Competing Self‐Assembly to Access Helical Chitin Nanofibers for Advanced Chitinous Materials

Abstract Self‐assembly affords a rich design space in fabricating polymeric nanomaterials. However, the crystalline polymer often exhibits the vigorous self‐assembly process due to the extensive inter‐ and intra‐molecular interactions, leading to the challenge in controlling their self‐assembly behavior at the nanoscale. Herein, this work proposes a competing self‐assembly strategy to regulate the molecular self‐assembly tendency of chitin (a semi‐crystalline polysaccharide) for achieving the regenerated chitin nanofibers with helical structure. This approach focuses on subtly modulating the noncovalent interactions among the chitin chains through deacetylation in a homogeneous system. By fine‐tuning the degree of deacetylation (DD) to a moderate level (≈26%–37%), this work facilitates the chitin chains to compete self‐assembling into the α‐chitin and hydrated chitosan crystalline structure, which effectively mitigates the overall self‐assembly tendency of the chitin chains and ultimately restricting their aggregations to nanoscale dimensions. This fabrication concept achieves various chitin nanofibers morphology (single, randomly branched and comb‐like), all featuring a helical configuration. The chitin nanofibers are successfully processed into the nanopaper and bioink, highlighting the potential in constructing high‐performance materials. This work anticipates that the competing self‐assembly concept can be extended to other crystalline polymers with strong molecular interactions, offering a new pathway to design advanced nanomaterials for diverse applications.