Slit-Confined Self-Assembly of Cellulose Nanocrystals for Long-Range Ordered Cholesteric Architecture

Long-range ordered cellulose nanocrystal (CNC) architectures are vital for photonic applications, but conventional self-assembly predominantly yields defective, multidomain nanostructures. Herein, this study proposes a slit-confined self-assembly (SCSA) strategy to construct a scalable CNC cholesteric liquid crystal structure with a single orientational domain. Distinct from conventional methods relying on extreme external fields or drying protocols, SCSA utilizes a simple glass slit to steer CNC assembly through synergistic physical effects: gravity drives tactoids sedimentation and interfacial hydrogen bonding enforces preferential alignment. Concurrently, the geometric constraint effectively suppresses the nucleation and propagation of topological defects, enabling the formation of centimeter-scale monodomain cholesteric architectures. As a result, brilliant structural color in aqueous CNC suspensions is achieved without external fields or active stimuli, enabled solely by the synergistic effects of geometric confinement, gravity-driven sedimentation, and interfacial hydrogen-bond anchoring. The resulting highly ordered architecture achieves an exceptional orientation factor of 0.98 and a structural color dissymmetry factor (g) as high as 1.3, accompanied by reversible structural reassembly behavior. Furthermore, upon coassembling with luminescent guests, the system exhibits a giant circularly polarized luminescence (CPL) dissymmetry factor (glum) reaching −1.1. Collectively, this work establishes a robust, straightforward, and scalable route for highly controllable liquid crystal self-assembly, offering promising avenues toward high-performance photonic applications.