Determination of glass transition temperature and application for fabrication of polyphosphazene with high performance

Abstract To determine the relations of performance and structure accurately, polyphosphazenes with various substitution rates of phenoxy and ethoxy were prepared by nucleophillic substitution reaction, their structures and glass transition temperature (Tg) were characterized by NMR and DSC, respectively, and theoretical Tg of polyphosphazenes containing various structural units were calculated by Fox equation. We can find that Tg of polyphosphazenes decreased with increase of ethoxy contents, which improved low temperature resistance of the polymer. According to the measured value and calculated value of Tg, as well as the deduced mathematical expression of Tailor-Gorden equation, the relationships between Tg and ethoxy contents were proposed, which demonstrated that a plot of the Tg vs. ethoxy contents yielded straight lines when polymer chain owned higher substitution rates of phenoxy or ethoxy, while Tg of polymers with more structural units of phenoxy and ethoxy would be adjusted by a parameter of ωB. Based on the proposed relation, the application of fabrication on polyaryloxyphosphazene elastomer with better mechanical properties and low temperature resistance was successfully carried out. Therefore, the proposed methods can be useful in the prediction of polymer Tg and can also be used for structure prediction of polymers to match a target Tg value by this means, which are likely to have broad applications in polymer science fields.