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.