We present an unconventional approach to various magnetic-plasmonic hybrid nanostructures. In this synthesis scheme, the seed-mediated growth of metals occurs between an initial template and permeable polymer shells. By controlling the repining of small Au seeds during the early stage of crystal growth, Au/Fe3O4 Janus nanostructures or uniform Fe3O4@Au core/shell nanostructures can be produced. This templating method represents a universal approach to Janus and core/shell nanostructured materials of different sizes, morphologies and chemical components. Using hybrid nanorods as example, we will elucidate the tuning of their physical properties by applying an external magnetic field, including plasmonic excitation, optical absorption and photothermal conversion. It enables reversible and remote control over the collective orientations and properties of the nanostructures in both colloidal dispersions and polymer matrix. In the last part of this presentation, we demonstrate that the coupled magnetic-plasmonic properties of these novel nanostructures can be used to fabricate soft actuators and smart devices. If the Janus nanorods are fixed with desirable orientations in a bimorph actuator by the nanoscale magnetic assembly, the bending of the actuator can be controlled by switching the laser polarization. A bipedal robot is created by coupling the rod orientation with the alternating actuation of its two legs. This freestanding, multidirectional photothermal robot that can walk along a predesigned pathway by simply modulating laser polarization and on-off switching.

Unconventional synthesis of magnetic-plasmonic hybrid nanostructures for soft actuators

ACS Spring Meeting 2021

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