FORMATION OF CONJUGATED POLYENE AND POLYYNE STRUCTURE BY KRF EXCIMER LASER-INDUCED DEHYDROCHLORINATION ON POLYVINYLIDENECHLORIDE FILM

The surface dehydrochlorination of poly(vinyldenchloride) film was per formed to produce a conjugated polyyne and polyene structures by photo -irradiation with a KrF excimer laser at 248 nm in a vacuum chamber. T he reaction was confirmed by detection of HCl with a mass spectrometer and by measurement of chlorine content on the film with X-ray photoel ectron spectroscopy. UV-visible absorption spectroscopy for the laser- treated film showed the formation of new broad absorption bands in the visible and near IR region, indicating that sequential dehydrochlorin ation induced the formation of conjugated carbon multiple bonds in the polymer chain. Its conjugation number is estimated to be 30 for a tri ple bond and 10-25 for a double bond from the peak positions on the Ra man spectrum of the film. ESR spectra of laser-irradiated PVDC powder also showed long-lived radicals having a narrow band width (Delta H-pp = 0.15 mT), suggesting that the radicals were delocalized on the conj ugated bonds. (C) 1998 John Wiley & Sons, Inc.