Synthesis and characterization of a novel liquid crystalline polymer showing a nematic columnar to nematic discotic phase transition

A novel liquid crystalline polyacrylate, exhibiting a nematic columnar and a nematic discotic phase, the latter not found in any polymer previously, h as been synthesized using a polymer analogous reaction, substituting the di scotic mesogens on a reactive polymer. The highly flexible concept of the p olymer analogous reaction enables us to introduce structural variations and to create and control molecular architectures. The mesophases of polymer 1 , bearing the pentakis(methylphenylethynyl)benzene mesogen via a flexible u ndecanoxy spacer, as well as its low molar weight homologue 2, were fully c haracterized by optical polarizing microscopy, differential scanning calori metry and powder X-ray diffraction. The thermal behavior of both compounds is qualitatively similar. Both materials exhibit a nematic discotic phase ( N-D) at higher temperatures, which is unique for the polymer, as this phase has only been observed in low molar mass materials so far. At lower temper atures 2 crystallizes, whereas 1 undergoes a transition into the nematic co lumnar phase (N-col).