Construction and 3D Printing of Multiscale Silk Fiber‐Cellulose Composite Networks Based on Ionic Liquids

Abstract Microscopic defects in the amorphous regions of natural cellulose affect the mechanical properties of their materials. After dissolution and regeneration, cellulose's mechanical properties are still insufficient for application in advanced materials. Conventional compounding and crosslinking techniques with toxic crosslinking agents are not only cumbersome, but also have limited performance enhancement in cellulose materials Therefore, much attention has been paid to designing and developing more straightforward and efficient cellulose reinforcement technologies. Herein, an in situ multiscalarization strategy is used to form multiscale silk fiber‐cellulose composites (MS‐C) by the gradual nanosizing of silk fibers (SF) under heating in a 1‐butyl‐3‐methylimidazolium chloride solution of cellulose (Cel‐BmimCl). MS‐C are constructed from micro and nano SF, fibroin chains, and cellulose molecules into a multidimensional network. Due to its advantage of multiscale structure, MS‐C has excellent mechanical properties, the tensile strength and Young's modulus, which are 123.06% and 91.68% higher than that of pure regenerated cellulose after 5h heating treatment. Besides, MS‐C has good biocompatibility and can be molded or 3D printed with direct ink writing, showing broad application prospects in medical, bioengineering, and other fields. This multiscale enhancement strategy can also be extended to the research and application of biopolymers such as natural polysaccharides or proteins.