ELECTRICAL, THERMAL, AND PHOTO PROPERTIES OF POLY(PHENYLENE VINYLENE) PRECURSORS .1. LASER-INDUCED ELIMINATION-REACTIONS IN PRECURSOR POLYMER-FILMS

The elimination reaction of polyelectrolyte films of poly(phenylene vinylene) precursor polymers into the fully conjugated chain was induced by irradiation with an Ar+ laser emitting at 514.5 nm. The experiments were conducted using as-cast precursor polyelectrolyte films of both the unsubstituted poly(phenylene vinylene), H-PPV, and its 2,5-dimethoxyphenylene derivative, DMEO-PPV. Precursor polymer films impregnated with an azo-sulfonic dye, which had a strong absorption at the laser emission wavelength, were also irradiated. The elimination reaction was followed by comparing the elemental analysis and the infrared and visible-ultraviolet spectra of the irradiated and nonirradiated areas. With the unsubstituted PPV film no elimination was detected even at power fluence levels up to approximately 350 W/cm-2, but elimination and conversion to the conjugated polymer could be observed at 10 W/cm-2 when the dye was present. For DMEO-PPV the elimination reaction occurred with or without dye impregnation, and similar marking threshold values were measured in both cases. The molecular mechanism used to explain such observations and the possible application in the area of microelectronics are also discussed.