Preparation of high-performance polymer spheres by using phase-separation during solution polymerization

Aromatic polymers have been recognized as high-performance materials owing to their outstanding properties derived from rigid-rod stricture. Small-sized spherical materials of highperformance polymers have been recently attracted for the industrial usages. However, excellent thermal stability and chemical resistance conversely bring about infusibility and insolubility, and therefore it is usually difficult to process them by conventional methods. In this study, the microspheres of rigid-rod intractable polymers such as aromatic polyimides, aromatic polyesters and aromatic polyamides are successfully prepared as precipitates by means of the reactioninduced phase separation during solution polymerization. Some of them show quite unique morphologies such as microsphere having needle-like crystals on the surface, those having rugged surface and hollow spheres. These morphologies are created by the reaction-induced phase separation including liquid-liquid phase separation and crystallization, and thereby this method is not hampered by the intractability of polymers.