Glass-cobalt Janus shell hollow microspheres: Shell structure dependence of mechanical strength and electromagnetic property

Divisional shell design is a promising strategy to synergize low density, high structural stability, and tunable functionality of hollow microsphere, but detailed study on the role of different shell sections in determining the overall property is lacking. In this work, glass and cobalt are model structural support and electromagnetically functional materials, respectively, of hollow microsphere with a Janus shell structure (glass-cobalt dually layered shell). The glass and cobalt layers serve as the inner and outer sides, respectively, and the effects of their content ratio on the density, mechanical strength, and electromagnetic functionality were studied. It is found that the functional performance depends more largely on the cobalt layer and the glass layer contributes more to the mechanical strength, while a remarkable improvement of the mechanical strength has also been observed with the presence of the functional cobalt layer. Simply by varying the content ratio of the two layers, the electromagnetic property can be tailored in a wide range with the same overall density. When employed as electromagnetic fillers, the Janus shell hollow microspheres exhibit microwave shielding and absorbing performances that can also be reliably adjusted via regulation of the content ratio of the two layers in the Janus shell.