Thermal behavior and molecular simulation of liquid crystalline polymers containing a pentamethylenic spacer

The paper presents a study concerning the thermal stability and molecular simulation of some aromatic polyethers, containing a pentamethylenic spacer. The polymers were synthesised using a phase transfer catalysis technique, starting from 1,5-dichoropentane and different bisphenols: 4,4′-dihidroxyazobenzene, 4,4′-dihidroxydiphenyl and bisphenol A. For the investigated polymers the molecular simulation was performed prior the synthesis in order to predict the possibility of liquid crystalline behavior. Molecular simulation was also used as a complementary analysis method for a better understanding of the thermal behavior. Thermogravimetric analysis, in static air atmosphere, with a heating rate of 10 °C/min, was used. Cerius2 and Hyperchem programs were used to perform the molecular simulations. All the polymers present a good thermostability with weight loss being up to 300 °C. The kinetic characteristics suggest a complex degradation mechanism, based on successive reactions. The inter-chain interaction estimated using the polar surface and the chain conformation do not significantly influence the polymer thermostabilities. A comparison between simulated and experimental values of the isotropisation temperature and temperature corresponding to 50% weight loss was performed.