳定性,很好的重复性,气敏响应的线性化等。Pt-DEB对VOC的探测极限可达1ppm。结合Pt-DEB的表面形貌分析其敏感机理主要源自于溶胀现象。3.用廉价的香草醛为原料,采用改进的二次三聚合的方法合成超分子材料穴番-A,用静电喷雾的成膜方法在质量敏感型传感器元件上制备成气体传感器单元,测试其对甲烷的气敏特性并研究温湿度对传感器的影响。实验发现基于穴番-A的声波型传感器对甲烷有较好的气敏特性,探测极限可达0.05% (v/v)。采用分子力学的方法初步分析穴番-A对甲烷敏感的原因主要来自于主体分子对客体分子的范德华引力。4.在合成PDMEB聚合物的基础上原位合成了PDMEB/SnO2和PDMEB/In2O3有机无机纳米复合敏感材料,旋涂在质量敏感型传感器元件上用以制备气体传感器。实验发现SnO2和In2O3纳米粒子的加入不仅改变了聚合物的形貌,改善了成膜特性,还增强了室温下聚合物PDMEB对甲烷的灵敏度。结合气体传感器的实时频率响应曲线,分析甲烷气体在敏感膜上的吸附和脱附动力学理论,推导甲烷气体在聚合物敏感膜PDMEB以及其有机无机敏感膜PDMEB/SnO2和PDMEB/In2O3上的吸附速度和脱附速度,加入SnO2和In2O3无机纳米粒子的传感器对1000ppm甲烷的吸附速率常数相等,均为0.0145,大于纯聚合物PDMEB对1000ppm甲烷的吸附速率常数(0.0138),它们两个的脱附常数也都高于纯PDMEB。无机材料的加入还改变了PDMEB对VOC气敏的选择性,PDMEB/SnO2对醇类有较好的气敏特性,而PDMEB/In2O3则对四氢呋喃有较好的气敏特性,它们对氯仿和丙酮都没有气敏特性。5.采用层层自组装的方法将碳纳米管有机无机复合材料成膜在质量敏感型传感器元件上制备传感器单元,测试气敏特性。并比较了不同溶剂分散对气敏的影响,实验结果发现气敏特性出现溶剂功能化效应,即用某种溶剂分散的碳纳米管对该溶剂的蒸汽呈现很好的气敏特性,这对改善传感器的选择性具有一定的意义。而在聚阳离子PDDA和聚阴离子PSS的静电作用下自组装成膜的碳纳米管则对氨蒸汽呈现很好的气敏特性,温度对该气敏响应的影响符合阿累尼乌斯方程的负温度依赖关系。6.建立质量敏感型声表面波气体传感器阵列,以及现有的半导体式和催化燃烧式气体传感器组成阵列,结合数据处理方法实现对可燃性气体甲烷和氢气以及常见有毒气体VOC的定性识别和定量分析。更多还原

【Abstract】 Countries around the world pay great attention to the sustainable development in the twenty-first century. Environmental pollution is one of the most important difficulties. There is a critical need for toxic and harmful gas detection such as atmospheric pollution, industrial emissions monitoring and the detection of the quality of human settlements. Therefore, the development of low-cost portable gas sensor and array is of great significance. Among gas sensors, mass-sensitive gas sensors have been widely used in the detection of toxic and harmful gases because of their compact structure, good technology, low cost, suitable for mass production and so on. However, the selectivity of the mass-sensitive gas sensors depends on the type of the surface sensitive membrane. The dissertation focused on the mass-sensitive gas sensors. Especially, a great deal investigations have been done on the sensitive materials such as poly-enes, supramoleculars and organic inorganic composites. The mass-sensitive gas sensors deposited these sensitive materials are tested for the gas sensitivity to the flammable methane gas and toxic gas volatile organic chemicals (VOC). Furthermore, the application of surface aoustive gas sensor array to qualitalive and quantitative analysis of VOC was also described. The main research contents were as follows:1. Study on the working principle of mass-sensitive gas sensor. Establish the physical and chemical model of sensitive mechanism based on the mass-effect and the adsorption characteristics of gas on the senstive membrane. The linear solvation energy relationship (LSER) has been developed to describe and quantify these various interactions. Simulate the mass-sensitive gas sensor based on COMSOL multiphysics software. The simulation significantly reduces the amount of prototype experiments, sensor development cycle and development costs.2. Poly-2, 5-dimethoxyethynylbenzene (PDMEB) was synthesized according to stelle coupling reaction, while poly-(bistriethylphosphine)-platinum-diethynylbenzene (Pt-DEB) was synthesized by dehydrohalogenation reaction (Sonogashira coupling reaction). The polymer films were deposited onto the surface of acoustic devices by spin-coating method to fabricate gas sensors. Sensitive properties of them to methane and VOC have been studied. It was found that the PDMEB based acoustic sensor has good sensitivity to methane at room temperature. The surface morphology revealed that the existence of holes on the PDMEB surface provided adsorption sites for methane gas molecules. The infrared spectra confirmed there was a certain combination of PDMEB in methane gas. Pt-DEB based acoustic sensor has better sensitivity to VOC than PDMEB based acoustic sensor such as reversibility, reproducibility, and linear sensitivity at room temperature. The low detection limits about 1.0 ppm to trichloromethane was found. The sensing mechanism is due to the swelling phenomenon.3. Supramolecular cryptophane-A was synthesised from vanillyl alcohol using a double trimerisation method and deposited on acoustic device via electrospray method to fabricated gas sensor. The sensor was exposed to various concentrations of methane gas. The influence of humidity was also examined. The sensor’s response showed that it is sensitivity to methane gas. A fast response and recovery was observed at room temperature. Detection limit for methane is 0.05% (v/v). The mechanism of CH4 interactions with cryptophane-A arises from size complementarity and efficient van der Waals interactions.4. Inorganic nanoparticles SnO2 and In2O3 were dispersed in PDMEB using an in-situ synthesis technique to prepare organic-inorganic nanocomposites PDMEB/SnO2 and PDMEB/In2O3. The nanocomposites were spun-coated on acoustic devices to fabricate gas sensors. It was found that SnO2 and In2O3 nanoparticles not only changed the morphology of PDMEB and improved the film properties, but also enhanced the sensitivity to methane at room temperature. The adsorption and desorption curves were carefully analysed using kinetic theory for the resonse of methane gas on PDMEB and PDMEB/SnO2 and PDMEB/In2O3 nanocomposites coatings. The adsorption constants of PDMEB/SnO2 and PDMEB/In2O3 nanocomposites to 1000 ppm methane are equal. The value is 0.0145, which is more than the value of pure PDMEB (0.0138). The desorption constants of PDMEB/SnO2 and PDMEB/In2O3 nanocomposites are also more than of pure PDMEB. The inorganic nanoparticles changed the selectivity of the polymer to different VOC. PDMEB/In2O3 showed good sensitivity to THF, but PDMEB and PDMEB/SnO2 had good sensitivity to alcohol (methane, ethane and isopropyl alcohol). All of them had no sensitivity to acetone and chloroform. 5. Carbon nanotubes (CNTs) based organic-inorganic composite was deposited on acoustic devices through layer-by-layer self-assembly method to fabricate gas sensors. Dispersed in different solvents, the CNTs showed different response. They showed better gas-sensing properties to the VOCs whose polarity is similar to the polarity of the solvent, which was mentioned as solvent-functionalized CNTs. This has a certain significance to improve the selectivity of CNTs based sensors. The layer-by-layer assembly carbon nanotube thin film used PDDA and PSS as polycation and polyanionic, respectively. It had has good sensing properties to ammonia at room temperature. The senosr response was decreased when the temperature increased, which is in accordance with Arrhenius equation.6. Establish surface acoustic wave (SAW) based gas sensor array and commercial semiconductor-type and catalytic sensor array. The SAW array is used to discriminate and quantify VOC with data processing methods. The commercial sensor array is used to qualitative and quantitative analysis among combustible gas methane and hydrogen.更多还原