Effects of temperature and oxygen on the degradation of doped and undoped polyphenylacetylene

Abstract

The thermal oxidation and pyrolysis of pristine polyphenylacetylene (PPA) and PPA-electron acceptor complexes were studied. Thermogravimetric and differential thermal analyses of pristine PPA reveal that in the presence of substantial amounts of O 2an initial exothermic process first leads to a weight gain followed by a two-step weight loss process. The initial weight gain is attributed to the formation of oxygen-containing groups in the polymer and the presence of these groups has been confirmed by XPS and IR absorption spectroscopy. Halogen and organic electron acceptor dopants interfere with the formation of these groups and promote char formation during pyrolysis. During heating, even when no weight change is discernible, the degree of effective conjugation will decrease which in turn will adversely affect the photoconductive properties of PPA.