Preparation of polyimide hollow particles using chemical imidization

Abstract Hollow polyimide (PI) particles were successfully prepared using chemical imidization with acetic anhydride and pyridine as the chemical imidization reagents. The imidization reagents were added to the dispersion in which N,N-dimethylformamide (DMF) droplets with dissolved poly(amic acid) (PAmA, the precursor of PI) were dispersed in a cyclohexane medium. In the absence of poly(n-butyl methacrylate) (P[n-BMA]) in PAmA/DMF droplets, approximately 10% of the PI particles had hollow structures. Conversely, in the presence of a small amount of P(n-BMA) in PAmA/DMF droplets (0.2∼1 wt%), all PI particles had hollow structures. The P(n-BMA) would affect the phase separation of the PI in the droplets, thereby promoting the formation of a hollow structure.