Nanofibrous Chitin Clusters Constructed via Controllable Crystalline Structure Transition for 3D Functional Materials.

Intensively studied polymeric particle production technologies often rely on the combination of polymer self-assembly and particle processing techniques. Herein, an elegant crystallization transition-mediated strategy is proposed to confine molecular self-assembly within a limited range, avoiding the need for extra particle processing steps. This approach enables the production of the regenerated nanofibrous chitin clusters woven with the helical nanofibers. By dissolving the β-chitin in an aqueous NaOH solution and adjusting the degree of deacetylation (DD value) to 28.0-41.4%, the chitin chains self-assembly pathway is facilitated to undergo a crystalline transition from α-chitin to hydrated chitosan. This transition diminishes the chitin chains self-assembly tendency and confines the self-assembly to the submicro- and micrometer scales. The morphological parameters of these chitin clusters, including cluster size, nanofiber tentacle density, diameter, and helical pitch, can be tuned by adjusting the DD value. These nanofibrous chitin clusters are successfully employed as building blocks to create 3D structural materials for thermal insulation and functional food applications, demonstrating their potential in constructing advanced materials. It is anticipated that the crystalline structure transition-mediated concept can be applied to other polymeric particle fabrication, opening up a new avenue for designing advanced particles for various applications.