Abstract
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 prepared from the same diamine and trimellitic anhydride. Furthermore, two polyimides were prepared from 1,4‐bis‐[4′‐(4″‐aminophenoxy)cumyl]benzene or a mixture of the 1,3‐ and 1,4‐diamines. Moreover, one polyimide was synthesized from PMDA and 1,3‐(4‐aminocumyl)benzene. All polyimides were characterized by elemental analyses, optical microscopy, DSC 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°C, along with a fiber pattern suggest that this LC‐polyimide forms a smectic‐A phase in the melt and a disordered smectic‐B phase in the solid state. Also most other polyimides formed a disordered 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 underline the high potential of polyimides of form layer structures.