Preparation And Gas Sensitivity Of Conductive Polymer Polyaniline And Its Composites

Gas sensors are an important class of chemical sensors,which are widely used in the fields of environment,food,petrochemicals and aerospace.Gas-sensitive materials are the core of gas sensors.Compared with traditional inorganic semiconductor gassensitive materials such as tin dioxide,titanium dioxide,zinc oxide,conductive polymer gas-sensitive materials such as polythiophene,polypyrrole,and polyaniline have the advantages of low cost,easy availability,and simple preparation.The most important point is that conductive polymer gas-sensitive materials can be used at room temperature,therefore,the application range of gas sensors has been broadened.Among them,polyaniline has become one of the most promising conductive polymer gas-sensitive materials due to its unique doping mechanism,good conductivity and great environmental stability.However,due to the huge interaction force between polyaniline molecules,practically insoluble and infusible,poor mechanical properties and processing properties many practical applications have been limited.The composite material of polyaniline and inorganic compound can improve its performance,increase sensitivity,and obtain excellent characteristics that a single material does not have,so that it can be used more widely.In view of the above problems,this article mainly studies the following four parts:(1)The chemical oxidation method was used,with aniline as the monomer and amine persulfate as the chain-forming agent.Polyaniline(PANI)materials with molar ratios of aniline to acid of 1:0.5,1:1 and 1:1.5 were prepared respectively in tartaric acid,salicylic acid and camphorsulfonic acid.And their characteristics and gassensitive properties were studied.The experimental results show that the PANI materials prepared at 25?,60? and 90? in camphor sulfonic acid at a ratio of 1:1 have the best sensitivity to H2 and great response-recovery time.(2)Using chemical oxidation,PANI/MWCNTs composites containing 5%,10%,and 15%of multi-walled carbon nanotubes(MWCNTs)were prepared.MWCNTs/SnO2 binary composites were synthesized by the hydrothermal method,and PANI/MWCNTs/SnO2 ternary composites containing 5%,10%,and 15%of MWCNTs/SnO2 were prepared.Fourier transform infrared spectroscopy(FT-IR)and X-ray diffraction(XRD)analysis were performed to verify that the composites were synthesized in the experiment.(3)The hydrogen-sensitivity characteristics of composites with different contents of MWCNTs and polyaniline were studied in experiments.The hydrogen-sensitivity characteristics of the composites were analyzed at 25?,60?,and 90?.The research results show that at a temperature of 60?,15%PANI/MWCNTs composites have higher sensitivity,shorter response time and good repeatability.(4)The hydrogen-sensitivity characteristics of ternary composites with different contents of MWCNTs/SnO2 and polyaniline were studied at 25?,60? and 90?.The results show that the ternary composites have greatly improved hydrogen sensitivity characteristics than PANI materials.At 60?,10%PANI/MWCNTs/SnO2 composites have higher sensitivity,shorter response-recovery time and good repeatability.