Synthesis of polyaniline particles via inverse and direct miniemulsion

Polyaniline (PANI) latex particles have been synthesized using both inverse and direct miniemulsion polymerization techniques. It is shown that inverse miniemulsions of anilinium hydrochloride can be oxidized by simple H2O2, thus resulting under optimized conditions in highly crystalline PANI particles dispersed in hydrocarbons with high volume fraction. The resulting structure is identified as emeraldine, which however crystallizes in a new crystal morphology. Oxidation of aniline miniemulsions in water with diverse oxidants from the continuous phase also leads to highly crystalline PANI, which however has a low colloidal stability. Additional employment of a costabilizer in this case leads to stable aqueous PANI dispersions with for water-based systems otherwise unreached local structural order.