| Surface acoustic wave (SAW) sensor is a new kind of sensor to detect chemical poison gas and explosives. This sensor attracted considerable attention because of its many advantages. The technology employs polymer coating on SAW sensor to collect and concentrate analyte(s) of interest. When the selective coating contacts analyte, the density and elasticity of film will be changed, so the spreading of Rayleigh wave on piezocrystal will be changed with the variety of sediment mass. The analyte(s) and its concertration can be detected by the change of oscillation frequency.The synthesis approachs of coating material, poly (methyl (3, 5-bis (hexafluoro- isopropanol) phenyl) siloxane) (SXPHFA), are studied in the paper. Poly (methylphenylsiloxane) (PMPS) with different molecular weights is synthesized by anionic ring-opening polymerization, characterized by infrared spectrum and GPC. The SXPHFA was synthesized from PMPS and hexafluoroaceton (HFA) and characterized by infrared spectrum, ion chromatograph and hydroxyl analysis. The polymer was coated on the piezocrystal by two methods of solvent evaporation and spin coating. In the gas supply system, dimethyl methyl phosphonate (DMMP) was used as simulation gas, and the responses of SAW sensor were tested at DMMP concertration of 500mg/m3.PMPS with narrow molecular mass distribution of molecular weight between 3500 and 35000 was obtained by adding different amounts of initiator. In the synthesis of SXPHFA, the influences of reaction time, solvent, reaction temperature and catalyzer are investigated. By the result of Characterization, best process conditions were selected. The best condition for the reaction time is 10 hours, the solvent is CS2, and the best reaction temperature is 0℃. In the adsorption test, the influences of solution strength and coating methods on response are discussed.
|
PDF Full Text Request