All-cellulose hydrogel with ultrahigh stretchability exceeding 40000%

While cellulose-based stretchable hydrogels have been extensively explored in recent years, all-cellulose hydrogels continue to face the limitation of low stretchability (less than 250 %). Herein, for the first time, we fabricate an all-cellulose hydrogel with ultrahigh stretchability that can exceed 40000 % strain. By ring opening reaction on cellulose anhydroglucose unit rings, secondary hydroxyls are converted to primary hydroxyls, enabling enhanced chain flexibility, and facilitating the formation of abundant hydrogen bonds. As a result, the obtained hydrogel displays remarkable characteristics, including record-high stretchability (44200 %), rapid self-healing property (within seconds), and the unique ability to form cellulose fiber. With simple drawing, a smooth and flexible cellulose fiber can be obtained, demonstrating good processability and a high tensile strength of 226 MPa. Furthermore, the all-cellulose hydrogel can function as a human motion sensor and electrocardiogram electrode for monitoring physiological signals. This simple yet highly effective method will not only propel the advancement of ultrastretchable all-cellulose hydrogels but also create new possibilities for wearable device applications.