Self-assembly of robust graphene oxide membranes with chirality for highly stable and selective molecular separation

Abstract

Graphene materials are considered strong materials, and graphene oxide (GO) membranes have great potential for separation; however, state-of-the-art membranes readily disintegrate due to electrostatic repulsion. Herein, we develop a novel cooperative molecular polymerization method to self-assemble robust nanostructured GO nanofiltration membranes by chiral amplification. The tough trade-off problem between permselectivity and stability can be effectively solved when GO nanosheets are highly cross-linked by chiral compounds. Through cooperation effects, chirality can tailor the spacing of GO nanosheets and create numerous chiral sites between GO layers, thus inducing achiral fragments in GO nanosheets to form sophisticated nanostructures. Due to strong interactions between the chiral guest and host nanosheets, the composite membrane exhibited unusual mechanical properties and stability with exceedingly powerful resistance to sonication and water soakage while displaying excellent permselectivity. The prepared rGO/PLDA membrane not only presented very high selectivity towards both negatively and positively charged molecules, but can also be steadily operated in long-term cross-flow filtration. By varying types and contents of chiral polymers, target composite membranes with anticipated nanostructures can be achieved. This strategy provides a facile way to design different lamellar membrane materials for a vast range of practical engineering applications.