title: Reversible redox processes of poly(anilines) in layered semiconductor niobate films under alternate UV-vis light illumination.
abstract: The synthesis of polyaniline (PANI) with semiconducting layered niobate (NbO) to form PANI/NbO hybrid materials and their reversible color change under a unique redox process under the influence of UV and/or visible light have been investigated. The in-situ polymerization of anilinium chlorides (ANI) packed in a regular orientation in a bilayer structure within the NbO interlayers led to PANI/NbO hybrid powders by heat treatment using (NH(4))(2)S(2)O(8) as the catalyst. The resulting PANI of these hybrids showed the characteristics of a fully oxidized quinoid form, i.e., pernigranine (PG). The PANI/NbO suspension in H(2)O was cast on a glass substrate to form a PANI/NbO film after evaporation of the water with a good parallel orientation of the NbO layers against the glass substrate. Upon UV light irradiation in the presence of a reductant such as MeOH, the violet-colored PANI (PG) polymers within the NbO interlayers were reduced by the NbO-induced photocatalytic reactions and led to a colorless PANI, i.e., leucoemeraldine (LE). Moreover, the resulting colorless PANI/NbO films reverted back to a blue-colored PANI, i.e., emeraldine (EM), due to oxidation by the surrounding O(2) gas. The PANI/NbO hybrid films were able to retain repetitive and reversible photoinduced patterning for over 50 cycles under such alternate UV and visible light irradiation.
authors.affiliation: Department of Crystalline Materials Science, Nagoya University, Nagoya, Aichi Prefecture 464-8603, Japan.
authors.forename: Yoshihisa
authors.initials: Y
authors.lastname: Inui
authors.forename: Tatsuto
authors.initials: T
authors.lastname: Yui
authors.forename: Toshio
authors.initials: T
authors.lastname: Itoh
authors.forename: Kimitaka
authors.initials: K
authors.lastname: Higuchi
authors.forename: Takahiro
authors.initials: T
authors.lastname: Seki
authors.forename: Katsuhiko
authors.initials: K
authors.lastname: Takagi