Preparation And Characterization Of Rod-like Polymer Film Sensor

During recent years, there were many explore disasters because of gas exploding in coal mine. Thus, it is very important to monitor gas concentrations quickly and accurately in the coal mine. Conducting polymer/inorganic nanocomposites are particularly challenging due to the combined nature of flexibilities and improved process ability of polymers, and attractive modulus, transparency, surface hardness and heat resistance properties of inorganic components.Conjugated conducting polymer nanocomposites, especially organic-inorganic nanocomposites, have drawn the attention of scientists over the last years due to a wide range of potential use of these composites. However, because of theπsystem in the chain carbone backbone, polymer is colloid at room temperature. So it is difficult to be processed and patternmaking. There is no doubt that these properties will block its gas-sensing film to absorb and release gas detected. As a result, the material has different electric, magnetic, sensitive performance compared with normal materials. In order to solve the problem mentioned above, the thesis contained 2 sections as follows:(1) Firstly, PDMEB films, PDMEB/ SnO2 and PDMEB/ In2O3 composite films were prepared on QCM (Surface Acoustic Wave) and SAW (Surface Acoustic Wave) substrate separately using spin coating technique. The films were characterized by optical focus microcopy and FTIR. Spectrum analyses indicated that some kind of interaction did take place between PDMEB and SnO2/In2O3 nanoparticles.The morphology analyses revealed that, a typical stomata structure could be found in the PDMEB/ SnO2 and PDMEB/In2O3 nanocomposite material, and It is evident that there are many pores on the surface of the composite thin film.The result is found that the exist of SnO2 nano-powder and In2O3 have the abilities to make the composite thin film present a vacuum coating porous structure, which is more suitable to the diffusion of gas. By studying their sensitivity to CH4 and CO at the room temperature. PDMEB/ SnO2 and PDMEB/ In2O3 composite thin film gas sensors are more sensitive and their response recovery time is much shoter. According to the study to SAW sensor with different thickness of the film, the thicker the film is, the more serious insertion loss and difficult in starting oscillation.(2) Another composite conductive material Pt-DEB was prepared, which hasπsystem covalent bond in the carbon backbone. Compared with PDMEB, there is a transition metal (Pt) insert into the chain. This difference enhances the conductivity of the material. By studying the sensitivity of Pt-DEB thin film sensor to methane gas CH4, the film sensors was hard to return to initial frequency after the absorption of CH4. And the sensitivity to CH4 with different concentration presented a character of nonlinear. When detecting organic vapor(THF,CHCl3,EtOH and MeOH), Pt-DEB thin film sensor presented excellent response characters and repeatability.