Supramolecular Polymer Hydrogels through Rapid Polymerization Enabled by Tannic Acid-Silver Dual Catalysis for Next-Generation Flexible and Wearable Sensors

Abstract

Recently, there has been growing interest in employing conductive hydrogels in advanced flexible strain sensing technology. However, the prolonged polymerization process and functioning decline under harsh conditions have hindered their implementation in practice. Although ammonium persulfate (APS) could be activated at 50 to 60 °C to trigger the polymerization process, this procedure is time-consuming and requires additional energy. The current research developed supramolecular polymer hydrogels (SuPH-Ag-x) by the rapid polymerization of acrylamide-co-lauryl methacrylate (AAm-co-LM) via a tannic acid-silver (TA-Ag)-mediated dual catalysis mechanism. The TA-Ag dual catalysis system rapidly triggered APS to generate free radicals and initiated the polymerization of AAm-co-LM. The inclusion of TA-Ag metal ion nanocenters, which function as active linkage through hydrogen bonds and hydrophobic associations, can effectively fade away energy, yielding SuPH-Ag-2% with high tensile strength (1038 kPa) and extensibility (1358%). The engineered SuPH-Ag-2% has a good electrical conductivity of 0.25 S/m, allowing for strain up to 700%. Likewise, with an applied strain of 1000%, the engineered hydrogels exhibit exceptional sensitivity (gauge factor of 27.9), making them suitable for monitoring a variety of human body gestures (such as wrist, elbow, and knee), small physiological signals (such as finger movements and voice), and pressure sensing. This study is intended to contribute a potential approach for the quick fabrication of conductive hydrogels for implementation in smart automation, healthcare equipment, and versatile electronic epidermis applications.