Liquid crystalline polyoxetanes with two mesogens in the side chain separated by a flexible spacer

The synthesis and thermal behaviour of a new geometry of side chain liquid crystalline polymers consisting on two mesogenic units connected by a flexible spacer as pendent groups of a polyoxetane chain is reported. Changes in the length and parity of the spacer lead to different mesophase properties. This feature is analysed in comparison to similar effects found in dimers and in semiflexible main chain liquid crystalline polymers with analogous chemical structure, where S-C* and S-CA Symmetries have been obtained. Odd-even effects in transition temperatures and enthalpy changes are observed in both monomers and polymers. The symmetry of the mesophases is analysed by means of X-ray diffraction. Evidence for coexistence of different molecular orderings depending on the thermal treatment was found.