Synthesis of simple main‐chain type polyimides derived from aliphatic diamines and 4,4″‐terphenyltetracarboxylic acid, and their thermotropic liquid crystalline behavior

Publisher Website
Google Scholar
Abstract
We have synthesized a series of aliphatic‐aromatic polyimides by high pressure polycondensation of monomer salts derived from diaminoalkanes and diethyl 4,4″‐terphenyl‐tetracarboxylates. The polyimides, designated as P‐nTPE, were obtained with n, the number of methylene units in the spacer, ranging from 6 to 12. Among these, the P‐nTPE polyimides with 8⩽n⩽12 from mesophases. The mesophases of P‐8TPE and P‐11TPE are enantiotropic, whereas those of the other polyimides are monotropic. The nematic phase was identified for all polyimides from X‐ray and microscopic observations; only P‐11TPE exhibits polymorphism, in which a nematic phase is followed by a smectic phase upon cooling. The ability for liquid crystal formation in main‐chain polyimides is discussed.