Critical Role of Degree of Polymerization of Cellulose in Super-Strong Nanocellulose Films

Translation of the outstanding mechanical performance of individual nanocellulose to macroscopic nanocellulose films can be achieved by various alignment techniques. However, attention has seldom been paid to the degree of polymerization (DP) of cellulose that plays a pivotal role in increasing the mechanical strength of nanocellulose films. In this work, nanocellulose film with superior tensile strength (1,014.7 +/- 69.1 MPa) is presented by a cellulose DP protection strategy. An alkaline sulfite-anthraquinone-methanol pulping is applied to not only rapidly remove most of lignin and hemicellulose from wood blocks, which facilitates the formation of hydrogen bonds among neighboring fiber cell walls in subsequent mechanical pressing, but also to significantly suppress the decomposition of cellulose DP. Such strong nanocellulose film sheds light on unlocking the exceptional mechanical potential of cellulose and has the potential for use in advanced applications traditionally dominated by nonrenewable materials such as plastics, glass, and metals.