Ozone interaction with conjugated polymers - I. Polyacetylene

Free-standing films of cis- and trans-rich polyacetylene (PA) obtained on a Rh(I) catalyst, were treated with ozonized oxygen (O-3 1% by weight on average). The initial superficial charge-transfer complex formed between ozone and the polyene chain and the subsequent ozone accelerated cis-trans isomerization were studied by electronic and FT-IR spectroscopies. A peculiar mechanism of interaction between ozone and polyenic chain was proposed, and cation radicals were observed on the ozone doped surfaces of PA. Ozone treatment of PA films creates a superficial oxidized barrier that prevents subsequent thermo-oxidative destruction of the bulk portion of PA film. This treatment could be a way of protecting PA from degradative oxidation. (C) 1998 Elsevier Science Limited. All rights reserved.