Fabrication of porous polyimide hollow microspheres through O/W/O multiple emulsion

Abstract Herein, we demonstrate a novel strategy for the fabrication of porous polyimide hollow microspheres through building oil-in-water-in-oil (O/W/O) multiple emulsion using poly(amic acid) salt (PAAS) water solution as W phase, liquid paraffin (Lp) as O phase, and Op-10, Span-80 as emulsifiers, respectively. After the addition of the chemical imidization reagent, hollow polyimide microspheres with a porous structure were successfully prepared. The morphology and forming process of obtained hollow PI microspheres were well characterized by OM, SEM, FTIR. The results show that size and morphology control of the polyimide hollow spheres was examined by tuning different contents of PAAS, Op-10 and Span-80. Less adhesion and collapse spheres were achieved with PAAS increased up to 3.5wt%. The number of holes on surface of the spheres increases with the decreasing of op-10 content, while the size of the spheres decreases as the span-80 content increases. A phenomenological elucidation of the mechanism for growth of the hollow polyimide architectures has been proposed. This simple method could fabricate different PI hollow spheres, and also used for fabricating the corresponding carbon hollow spheres. Because of the excellent properties of PIs, their porous hollow structure microspheres may be used for coatings, inks, catalyst loading, nanoparticle dispersion, and so forth.