UV-induced electrical and optical changes in PVC blends

2-Chloro-polyaniline (2-CI-PANI) in its non-conducting (emeraldine base, EB ) form, prepared by a chemical route, was dissolved together with poly-(vin ylchloride) (PVC) in THF for casting into thin (10-50 mum) films. Upon expo sure to UV radiation, the electrical conductivity of these films increased by more than 4 orders of magnitude (from 10(-6) to 10(-2) S/cm). This is at tributed to the dehydrochlorination of PVC by exposure to energetic photons and subsequent doping of 2-Cl-PANI (i.e. conversion to emeraldine salt, ES ) by in situ created HCl. The doped films could be returned to their undope d form by exposure to NH3 vapours. The W-induced doping/NH3 undoping cycles could be repeated several times. Various spectroscopic techniques were emp loyed to follow the changes in the films upon exposure to UV radiation. The same photo-dehydrochlorination process has also been utilized for optical and/or lithographic purposes by preparing PVC blends containing methyl viol et, and acid-base indicator dye. The photo-dehydrochlorination can be effec tively sensitized by incorporating hydroquinone into the PVC blends contain ing methyl violet.