Thermal decomposition of segments with two aromatic rings in thermostable macromolecules

Abstract

Pyrolysis-gas chromatographic-mass spectrometric studies on a series of pseudo-ladder polymers were performed. The pyrolysis at 650° C affects only the aryl ether segments of aryl ether derivatives of the poly[bis(benzimidazobenzisoquinolinones)]. The formation of the volatile thermolysis products are interpreted by the chemistry of the segments decomposed. The pyrolyis of 4,4′-dioxybiphenylene segments results in 4-phenylphenol, analogously to the thermolysis of 1,4-dioxyphenylene which produces phenol. In contrast, 2,7-dihydroxynaphthalene segments decompose producing 2,7-dihydroxynaphthalene and 2-naphthol, analogously to the decomposition of 1,3-dioxyphenylene which releases resorcinol and phenol. Pyrolytic elimination takes place in bis(4-oxyphenyl) ketone or sulphone segments, resulting in carbon monoxide or sulphur dioxide and phenol. Characteristic volatile thermolysis products of bis(4-oxyphenyl)isopropane, bis(4-oxyphenyl)fluorene and bis(4-oxyphenyl) sulphide segments are isopropylphenol, fluorene and phenylfluorene, and hydrogen sulphide, respectively. However, phenol is the main volatile product.