The role of butanol isomers on the performance of ammonia sensors based on polypyrrole prepared by microemulsion polymerization

Abstract

The aim of this research is to investigate the effect of butanol isomers used as cosurfactants in the microemulsion polymerization of pyrrole, on the sensitivity of the sensing layers made of polypyrrole (PPy) towards ammonia gas. PPy nanoparticles were synthesized via microemulsion polymerization using sodium dodecyl sulfate (SDS), butanol isomers (n-butanol, 2-butanol and t-butanol) and Ammonium persulfate (APS) as a surfactant and a dopant, cosurfactants, and an oxidant respectively. Design of Experiments (DoE) method was followed in order to explore the effect of isomer type of cosurfactant and surfactant concentration on sensor sensitivity at room temperature towards acetone, ethanol, methanol and ammonia vapors. Under optimal conditions, the sensitivity towards ammonia reached 24.1% at 25 ppm with a response time of 5 s, and a recovery time of 442 s. On the other hand, the sensitivity to all other volatile organic compounds (VOCs) up to 500 ppm was insignificant. Scanning electron microscopy (SEM) micrographs showed that films are formed from nanoparticles with an average diameter ranging from 10 to 20 nm. Absorption spectra in the UV–vis range were all similar. This indicates that butanol isomers have no effect on the optical properties of PPy. Nanostructured SDS doped PPy films prepared by microemulsion polymerization, show good sensing performance towards ammonia at room temperature which make this polymerization method very promising candidate for the fabrication of ammonia sensors.