基于有机多孔聚合物的湿度传感器的研究

发布时间：2018-06-07 07:59

本文选题：湿度传感器 + 多孔聚合物　；参考：《吉林大学》2016年博士论文

【摘要】：湿度是自然环境中普遍存在的物理量,湿度传感器是能够将环境湿度转化为相应可测量电信号的器件。湿度传感器的基本原理是基于湿度敏感物质与水分子之间的相互作用引起材料导电能力的变化,因此敏感材料是决定湿度传感器性能的关键。实用化的电阻型湿度传感器的双亲性聚合物通常由疏水性的主链和带有极性基团的亲水性支链构成,通过极性基团对水分子进行吸附,电离产生可以自由移动的导电粒子。当环境湿度发生变化时,吸附水分子的量相应发生变化,从而引起导电粒子浓度的变化,通过测试敏感膜的导电特性就可以实现对环境湿度的监测。双亲性聚合物材料在较高相对湿度(80%RH)下长期工作时,由于亲水性基团和水分子之间的强相互作用,容易引起亲水性基团的聚集。因而吸附水分子较多时可能引起敏感物质的部分溶解而发生流失,对元件的稳定性产生非常严重的影响。在本论文中,以提高湿度传感器的高湿稳定性为目标,发展了新型多孔聚合物湿敏材料,通过物理共混和化学修饰两类不同的方法构筑了多种多孔聚合物复合湿敏材料和双亲性多孔聚合物湿敏材料,并获得了一系列具有优异特性的湿度传感器。主要内容如下:(1)采用付克烷基化反应制备出大孔聚合物P3HBA,通过物理共混的方法将湿敏活性物质Li Cl装载到P3HBA的孔道中,获得了湿敏特性优异的Li Cl/P3HBA复合敏感材料。通过比较引入湿敏活性物质Li Cl前后材料湿敏特性的差异,深入研究了Li Cl在湿度敏感机制中的作用,归结为两个方面:首先,Li Cl的引入增强了复合材料的亲水能力,使其在低湿环境中也能吸附一定量的水分子因而引起湿敏元件阻抗的变化;其次,在高湿环境中,Li Cl能在吸附的液态水层中电离出离子参与导电,使湿敏元件的阻抗进一步减小。(2)利用溶剂热法合成了微孔聚合物POF,通过物理共混的方法将湿敏活性物质Li Cl装载到POF的孔道中制备湿敏特性良好的Li Cl/POF复合湿敏材料。通过与Li Cl/P3HBA湿敏元件的湿敏特性对比,Li Cl/POF元件阻抗变化减小1个量级,元件的响应和恢复时间变长,分析其原因是由于POF内部孔道的孔径(0.6nm)过小,不利于水分子的传输与吸附,因此微孔聚合物作湿度敏感材料有一定的局限性。(3)通过改变反应物单体的浓度制备不同直径的等级多孔聚合物HPPMs微球,选用比表面积最大的HPPMs-1用于湿敏特性的研究,通过物理共混的方法将Li Cl装载到HPPMs-1的孔道中制备湿敏特性优异的Li Cl/HPPMs-1复合湿敏材料。与之前研究的Li Cl/P3HBA和Li Cl/POF湿敏元件对比,Li Cl/HPPMs-1湿敏元件的阻抗变化的量级最大,而且比Li Cl/POF湿敏元件有更短的响应恢复时间。这是由于HPPMs-1中的介孔孔道有利于水分子在材料内部进行传输,微孔孔道促进了水分子的吸附,因此等级多孔聚合物在湿度传感领域具有很大的应用潜力。(4)采用化学修饰的方法在多孔交联骨架上引入Li+合成Li P3HBA和PLBTO。第一种方法是先合成含有可修饰官能团羟基和羧基的多孔聚合物P3HBA,然后再将羟基和羧基转化为含Li+的官能团便得到了Li P3HBA;另一种方法是先将单体间苯三酚中的羟基转化为含Li+官能团,然后再利用含Li+的单体进行聚合反应得到PLBTO。Li P3HBA和PLBTO湿敏元件都具有优异的湿度敏感特性,通过化学修饰的方法将Li+均匀的引入到聚合物骨架中,增强了材料的亲水性,同时多孔交联的结构保证了材料的稳定性。本论文提出发展多孔聚合物材料用于湿度传感器,该类材料有很好的结构稳定性,有利于解决目前湿度传感器面临的高湿稳定性差的问题。拓展了多孔聚合物材料的应用领域,开拓多孔聚合物材料设计的新途径,探索出提高高分子湿度传感器高湿耐水性的新方法。
[Abstract]:Humidity is a common physical quantity in natural environment. Humidity sensor is a device that can convert ambient humidity into a corresponding measurable electrical signal. The basic principle of humidity sensor is to change the electrical conductivity of material based on the interaction between humidity sensitive material and water molecules. Therefore, the sensitive material is the humidity sensor. The key of performance. The amphiphilic polymer of the practical resistance humidity sensor is usually composed of the hydrophobic main chain and the hydrophilic branch with the polar group. The water molecules are adsorbed by the polar group, and the free moving conductive particles are produced by ionization. When the ambient humidity changes, the amount of adsorbed water molecules occurs correspondingly. Changes in the concentration of conductive particles can lead to a change in the concentration of the conductive particles. By measuring the conductivity of the sensitive film, the monitoring of ambient humidity can be achieved. When the amphiphilic polymer material is working under high relative humidity (80%RH) for a long time, the hydrophilic group is easily aggregated because of the strong interaction between the hydrophilic group and the water molecule. In this paper, a new porous polymer wet sensitive material has been developed in this paper to improve the humidity stability of the humidity sensor. In this paper, a new porous polymer wet sensitive material is developed, which is constructed by two different kinds of methods: physical and chemical blending and chemical modification. A variety of porous polymer composite humidity sensitive materials and amphiphilic porous polymer humidity sensitive materials have been obtained, and a series of humidity sensors with excellent properties are obtained. The main contents are as follows: (1) the macroporous polymer P3HBA is prepared by the Fourier alkylation reaction, and the wet sensitive active substance Li Cl is loaded into the pore of the pore by physical blending. Li Cl/P3HBA composite sensitive material with excellent humidity sensitive properties was obtained. By comparing the difference of humidity sensitive characteristics before and after the introduction of the wet sensitive active substance Li Cl, the role of Li Cl in the humidity sensitive mechanism was studied in depth. Two aspects were summed up as follows: first, the introduction of Li Cl enhanced the hydrophilic ability of the composite material and made it suck in the low humidity environment. A certain amount of water molecules can cause the change of the impedance of the humidity sensor. Secondly, in the high humidity environment, Li Cl can ionize ions in the adsorbed liquid layer to participate in the electrical conduction, and further reduce the impedance of the humidity sensor. (2) the microporous polymer POF is synthesized by the solvent heat method, and the wet sensitive active substance Li Cl is installed by the physical blending method. The Li Cl/POF composite wet sensitive material with good humidity sensitivity was prepared in the POF pass. By comparing with the humidity sensitive characteristic of Li Cl/P3HBA humidity sensor, the impedance variation of Li Cl/POF element was reduced by 1 orders of magnitude, and the response and recovery time of the component was longer. The reason for the analysis was that the aperture of the inner pore (0.6Nm) of the internal POF was too small and was not conducive to the transmission of water molecules. The microporous polymer has certain limitations as the humidity sensitive material. (3) the preparation of the porous polymer HPPMs microspheres with different diameters is prepared by changing the concentration of the reactant monomer, and the HPPMs-1 is used to study the humidity sensitive properties of the largest specific surface area, and the Li Cl is loaded into the HPPMs-1 channel by physical blending. Li Cl/HPPMs-1 composite humidity sensitive material with excellent hypensitivity. Compared with previously studied Li Cl/P3HBA and Li Cl/POF humidity sensors, the Li Cl/HPPMs-1 humidity sensor has the largest impedance variation, and has a shorter response recovery time than the Li Cl/POF humidity sensor. This is because the mesoporous channel in HPPMs-1 is beneficial to the water molecules in the material. The microporous channel promotes the adsorption of water molecules. Therefore, the hierarchical porous polymers have great potential in the field of humidity sensing. (4) the first method of introducing Li+ to synthesize Li P3HBA and PLBTO. on the porous crosslinked skeleton by chemical modification is to combine the porous polymer hydroxyl and carboxyl group with polypore polymerization first. Li P3HBA is obtained by converting the hydroxyl and carboxyl groups into Li+ - containing functional groups, and the other method is to convert the hydroxyl groups in the monomers between the monomers to the Li+ functional group, and then the PLBTO.Li P3HBA and PLBTO humidity sensors have excellent humidity sensitivity by the polymerization of the monomer containing Li+. The chemical modification method introduced the Li+ into the polymer skeleton and enhanced the hydrophilicity of the material. At the same time, the porous crosslinking structure ensured the stability of the material. This paper proposed the development of porous polymer materials for humidity sensors. This kind of material has good structural stability and is helpful to solve the high humidity sensor at present. The problem of poor humidity stability has expanded the application field of porous polymer materials, opened up a new way to design porous polymer materials, and explored a new method to improve the humidity and water resistance of high polymer humidity sensor.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2016
【分类号】：TP212

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