Preparation of aliphatic–aromatic polyimide particles by polycondensation of diethyl hexafluoroisopropylidenediphthalate and diaminooctane in ethylene glycol:

Polycondensation of nylon salt-type monomer composed of diethyl hexafluoroisopropylidenediphthalate and diaminooctane was performed at 130°C in ethylene glycol to form confetti-shaped particles. Before the polycondensation, the salt monomer solution was homogeneous. As the polycondensation proceeded, the solution became turbid and polyimide particles grew to around 7 μm for 8 h. After the polycondensation, small particles precipitated and got deposited onto large particles to form confetti-shaped particles. Rod-shaped particles were also formed by the polycondensation at low monomer concentration in a long reaction time. They were found to be crystalline in form.