Dissertation > Excellent graduate degree dissertation topics show

Gas sensing properties of hydroxyl modified conductive polymer organic phosphine poison gas sensitive material

Author: XiaLeYang
Tutor: DuXiaoSong
School: University of Electronic Science and Technology
Course: Optical Engineering
Keywords: Gas sensors Conductive polymer Hydrogen bond acidity Polyaniline Derivatives Polythiophene derivatives
CLC: TB381
Type: Master's thesis
Year: 2010
Downloads: 61
Quote: 1
Read: Download Dissertation

Abstract

20th century chemical terrorist incident occurs repeatedly, causing great harm to the people, there is an urgent need to develop a sensor capable of rapid field detection of chemical warfare agents, in order to protect the safety of the public. Quality-sensitive chemical sensors because of their small size, easy to carry, sensitivity and high, and in recent years has gradually become a hot research field of chemical warfare agent detection. The sensitive material is used as the core of the sensor, largely determines the performance of the sensor. Compared with the conventional inorganic semiconductor material, a conductive polymer material has a cheap, simple process and low environmental requirements advantages, the most important is that the gas-sensitive material of the conductive polymer can be deposited on various substrates, and can be to select a different structure of macromolecular chains, and to be modified, to thereby obtain the different chemical sensitivity can improve the sensitivity and selectivity of gas response. Although the present has developed a variety of hydrogen bond acidic material used to detect with HB alkaline nerve agents, but these materials are not conductive. Accordingly, the present first proposed hydrogen bond acidic group is introduced to the conductive polymer, focusing on the hydroxyl functional group-modified synthetic method of the conductive polymer, and polymeric material is applied to the sensor, the different polymer material sensitive characteristics and conductive properties, and its main contents include the following aspects: (1) first designed based on the basic idea of ??the hydroxyl functional group-modified conductive polymer, polyaniline derivatives as polymer monomer aniline and o-hydroxyphenyl the The polymer should have a main chain structure of the same with polyaniline, with the hydroxyl functional groups on the benzene ring at the same time. Using the cyclic voltammetry prepared polyaniline film poly o-hydroxy aniline film as well as aniline - o-hydroxy aniline copolymer films. Confirmed by electrochemical methods, so that the aniline and the ortho-hydroxy aniline copolymerized, the resulting copolymer film having good conductive properties; but also found, the current supplied by the electrochemical analysis of the cyclic voltammetry curves not only The amine group of the o-hydroxy aniline monomer is oxidized to undergo polymerization, and also the oxidation of the hydroxyl group in the monomer. The quartz crystal microbalance (Quartz Crystal Microbalance, QCM) as the electrochemical working electrode, the surface of the device directly DMMP gas sensitivity characteristics in the preparation of the above three kinds of polymer films, the room temperature. The results show that, poly-o hydroxyanil sensor DMMP almost no sensitive features, polyaniline and copolymer sensor response DMMP only minimal value. Finally, to test the several polymer conductive properties. (2) The study showed that the hydroxyl functional groups in the monomer is polymerized, it is easy to be oxidized, so make new synthetic idea, i.e. the monomer to introduce a hydroxyl group → hydroxyl protection → monomer polymerization → deprotection, while the design a two-step preparation of hydroxy functional groups the modified conductive polythiophene derivatives - poly 3,4 - dihydroxy thiophene. The polymer EDOT as a monomer, having the same main chain structure of the polythiophene, with hydroxyl functional groups on the thiophene ring. Chemical oxidation method, synthesis of the polymer, and with the structural analysis is carried out in the infrared spectrum. Next, by spin coating prepared QCM sensor coated with the polymer film, to test the sensitivity characteristics of the sensor at room temperature for DMMP. The sensor of DMMP better response, thin-film material thickness and DMMP gas concentration on the sensitivity characteristics of the sensor has a greater impact, the thicker the film, the greater the concentration of the gas, the higher the response value. Also studied the sensitivity characteristics of the sensor repeatability, stability, and on several of interfering gases. The results show that the sensor in the adsorbed DMMP can not be restored to the initial frequency of the sensor exposed to the air for a long time its sensitivity will have decreased to some extent, but the sensor DMMP gas has a good selectivity. Final test coated with the interdigital electrode of the polymeric material film, the results showed that the polymeric material has good electrical conductivity properties, and the adsorbed DMMP gas, their conductive properties will be a certain degree of impact.

Related Dissertations

CLC: > Industrial Technology > General industrial technology > Materials science and engineering > Smart materials
© 2012 www.DissertationTopic.Net Mobile