Nanoarchitectonics of Exfoliated Flexible Nanosheet Based on Laterally Stacked Macrocycles

Abstract

2D nanostructures including monolayers and few layers exhibit unique properties originating from the anisotropic ultrathin nature. Conventional organic 2D nanostructures, such as covalent organic frameworks, are comprised of the planar π-conjugated macromolecules linked and extended parallel to the layers. The present work shows a new type of exfoliated organic 2D material. The macrocycles are stacked perpendicular to the lateral direction of the nanosheets. Self-assembly of a designed macrocyclic diacetylene monomer with a chair conformation forms the laminated structures containing the layers based on the perpendicularly arranged macrocycles. The exfoliable layered structures are obtained by the topochemical polymerization of the diacetylene moieties. The intercalation and subsequent swelling provide the nanosheets based on the laterally stacked macrocycles in aqueous phase. The colloidal nanosheets possess structural flexibility with the molecular motions originating from the ultrathin nature and conformational diversity. The hydrogel cross-linked with the flexible nanosheets exhibits unique stretching and thermoresponsive shrinking properties. The present work implies the potential of the flexible 2D materials based on the macrocycles.