MACROCYCLIC POLYMERS

A new class of thermally stable polymers is described. Condensation of suitable tetramines or tetranitriles with aromatic diamines under the appropriate conditions has afforded polymers that are composed essentially of repeating macrocyclic units. The conditions necessary to obtain a high concentration of macrocyclic units within the polymer have been investigated. Alternative structures and competing reactions have been considered. The polymers obtained by the condensation of pyromellitonitrile (1,2,4,5-tetracyanobenzene, PMTN) with aromatic diamines show a ten per cent loss in weight in air at 500° ±25°C at a constant rate of heating of 4 deg. C/minute. Enhanced stabilities have been observed in inert atmospheres. In particular the polymer prepared from PMTN and 4,4′-diaminodiphenyl ether has been studied in detail. The material can be moulded at 380° ±20°C at 10 000 to 20 000 lb/in2 to give specimens of good tensile strength and high modulus. © 1969.