Preparation of aliphatic polypyromellitimide particles by polycondensation of nylon-salt-type monomers derived from aliphatic diamines with diethyl pyromellitate in ethylene glycol

Abstract

Polycondensations of nylon-salt-type monomers composed with diethyl pyromellitate and aliphatic diamines with various methylene lengths were performed at 130 °C in ethylene glycol to afford flower-like particles. Before the polycondensation, the salt monomer solution was homogenous. As the polycondensation proceeded, the solution became turbid and polyimide particles grew to around 15 µm in 8 h. Further polycondensation broke the particles into small pieces. The polyimide particles showed the distinctive odd-even effect of the methylene chain of diamine in both inherent viscosity and crystallinity. The polyimide particles using diamine with even-methylene length had higher crystallinity and lower inherent viscosity than those using diamine with odd-methylene length.