Environmentally Friendly Supramolecular Nanosheet Particles for Surface Coating

Global environmental problems have become increasingly severe in the recent years. Although inorganic nanoparticles and nanosheets (NSs) have been developed for their high functionality and stability, their toxicity and nonbiodegradability significantly impact the environment owing to their accumulation within ecosystems. This paper reports the fabrication of environmentally friendly supramolecular NS particles composed of cyclodextrin (CyD), a natural oligosaccharide, and highly biocompatible polyethers, and their stabilization, antifouling, and biodegradation properties. Supramolecules are typically unstable due to their noncovalent bonds; however, end-capped-pseudopolyrotaxane nanosheets (PPRNSs), featuring a bulky group at the axis end, is water-insoluble, maintaining stability even under extreme dilution. The capped-NSs possess polymer brushes, which, when coated on substrates, do not dissolve in water and exhibit repeatable antifouling properties. The crystalline CyDs in the capped-NSs are not water-soluble; however, biochemical oxygen demand (BOD) tests in seawater demonstrate their biodegradability. Thus, PPRNSs have the potential to be novel NS materials that can address environmental challenges. This study is expected to pave the way for advancements in nanosheet materials science and supramolecular chemistry.