Thermal behavior of some aromatic copolyethers containing two different spacers in the main chain

The paper presents a thermogravimetric study combined with mass spectrometry of some aromatic polyethers and copolyethers, in order to obtain information concerning the primary degradation mechanism. The investigated products were synthesised by polycondensation reactions, using a phase transfer catalysis technique. The polymers were synthesized starting from 3,3-bis(chloromethyl)oxetane, bis(2-chloroethyl)-ether or 1,6-dichlorohexane and two bisphenols: 4,4'-dihydroxyazobenzene and 4,4'-dihydroxydiphenyl. Based on mass spectra, a degradation mechanism of polymers containing azobenzenic units was proposed. All the products present a relatively good thermostability, the weight loss beginning up to 260 °C. The presence of the oxetanic moieties induce an augmentation of the thermostability, probably due to the cross-linking reactions that take place as a result of the oxetanic cycles opening. The polymers containing azobenzenic groups have the lower thermostability. If the chain flexibility is augmented, the degradation mechanism is based on chain transfer reactions.