Synthesis of Model Compounds of The Nematic Polyester Poly(2,2′-Dimethyl-4,4′-Dioxyazoxy-Benzenedodecanedioyl)

We describe synthesis and phase characterization of model compounds of the thermotropic nematic polymer poly(2,2′-dimethyl-4,4′-dioxyazoxybenzene dodecanedioyl), which consists of regularly alternating rigid mesogenic and flexible aliphatic moieties. Models were composed of the following sequences: flexible-rigid-flexible; rigid-flexible-rigid (9-DDA-9); rigid-flexible; flexible-rigid-flexible-rigid-flexible. Only 9-DDA-9 displays a mesophase (monotropic nematic). The appearance of an enantiotropic nematic phase is associated with the development of a polymeric structure (approximately six repeating units are required).