Production of NiMn2O4 hollow spheres and CoFe ₂O ₄ bowl-like structures by using block copolymer stabilized polystyrene spheres as a hard template

Abstract

The aim of this study is to highlight the use of polystyrene (PS) latexes stabilized with block copolymers as a hard template in the production of metal oxide hollow spheres. PS latexes produced by dispersion polymerization by stabilizing with tertiary amine methacrylate-based diblock copolymer were used as a hard template in the preparation of nickel manganese oxide (NiMn ₂O ₄) hollow spheres and cobalt iron oxide (CoFe ₂O ₄) bowl-like structures. Thanks to the diblock copolymer stabilizer with tertiary amine functional groups on the PS surface, precursor salts of CoFe ₂O ₄ and NiMn ₂O ₄ were first homogeneously deposited on the surface of PS latexes with a controlled precipitation technique. Then, metal oxide hollow spheres and bowl-like structures were produced by calcination. XRD results showed that CoFe ₂O ₄ and NiMn ₂O ₄ structures were successfully obtained after calcination. The thermogravimetric analysis results showed that the CoFe ₂O ₄ and NiMn ₂O ₄ contents of the hybrid PS spheres were in the range of 26.0–28.6 wt%. SEM images showed that the inorganic-polymer spheres fused with each other after calcination to form larger magnetic CoFe ₂O ₄ bowl-like structures. SEM images also indicated successful production of highly rough NiMn ₂O ₄ hollow spheres with nanosheets on the surface.