Magnetic solvent-free nanofluid based on Fe₃O₄/polyaniline nanoparticles and its adjustable electric conductivity

A magnetic, solvent-free nanofluid with a core-corona-canopy structure based on Fe₃O₄/polyaniline is synthesized for the first time. The solvent-free nanofluid has magnetic properties owing to the Fe₃O₄ core, flow ability because of the flexible chain canopy, and conductivity due to the conductive polyaniline corona and Fe₃O₄ core. The canopy structure possesses a nanofluid fraction of 87.7 wt%, which is high enough for it to act as the continuous phase and thus warrant fluidity. The liquid property is verified by rheological test. The percentage of crystallinity of the solvent-free nanofluid is 43%. The electric conductivity of the solvent-free nanofluid changes with temperature. The conductivity of the aqueous solution of the nanofluid can be adjusted by changing the strength or direction of the magnetic field. The fabricated solvent-free nanofluid has wide potential for application; for example, its CO₂ capture capacity can reach 3.1 mmol g^-1. With magnetic responsiveness, the Fe₃O₄/polyaniline nanofluid aqueous solution can be used in magnetic field detection.