| Abstract: | The thermal decomposition of a series of isomeric poly-(oxphthaloyloxyphenylenes) (I–IV) and poly(m-hydroxybenzoic acid) (V) was studied by Direct Pyrolysis–Mass Spectrometry. The results indicate that intramolecular exchange reactions predominate in the primary thermal fragmentation processes, causing the formation of cyclic oligomers which are subsequently cleaved to open-chain fragments. The size and relative abundance of the cycles produced appear to be strongly influenced by steric factors, i.e., by the structure (para or meta) of the repeating unit in each polymer. Remarkably, in the case of poly(m-hydroxybenzoic acid) the formation of cyclic oligomers containing up to seven repeating units is observed. |
