A Series of Novel Liquid Crystalline Polymers Showing a Nematic Discotic and/or a Nematic Columnar Phase

Abstract

A series of novel liquid crystalline side chain polyacrylates was prepared, bearing a disk-shaped pentakis(4-methylphenylethynyl)benzene mesogen via an undecanoxy spacer. By using the concept of the polymer analogous reaction, a variety of copolymers with different alkyl acrylate “co-monomers” and increasing mesogen contents were synthesized. The thermal properties of the polymers were investigated by optical polarization microscopy and differential scanning calorimetry. The results indicated that the liquid crystalline characteristics of the polymers are not determined by nature of the co-monomers, but mainly by the weight fraction of rigid mesogen present in the material. All polymers exhibit a nematic columnar phase at lower temperatures. Polymers with a high mesogen content (>61%-wt) exhibit an additional nematic discotic phase at high temperatures, which is unique for polymeric materials.