A versatile, highly stretchable, and anti-freezing alginate/polyacrylamide/polyaniline multi-network hydrogel for flexible strain sensors and supercapacitors
Mingjun Yu, Yang Gao, Hengchang Hong, Tao Wang, Zhiping Peng
Abstract
Conductive hydrogels have great potential as electrolyte materials for flexible strain sensors and supercapacitors . However, it remains a challenge to develop multifunctional hydrogels with excellent frost resistance, toughness, ionic conductivity , and electrochemical properties using simple methods. Herein, a “chemical-physical-ionic” cross-linked sodium alginate/polyacrylamide/polyaniline (SA/PAM/Ca 2+ /PANI) multi-network hydrogel was developed by in situ polymerization of aniline monomer within a Ca 2+ -crosslinked SA/PAM hydrogel network. The SA/PAM/Ca 2+ /PANI hydrogel shows excellent mechanical properties, (tensile strength of 0.577 MPa at a strain of 1991 %), high toughness (5.52 KJ·m −3 ), and high ionic conductivity (16.51 S·m −1 at 25 °C and 11.08 S·m −1 at −20 °C). The SA/PAM/Ca 2+ /PANI hydrogel-based strain sensor exhibited high sensitivity (gauge factor of 3.82 at 60–500 % strain), an extensive detection range (0–2000 %), and excellent frost resistance. The strain sensor can accurately monitor various human motions, as well as electrocardiograph (ECG) signals during both rest and exercise. The supercapacitor assembled with the SA/PAM/Ca 2+ /PANI hydrogel electrolyte exhibited a high surface capacitance (177.19 mF·cm −2 at 2 mA·cm −2 ), maximum energy density (21.93 Wh·kg −1 ), and high power density (3089 W·kg −1 ). Moreover, it maintained satisfactory electrochemical stability with 77.8 % capacitance retention after 4000 cycles. Therefore, the versatile SA/PAM/Ca 2+ /PANI hydrogel shows promising potential for applications in flexible wearable electronic devices.