A Simple and Effective Physical Ball‐Milling Strategy to Prepare Super‐Tough and Stretchable PVA@MXene@PPy Hydrogel for Flexible Capacitive Electronics

Abstract Biomimetic flexible electronics for E‐skin have received increasing attention, due to their ability to sense various movements. However, the development of smart skin‐mimic material remains a challenge. Here, a simple and effective approach is reported to fabricate super‐tough, stretchable, and self‐healing conductive hydrogel consisting of polyvinyl alcohol (PVA), Ti 3 C 2 T x MXene nanosheets, and polypyrrole (PPy) (PMP hydrogel). The MXene nanosheets and Fe 3+ serve as multifunctional cross‐linkers and effective stress transfer centers, to facilitate a considerable high conductivity, super toughness, and ultra‐high stretchability (elongation up to 4300%) for the PMP hydrogel with. The hydrogels also exhibit rapid self‐healing and repeatable self‐adhesive capacity because of the presence of dynamic borate ester bond. The flexible capacitive strain sensor made by PMP hydrogel shows a relatively broad range of strain sensing (up to 400%), with a self‐healing feature. The sensor can precisely monitor various human physiological signals, including joint movements, facial expressions, and pulse waves. The PMP hydrogel‐based supercapacitor is demonstrated with a high capacitance retention of ≈92.83% and a coulombic efficiency of ≈100%.