Temperature Regulating Evaporation‐Induced Self‐Assembly of Chiral Nematic Cellulose Nanocrystals for Rational Design of Iridescent Films

Abstract

Cellulose nanocrystals (CNCs) are one of the promising bio‐based nanomaterials with a distinctive chiral nematic structure for fabricating optically iridescent films, yet their long evaporation time for self‐assembly and poor flexibility greatly inhibit practical applications. Herein, pure CNCs and modified CNCs films by various molecules (PEG, glucose, and glycerol) were prepared via evaporation‐induced self‐assembly (EISA) under the regulation of environmental temperature, in order to investigate the synergistic effects of modifiers and temperature gradients on CNCs' self‐assembly and film properties. A series of characterizations revealed that cooperation of PEG may improve CNCs dispersion, while glucose induced excessive hydrogen‐bonded agglomeration. The CNCs/PEG/glucose composite (CGP) films prepared via evaporation at 55°C exhibited optimal applicable performance, with enhanced thermal stability, tensile strength and toughness as compared with pure CNCs and single‐modified films. These results suggest that the dual‐modification system by the ternary molecules achieved a synergistic balance of interparticle interactions, effectively suppressing high‐temperature agglomeration, accelerating self‐assembly and maintaining chiral nematic order. This temperature‐modification synergy strategy provides a feasible approach for the efficient preparation of high‐performance CNCs iridescent films, promoting their applications in flexible, optical, and smart functional materials.