Water vapor induced phase separation: a simple and efficient method for fabricating polyetherimide microspheres

In this paper, a simple and efficient method coupled with water vapor induced phase separation (WVIPS) technique has been successfully applied for the fabrication of Polyetherimide (PEI) microsphere, exhibiting well spherical shape with a relatively uniform size. The formation mechanism of water vapor induced phase separation process is discussed in detail. Furthermore, the effects of the PEI solution concentration, preparation temperature and relative humidity (RH) on the structure and size of PEI samples were investigated. Lower PEI solution concentration is much more favorable to fabricate PEI microspheres. The SEM images and the particle size analysis show that adjusting the preparation temperature and relative humidity during the fabrication process can control the average size of PEI microspheres, ranging from 725 nm to 1.9 μm based on the 3 wt% PEI solution system. This WVIPS method is simple and efficient, and could broaden the applications area of PEI composite materials.