Preparation of monodisperse fully aromatic polyimide particles via the polycondensation of diethyl hexafluoroisopropylidenediphthalate with 4,4′-diaminodiphenylether in ethylene glycol

Fully aromatic polyimide particles were obtained in a single step via the polycondensation of diethyl (hexafluoroisopropylidene)diphthalate (6FE) and 4,4′-oxydianiline (ODA) using polyvinylpyrrolidone (PVP) as a steric stabilizer in ethylene glycol. Since the monomers are soluble in ethylene glycol, but the polyimide is insoluble, the polyimide particles grew gradually during the polycondensation process. The particle size and size distribution were controlled by varying the molecular weight and amounts of PVP. The particle size decreased with both increasing concentration and increasing molecular weight of the stabilizer. Furthermore, the solvent composition affected the particle size, i.e., the particle size decreased with increasing volume of glycerol as a cosolvent. Monodisperse particles (diameter: 8.5–1.8 μm) were obtained by varying the amounts of PVP and glycerol.