Fabrication of hollow magnetic polyaniline particles via in-situ polymerization in one-pot for UV–Vis-NIR and EMI applications

Abstract

The concern on the adverse impacts of electromagnetic (EM) pollution has continuously increased. Instead of using heavy metal sheet, this work aims to develop magnetic polymeric particles, that can easily be incorporated in coatings, for EM/ultraviolet-visible-near infrared (UV–Vis-NIR) shielding. By carefully design structure and key components, hollow magnetic (HoM) polyaniline (PANI) particles possessing a void encircled with magnetic nanoparticles dispersed in PANI semi-conductive shell were fabricated via the oxidative polymerization in emulsion system. By using ethyl benzene as a soft template and different surfactive dopants, i.e., sodium dodecyl sulfate, sodium dodecylbenzene sulfonate, and poly(sodium 4-styrenesulfonate) (PSS), the HoM-PANI particles (0.5–2 μm) with well-defined hollow structure, high magnetic loading (17–21%wt), and superparamagnetic properties were obtained. The particle size distribution, and magnetic loading were slightly affected by the reaction temperature, whereas molecular weight (Mw) of the localized dopant considerably influenced on the levels of interparticle connectivity, and hence, the conductivity could be tailored. The water dispersible HoM-PANI particles could form opaque coating, and free-standing film. PSS with Mw of 70 K and 1 M yielded the larger HoM-PANI particles and more opaque films than small dopant molecules. Void size was the determining effect on excellent opacity of the coating containing HoM-PANI dispersed in poly(vinyl alcohol) matrix against UV–Vis-NIR, and EM radiation. The ability to tune their optical properties, and electrical conductivity accomplished by designing the particle nanostructure, and doping/de-doping by localized dopants enables them the promising candidates for functional paint, and film for irradiation protection.