Environmental responses of nanostructured polyaniline films based on polystyrene–polyaniline core–shell particles

This paper describes a simple method for fabricating nanostructured polyaniline (PANI) films from polystyrene (PS)–PANI core–shell particles and the environmental responses of the films. Monodisperse PS latex particles synthesized via surfactant-free emulsion polymerization were used as cores, onto whose surface aniline monomers adsorbed with the aid of sodium dodecyl sulfate and were polymerized by adding ammonium peroxydisulfate. The resulting suspensions of core–shell particles were then drop-cast onto substrates and dried. Films composed of fragments of thin PANI shells of tens of nanometers were obtained after the removal of PS by tetrahydrofuran extraction. Another kind of films was prepared by heating the core–shell particles above the glass transition temperature of PS for a short time before the extraction. The morphology was observed using scanning electron microscopy, and the UV–vis spectra were recorded by a spectrometer. Furthermore, we examined the resistance responses of the films to dry gas flow, ethanol vapor, hydrogen chloride, and ammonia. The high sensitivity and fast response should be due to the large surface area interacting with analytes and porosity that facilitates diffusion. In addition, the effect of the packing of PANI shells in the films on the responses was discussed.