Kinetic Insight into the Formation of Physically Robust Molecular Network in Cellulose Hydrogels

Sol-gel method unlocks the enormous potential of utilizing abundant and renewable cellulose resources. However, the molecular-level structural evolution during the cellulose gelation process is less well understood, bringing challenges for achieving high performance of cellulose hydrogels by regulating their molecular network. Herein, a fascinating journey is unveiled through time-resolved in situ techniques for the evolution of the hierarchical structure of cellulose from micro to molecular scale during the gelation process. The two-regime gelation mechanism of cellulose is proposed. Unexpectedly, it is discovered that the polarity of anti-solvents could effectively control the gelation kinetics and manipulate the molecular network of cellulose hydrogels. As a result, the performance of cellulose hydrogels can be purposefully customized, which are either robust and elastic, or tough and high-damping. Understanding the gelation mechanism of cellulose and its structural evolution kinetics unlocks the pathways to exceptional performance and multifunctionality, which will foster potential advances in sustainable cellulose-based hydrogels.