High-pressure synthesis and properties of aliphatic-aromatic polyimides via nylon-salt-type monomers derived from aliphatic diamines and benzophenonetetracarboxylic acid

Abstract

Aliphatic polyimides (P-XBTA) having inherent viscosities of 0.4–1.4 dL/g were readily synthesized by the high-pressure polycondensation of the salt monomers, composed of aliphatic diamines having various methylene chain lengths (X = 4–12) and 3,3′,4,4′-benzophenonetetracarboxylic acid (BTA), under 200–250 MPa at 200–320°C. The salt monomers with odd-numbered methylene units were found to be more susceptible to crosslinking than those containing even-numbered methylene chains. The polyimides having even-numbered methylene units were highly crystalline, whereas those with odd-numbered methylene chains were crosslinked and therefore amorphous with only one exception, i.e., P-11BTA. The thermal behavior of these polymers was also studied. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 39–47, 1998