Role of Metal(α-Thiopicoline Anilide) as Sensitizer in the Photo-oxidative Degradation of Polyisobutylene

Abstract

The effect of metal tris-(α-thiopicoline anilide)manganese(III) (TPAM) and tris-(α-thiopicoline anilide)cobalt(III) (TPAC) with (0.01 % wt.) on the photo degradation of polyisobutylene (PIB) film was examined by changes in weight average molecular weight, energy of activation and quantum yield of the photolysis of polymer film with 254 nm light. The photo degradation was affected by the kind of metal and by the temperature. The degree of degradation increases with passage of time confirming the random nature of the chain scission of the polymer. The unsaturation produced is proportional to the time of irradiation. Ultraviolet and infrared absorption spectra have been employed to substantiate a mechanism of the degradation process which does not involve hydrogen abstraction from the polymer, but direct cleavage of the polymer backbone and addition of initiating radicals of tris-(α-thiopicoline anilide)cobalt(III) and tris-(α-thiopicoline anilide)manganese(III) at the sites of scission tris-(α-thiopicoline anilide)manganese(III) was found as a photo sensitizer whereas tris-(α-thiopicoline anilide)cobalt(III) merely enhanced the degradation.