COUNTERION EFFECTS ON THE PORE STRUCTURE OF POLYANILINE - MEMORY EFFECTS

Standard porosimetry was used to study counterion effects in the pore structure of polyaniline (PAn) powder. It was shown that upon swelling in water, the structure of PAn in the salt forms is sensitive to chan ges in the counterion. Emeraldine salts with inorganic anions (Cl-, HS O3- [sic], H2PO4-, BF4-, HCOO-) have a much larger pore volume in wate r than the ''dry'' structures in decane, where a swelling does not occ ur. The PAn salts with organic anions (CF3COO-, CH3C6H4SO3-) are pract ically hydrophobic, sometimes almost like fluoropolymers. It was found that the labile pore structure of emeraldine base ''remembers'' its p rior history, i.e., depends on the salt from which the base was obtain ed.