The experimental evidence of multi-step delta-relaxation mode in liquid crystalline side chain polymers by time-resolved fluorescence emission spectroscopy

摘要

There has been recognized that there exist three basic relaxation modes in the molecular dynamics of liquid crystalline side chain polymers (SCLCP) - the alpha-, beta- and delta-relaxation process, and the molecular mechanism of the delta-relaxation has been in controversy, i.e. whether it is a "flip-flop" transition or a continuous rotation. The current study provides the experimental evidence of the multiple steps relaxation by time-resolved emission spectroscopy, taking the intrinsic fluorescence from the model mesogen group of 4-cyanobiphenyl. The temperature dependence of the spectra and its dynamics provides new information on the microscopic picture of the delta-relaxation.