Self-assembly synthesis of hollow, core–shell and solid soluble oligo(3,4-ethylenedioxythiophene)s microspheres in a mixed solvent

Three different kinds of the mixture of oligo(3,4-ethylenedioxythiophene)s (oligo-EDOTs) microstructures—hollow microspheres with a hole on the surface, cell-like microspheres with core–shell structures and matte solid microspheres were successfully synthesized using FeCl3·6H2O as an oxidant in acetone/water mixed solvent. These three microstructures were obtained only through simply adjusting the volume ratio of acetone and water, the molar ratio of monomer and oxidant or the concentration of the monomer 3,4-ethylenedioxythiophene, respectively, and confirmed by SEM and TEM images. Unlike the insolubility of PEDOT, these oligo-EDOTs microspheres could be dissolved in organic solvent, such as THF, DMF and DMSO. The formation of them might be due to the self-assembly that occurred simultaneously with the oxidation of EDOT monomer on the surface of the well-dispersed EDOT droplets which acted as templates and were formed by the induction of mixed solvent.