Critical contributions of additives on the fabrication of asymmetric isoporous membranes from block copolymers: A review

Isoporous membranes have attracted increasing attention for their important applications on precise and fast separation. A breakthrough on scalable fabrication of such membranes was made recently by integrating block copolymer self-assembly (S) with non-solvent induced phase inversion (NIPS). This innovative strategy is known as the SNIPS, and is expected to boost the application of isoporous membrane in future. In this paper, we review the additive assisted SNIPS on the fabrication of functionalized, high-performance asymmetric isoporous membranes from block copolymers. An overview of the SNIPS process and its relationship with NIPS is first given, and factors affecting the SNIPS are presented in this part. Then, the SNIPS process using additives to tailor pore formation and surface properties is fully reviewed. This part includes (1) a summary of additives used by the SNIPS, (2) the mechanisms for additives guided polymer assembly and pore formation, and (3) comparison of performances for varied additives used by the SNIPS. This second part is the center of this review. Our summaries focus on the importance of additives on overcoming the challenges faced by the SNIPS strategy. Review of advancement in this field will shed light on the function-led utilization of additives that will enable an easier, flexible and reproducible fabrication of isoporous membranes with advanced performance. Future directions are provided at the end of this paper.