The chemical and colloidal stability of polyaniline dispersions

The chemical and colloidal stability of polyaniline dispersions stabilized with poly(N-vinylpyrrolidone) has been tested in acidic, neutral and alkaline aqueous media. The dispersions were exposed to elevated temperature of 105 degrees C for 1000 h, to sonication, repeated freezing-melting cycles, or to irradiation with UV-visible light. The changes in the chemical structure were assessed by UV-visible spectroscopy. The colloidal properties were characterized by determination of the particle size and polydispersity by dynamic light scattering. The stability of colloidal dispersions was good, both in the chemical and colloidal respect. It was not important whether the medium was acidic or alkaline. The colloids can be stored for 10 years without changes in their stability. (c) 2004 Elsevier Ltd. All rights reserved.