(160e) Inorganic Nanocomposite Polymer Particles with Topological, Optical, and Magnetic Anisotropy

Janus particles possessing different optical, magnetic, and surface chemistry and morphological characteristics are interesting in a number of areas including display, imaging, sensing, catalyst, smart surface, and rheological fluid applications. Current challenges are related to the creation of spatially controlled functionalities as well as the lack of simple, scalable synthesis approaches. In this study, a simple method, electrohydrodynamic (EHD) co-jetting is utilized to generate multifunctional anisotropic spherical particles.

To provide multifunctional anisotropy within one particle, two optically and chemically distinctive inorganic nanocrystals [a white colorant, titanium dioxide (TiO₂, < 100 nm) and a black pigment, magnetite (Fe₃O₄, ~10 nm)] were were processed via electrohydrodynamic co-jetting. The two metal oxides were suspended into separate copolymer solutions containing poly(acrylamide-co-acrylic acid), (p(AAm-co-AA)] and ethylene glycol. The EHD co-jetting process yielded bi-compartmentalized nanocomposite spherical particles (464 ± 242 nm), which were subsequently proccessed by thermal crosslinking for stabilization. Because of the difference in size and optical color between TiO₂ and Fe₃O₄, it is possible to differentiate the surface morphology and appearance of two compartments, such that the surface of titanium dioxide is optically brighter than the magnetite region. The result is a surface morphological Janus particle. Finally, the magnetic anisotropy of the particles is utilized to demonstrate control of the particles' positions using an external magnetic field.