Unentangled Rheological Behavior of a Nematic Azobenzene Polymethacrylate

The rheological behavior of a nematic polymethacrylate containing an azobenzene side group was investigated. The time-temperature superposition principle was found to hold over a large temperature range, as no discontinuities were detected at the isotropic-nematic transition temperature, despite the relatively high molar mass of the polymer. A direct proof of the unentangled behavior of the polymer is provided, which stems from a dynamic model able to predict the relaxation mechanisms by simply knowing the molar mass distribution of the polymer sample.