Functional polythiiranes - 8. Influence of the terminal group on the thermotropic behaviour of side chain liquid crystalline polythiiranes and identification of a crystalline phase

摘要

Three new side chain liquid crystalline polythiiranes were prepared with new substituants on the mesogenic groups. Their thermotropic liquid crystalline behaviour was studied by the usual techniques (DSC, X-ray diffraction and polarized optical microscopy). Unlike the polyoxiranes described in the literature, the size of the terminal group has no influence on the nature of the mesophases of polythiiranes; only slight changes of the transition temperatures were observed. In this series of polymers, a phase, denoted X, appeared at temperatures below the smectic E phase, and could not be identified by usual characterization techniques. An isothermal kinetic study for the smectic E / X phase transition resulted in an Avrami exponent close to 1, suggesting a one-dimensional ordering occurred during the transformation from the smectic phase. This result, combined with other observations, helped us to assign the X phase to the crystalline phase. [References: 11]