STRUCTURAL INVESTIGATIONS ON SMECTIC-D AND RELATED MESOPHASES

We have performed time resolved diffraction experiments in order to ob tain a better insight upon the metastable phases surrounding some ther motropic mesophases of cubic Ia3d and Im3m symmetries. These metastabl e phases are columnar hexagonal, smectic or tetragonal, depending on t he nature of the mesogenic molecule. Moreover, it appears that the str ucture of the cubic phase of the 4'-alkyloxybiphenyl-4-carboxylic acid s previously labelled smectic D varies with the lateral group substitu ted on the biphenyl core.