Single Molecular Layer of Chitin Sub‐Nanometric Nanoribbons: One‐Pot Self‐Exfoliation and Crystalline Assembly into Robust, Sustainable, and Moldable Structural Materials

Abstract Sub‐nanometric materials (SNMs) represent a series of unprecedented size‐/morphology‐related properties applicable in theoretical research and diverse cutting‐edge applications. However, in‐depth investigation and wide utilization of organic SNMs are frequently hindered, owing to the complex synthesis procedures, insufficient colloidal stability, poor processability, and high cost. In this work, a low‐cost, energy‐efficient, convenient, effective, and scalable method is demonstrated for directly exfoliating chitin SNMs from their natural sources through a one‐pot “tandem molecular intercalation” process. The resultant solution‐like sample, which exhibits ribbon‐like feature and contains more than 85% of the single molecular layer (thickness <0.6 nm), is capable of being solution‐processed to different types of materials. Thanks to the sub‐nanometric size and rich surface functional groups, chitin SNMs reveal versatile intriguing properties that rarely observe in their nano‐counterparts (nanofibrils), e.g., crystallization‐like assembly in the colloidal state and alcoplasticity/self‐adhesiveness in the bulk aggregate state. The finding in this work not only opens a new avenue for the high value‐added utilization of chitin, but also provides a new platform for both the theoretical study and practical applications of organic SNMs.