Microscopic Study on the Molecular Arrangements in the Smectic A, B and C Modifications

The molecular arrangements in three smectic modifications, i.e., the smectic A, B and C states are discussed on the basis of optical observations of smectic spherulites, which were fixed in a very viscous polymer matrix. The observed microscopic patterns for the smectic A state support the conventional idea that the smectic A state has a molecular arrangement such that the long molecular axis lies perpendicular to the layers. In the smectic B state, similar patterns to the smectic A were observed, suggesting a similar molecular arrangement to the smectic A state. On the other hand, the smectic C state exhibits strikingly different patterns from those of the smectic A and B states. Twisted smectic layers are proposed for the molecular arrangement of the smectic C state in order to reasonably explain all the observed microscopic patterns.