Template-free synthesis and characterization of single-phase voided poly(o-anisidine) and polyaniline colloidal spheres

Single-phase hollow poly(o-anisidine) colloidal spheres with uniform sizes were directly synthesized in dilute aqueous solution of o-anisidine in the presence of a small amount of an initiator, cupric acetate or basic cupric bromide, Cu-2(OH)(3)Br, under hydrothermal conditions. The void volume and size of hollow poly(o-anisidine) colloidal spheres can be readily tuned by varying the hydrothermal reaction time and adjusting the ratios between the starting reactants. The formation of voided poly(o-anisidine) results from a diffusion-related process driven by the relatively large concentration change between polymer core and solution as well as the high pressure and temperature under hydrothermal conditions. At the same time, the mesostructures of poly(o-anisidine) are dependent on reaction time, temperature, and monomer concentration. An extension of this one-pot synthetic method yields hollow polyaniline colloidal spheres.