Preparation Of Gas Sensitive Fabrics Through In-situ Polymerization Of Aniline And Its Gas Sensing Property

In this work, four kinds of gas sensitive fabrics Tra, NHP-2-2-1,7, NHPH-2-2-1-2,7 and PNH-1-2-2/7 were prepared by in-situ polymerization of aniline on the polypropylene non-woven fabrics with ammonium persulfate (APS) as the oxidant initiator. For Tra, a piece of non-woven fabrics was immersed in a solution of 0.2 mol/L aniline and 0.2 mol/L H2SO4, then 0.1 mol/L APS was droped into the solution to initiate aniline polymerization on the fabrics to get gas sensitive fabrics. For NHP-2-2-1/7, a piece of non-woven fabrics was soaked in the solution of 0.2 mol/L aniline and 0.2 mol/L H2SO4, then aniline polymerization was initiated in a 0.1 mol/L APS solution on the fabrics when it was moved from the aniline and H2SO4 solution to the APS solution. NHP-2-2-1/7 was obtained by repeated the above steps for seven times. NHPH-2-2-1-2/7 was obtained through the polymerization for seven times in a solution of 0.1 mol/L APS and 0.2 mol/L H2SO4 on the fabrics after it was soaked in the solution of 0.2 mol/L aniline and 0.2 mol/L H2SO4 to absorb the solutes. The polymerization for seven times in the solution of 0.2 mol/L aniline and 0.2 mol/L H2SO4 on the fabrics after it was soked in 0.1 mol/L APS solution to absorb APS led to PNH-1-2-2/7. The polyaniline (PANI) on gas sensitive fabrics was characterized by Fourier transform infrared (FT-IR), the morphologies of the fabrics were observed using scanning electron microscopy (SEM). Gas sensing properties of the obtained fabrics was investigated through monitoring their resistance responses to ethanol. It was found that PANI exits as uniformly distributed nanoparticles on NHP-2-2-1/7 so it displayed good response to ethanol.The effects of the concentrations of aniline, H2SO4 and APS, as well as the polymerization times on gas sensing properties of NHP were vestigated. The results showed that the NHP with good sensing properties, NHP-2-2-1/7, can be afforded through seven time polymrization by using 0.2 mol/L aniline,0.2 mol/L H2SO4 and 0.1 mol/L APS as reactants. Gas sensing properties of NHP-2-2-1/7 was further studied by monitoring its resistance responses to common volatile organic compounds (VOCs), HCl and ammonia. NHP-2-2-1/7 responsed quickly on exposure to acetone, chloromethane, ethyl acetate, ethanol, toluene, HCl and ammonia. The response resistance is linear to the concentration of the VOCs, HCl and ammonia in some specific range. NHP-2-2-1/7 showed much higer sensitivity to ammonia than the VOCs and HCl with a detection limit of 0.58 ppb, because of the strong de-protonation of PANI by ammonia.