The Preparation And Gas Sensor Applications Of Polyaniline-carbon Nanotube Endohedral Composite

Modification with the inner cavity of Carbon Nanotube (CNT) has attractedenormous interest in recent years. From the storage of multi-matericals, people findvarious nano-morphologies and the changes of chemistry or physics property just likethe increasing of stability; promoting of catalytic performance and so on which showthe potential advantages and appilcations of Materials@CNT.In this paper we report on an inter-diffusion polymerization method to encapsulatepolyaniline (PANi) chains inside multiwalled carbon nanotubes (MWCNTs) based onCNT nano-porous membranes. The MWCNT’s inner cavity with a diameter around15nm is designed to be the only path for the diffusion of the aniline monomer and theinitiator, which achieves an efficient and controllable infilling of PANi inside the CNTcavity. The energy filtered transmission electron microscopy (EFTEM) and Ramanspectroscopy confirm the successful encapsulation of PANi chains inside CNTs. Thenew PANi@CNT hybrid exhibits excellent gas sensitivity towards NH3or HCl in awide concentration range and towards C2H4from20ppm to80ppm concentration. Thisnew method (inter-diffusion polymerization) is believed to be much more efficient andtunable in preparing novel endohedral nanotube materials compared to traditionalcapillary infilling approaches.The main topics of our studies are as follows:(1) PANi modify the inner cavity of CNTWe develop a facile inner-diffusion polymerization technique based on the CNTnano-porous membrane to fill conducting PANi inside CNT cavities. The membrane isproducted by microtome cutting from the bulk of CNT array-epoxy resin composite.During the polymerization, the feed side is filled by the solution of aniline and D-camphorsulfonic acid and the permeate side is initially filled by distilled water and2hours later added by the ammonium persulfate and then standing for over24hours.After the polymerization, the diameter of PANi is between10-13nm and over80percent of CNTs have been modified.(2) Sensor applications of PANi@CNT compositeWe place the PANi@CNT composites into the bottles filled by ammonia gas,hydrogen chloride and ethylene with different concentrations and testing the change ofresistance of the composite to prove the application of gas sensor. By the comparing ofthe sensor data of pure CNT and the PANi coated CNT, we can find the PANi@CNTsensor is more sensitive and linear.