Morphology and Lamellar Twisting of Spherulites in Cellulose–Ionic Liquid: Effect of Molecular Weight and Temperature

Recently, investigating the morphological regulation and supramolecular architecture of polymer spherulites has become a fundamental issue. Despite cellulose being the most abundant natural polymer on Earth, limited research has focused on spherulite formations. Ionic liquids, as solvents, offer a promising platform for the crystallization of cellulose. In this study, cellulose with different degrees of polymerization (DPs) was crystallized from an ionic liquid solution. The morphology exhibited diverse changes in relation to DPs and crystallization temperature with good regularity. Notably, the presence of left-handed lamellar twists in the negative-banded spherulites and right-handed twists in positive-banded spherulites was observed. The DP-dependent maximum growth rate indicates a transition from extended to folded chain crystallization. These findings contribute to a deeper understanding of the cellulose/ionic liquid interaction and cellulose chain folding, thereby enhancing insights into the supramolecular structure of spherulites.