Nanomanufacturing of high-performance hollow fiber nanofiltration membranes by coating uniform block polymer films from solution

Abstract

Self-assembled block polymer membranes offer a high density of nanoscale pores with a well-defined size that make them an attractive platform for advanced membrane-based applications, and the development of block polymer membranes in the hollow fiber geometry is crucial in expanding their utility across a broader range of systems. By introducing a facile dip-coating archetype to the self-assembly and non-solvent induced phase separation (SNIPS) nanomanufacturing process, ultra-thin polyisoprene-b-polystyrene-b-poly(N,N-dimethylacrylamide) membranes with highly-ordered, self-assembled nanostructures were coated onto the shell side of a hollow fiber support. By exploiting the chemical flexibility of this fabrication strategy, block polymer membranes demonstrated both a high-throughput and highly selective pores in the nanofiltration regime. Namely, a hollow fiber membrane with a 40 nm-thick active layer and pores with a well-defined diameter of 5.1 nm was fabricated. This high-performance hollow fiber nanofiltration membrane was generated by systematically controlling the nanoscale architecture of the membrane at the interface between the hollow fiber support and block polymer coating. As such, the permeability of this membrane (27 L⁻¹ m⁻² h⁻¹ bar⁻¹) was consistent with that predicted by theory. The readily controlled nanoscale structural characteristics and pore wall chemistries of these membranes make them an appealing platform to be tailored for advanced membrane processes.