L. Broadbelt, M. Klein, B. Dean
Oct 1, 1994
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Influential Citations
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Journal
Industrial & Engineering Chemistry Research
Abstract
The model oligomers 2,2-bis[[4-(phenylsulfonyl)phenoxy]phenyl] propane (ISO) and 4,4'-bis[4-(phenylsulfonyl)phenoxy]-1,1'-biphenyl (BP) were reacted neat in argon at 425°C to compare the thermal stability of poly(aryl ether sulfones). Sulfur dioxide was the major gas product, BP generating a slightly higher evolution rate. The weight-average molecular weight increased with reaction time for both oligomers, but after 60 min, the rate of increase was higher for BP. A quantitative molecular level explanation of these observations focuses on the reactive isopropylidene link in ISO. Fission of the weak Ph-SO 2 -Ph bond produces phenyl radicals that abstract hydrogen and add to the oligomer backbone. The latter reaction results in increases in M w and a net weakening of the aryl-SO 2 bond, which leads to increased rates of SO 2 evolution. The value of the relative rate, R rel , of radical addition to H-abstraction was higher for BP than for ISO due to easily abstractable isopropylidene hydrogens