Preparation and Properties of Adhesive Self-Healing Conductive Hydrogel

By using acrylamide (AM), sodium oxyalgae (OSA) and polydopamine-modified polypyrrole (PDA-PPy) as raw materials, a multifunctional hydrogel PAM/OSA/PDA-PPy (PODY) with adhesion, self-healing and conductivity was prepared. The aldehyde group of OSA reacts with the amino group of AM to form imine bond. Because PDA-PPy carries a large number of catechol groups and conductive groups, it endows hydrogels with good adhesion and conductivity. At the same time, more hydrogen bonds are created inside the hydrogel. The structures of OSA, PDA-PPy and PODY hydrogels were analyzed by Fourier transform infrared spectroscopy, hydrogen nuclear magnetic resonance spectroscopy（¹H-NMR） and scanning electron microscopy. Their mechanical properties, adhesion properties, self-healing properties and electrical conductivity were characterized by universal electronic testing machine, rotary rheometer and four-probe tester. Results show that the elongation at break of PODY hydrogel is up to 928%, and the tensile strength is up to 194 kPa. The maximum adhesion strength of the hydrogel on pig skin, glass and plastic is 9.0, 17.6 kPa and 22.8 kPa, respectively, and good adhesion strength is still maintained after three cycles of adhesion. PODY hydrogel can form a stable three-dimensional network and has good self-healing performance. The maximum conductivity of PODY hydrogel is 0.248 S/m. It lays a good foundation for its application in the field of wearable sensing.