Side-Chain-Dependent Functional Intercalations in Graphene Oxide Membranes for Selective Water and Ion Transport

Subnanometer interlayer space in graphene oxide (GO)laminatesis desirable for use as permselective membrane nanochannels. Althoughthe facile modification of the local structure of GO enables variousnanochannel functionalizations, precisely controlling nanochannelspace is still a challenge, and the roles of confined nanochannelchemistry in selective water/ion separation have not been clearlydefined. In this study, macrocyclic molecules with consistent basalplane but varying side groups were used to conjunct with GO for modifiednanochannels in laminates. We demonstrated the side-group dependenceof both the angstrom-precision tunability for channel free space andthe energy barrier setting for ion transport, which challenges thepermeability-selectivity trade-off with a slightly decreasedpermeance from 1.1 to 0.9 L m(-2) h(-1) bar(-1) but an increased salt rejection from 85%to 95%. This study provides insights into the functional-group-dependentintercalation modifications of GO laminates for understanding laminatestructural control and nanochannel design.