LC-POLYIMIDES .32. CHARACTERIZATION OF THE MITSUI-TOATSU LC-POLYIMIDEAND RELATED POLYIMIDES

Two polyimides were prepared from 1,3-bis[4'-(4 ''-aminophenoxy)cumyl] benzene and 1,2:4,5-benzenetetracarboxylic dianhydride (PMDA) or 1,8:4 ,5-naphthalenetetracarboxylic dianhydride. A poly(amide-imide) was pre pared from the same diamine and trimellitic anhydride. Furthermore, tw o polyimides were prepared from 1,4-bis-[4'-(4 ''-aminophenoxy)cumyl]b enzene or a mixture of the 1,3- and 1,4-diamines. Moreover, one polyim ide was synthesized from PMDA and 1,3-(4-aminocumyl)benzene. All polyi mides were characterized by elemental analyses, optical microscopy, DS C and various X-ray measurements. Only the polyimide of PMDA and the 1 ,3-amine proved to be thermotropic. SAXS and WAXS measurements between 25 and 350 degrees C, along with a fiber pattern suggest that this LC -polyimide forms a smectic-A phase in the melt and a disordered smecti c-B phase in the solid state. Also most other polyimides formed a diso rdered smectic-B or a smectic-A glass in the solid state. However, the polyimide derived from 1,3-(4-aminocumyl)benzene crystallized in the form of a smectic-H phase with tilted mesogens. All results together u nderline the high potential of polyimides to form layer structures.