Nanocomposite block copolymer membranes with enhanced permeance and robustness by carbon nanotube doping

Abstract

Block copolymers (BCPs) have received extensive attention in the preparation of advanced membranes for precise separations. However, BCP-derived membranes usually suffer from insufficient mechanical robustness, especially for the most extensively studied polystyrene-based ones. Herein, carbon nanotubes (CNTs) are incorporated into polystyrene-block-poly (2-vinyl pyridine) (S2VP) membranes to enhance the mechanical robustness and water permeance. It is found that mild oxidation is enough to enable the homogeneous dispersion of CNTs in the S2VP solution. The CNT/S2VP mixture is directly coated on macroporous substrates, followed by selective swelling-induced pore generation to produce the CNT-doped S2VP nanocomposite membranes. The as-prepared membranes are featured with two sets of pores: swelling-induced pores and incompatibility-induced nanoscale gaps between CNTs and the S2VP matrix, leading to improved permeances without any decrease of the retention performances. Also, owing to the presence of CNTs in the polymer matrix, the membranes show excellent mechanical robustness and exhibit better pressure resistance than neat S2VP membrane without CNT doping. This work demonstrates a simple yet efficient strategy to prepare BCP-based nanocomposite membranes with enhanced permeance and robustness at no expense of retention.