Ion beam induced conversion of PVC into a conducting polyene

Summary form only given. In spite of the extensive development of radiation chemistry involving low energy radiations, the specific effect resulting from the high densities of energy deposited in polymers by heavy particles, such as /spl alpha/ particles or ions, had been recognized for a long time but not exploited till recent years. The formation of a continuous column of ionization along the particle track accounts for the production of new radiochemical products, reported by Gray for Linear Energy Transfers larger than 10 keV//spl mu/m. For such irradiation conditions, efficient recombination processes lead to low free radical production and high molecular fragment losses. The formation of long sequences of conjugated bonds results from this primary modifications. The study of PVC dehydrochlorination induced by a beam of 1 MeV /spl alpha/ particles has been carried out by Rutherford Backscattering Spectrometry and Mass Spectrometry, whereas modifications in the molecular structure have been investigated by visible and infrared spectrophotometry. The distribution of chlorine lossed in the film depth is in accordance with the profile of energy transferred by electronic processes and the kinetics of HCl production is interpreted by a two site mechanism according to the usual radiochemical scheme. The infrared spectrum shows the formation of conjugated double bonds whereas the increase of the conjugation length induces the shift of the absorption edge from the UV towards the visible. Implications for simultaneous formation and doping of conjugated polyenes using ion implantation are discussed.