Effects of Pluronic F127 on phase inversion and membrane formation of PAN hollow fibers for air filtration

Abstract

© 2019 Elsevier B.V. Among various pore formers, Pluronic F127 (F127), an amphiphilic nonionic surfactant, is an attractive additive which has often been used to create surface pores on hollow fibers and improve the permeate flux. Even though F127 has been employed in polymer dopes for membrane fabrication in various applications, most studies mainly focused on the enhancements of membrane properties instead of its influences on the phase inversion process and membrane formation. Therefore, the objectives of this study were to investigate its effects on the phase inversion process of a polyacrylonitrile/dimethyl sulfoxide/H 2 O (PAN/DMSO/H 2 O)system and the formation of PAN hollow fiber membranes. It was found that the addition of F127 reduced the dope stability and facilitated the solvent-nonsolvent demixing, resulting in a faster phase inversion process. In addition, F127 formed micelles in polymer dopes and induced large pores at membrane surface. Moreover, F127 enhanced the N 2 permeance and mechanical properties of the resultant hollow fibers. Finally, the PAN/F127 hollow fibers were tested for air filtration and showed excellent filtration performance of >99.999% against NaCl aerosols with a geometric mean size of 43 nm. The hollow fiber spun from the PAN/DMSO dope containing 3 wt% F127 possesses the most balanced filtration performance in terms of filtration efficiency, mechanical properties, and gas permeance. Its filtration performance is also superior to most hollow-fiber air filters in the literature. This study may provide useful insights of using F127 for membrane fabrication for various applications.