EFFECT OF ORGANIC VAPORS ON THE MOLECULAR-CONFORMATION OF NON-DOPED POLYANILINE

A series of studies have been carried out on polyaniline (emeraldine b ase; EB) thin films deposited on glass substrates from aqueous solutio ns of polymerizing aniline (''in-situ'' EB-I film). These films exhibi t a Vis/UV spectrum in which the exciton peak has an absorption maximu m at similar to 600 nm. Exposure of EB-I film to NMP vapor results in a red-shift of the exciton peak to similar to 650 nm (EB-II film). Dop ing of EB-II film by aq. HCl vapor gives a more delocalized electronic structure and higher electrical conductivity than those of the doped EB-I film. It is concluded that EB-I and EB-II exist in ''tight coil'' and ''expanded coil'' conformations respectively which do not change on doping in aqueous HCl.