Polyacrylamide/carboxymethyl chitosan double‐network hydrogels with high conductivity and mechanical toughness for flexible sensors

Abstract

Conductive hydrogels are ideal candidate materials for flexible sensors, but the integration of satisfactory mechanical performances with high conductivity to meet the requirements for practical applications remains a challenge. Herein, a tough ionically conductive polyacrylamide (PAAm)/carboxymethyl chitosan (CMCs) double‐network (DN) hydrogel is fabricated via in situ polymerization of acrylamide in CMCs aqueous solution, followed by ferric chloride (FeCl3) solution immersing. The PAAm/CMCs‐Fe3+ DN hydrogel demonstrates satisfactory mechanical properties, including sufficient tensile strength (~440 kPa), prominent stretchability (~715%), high toughness (~1658 kJ m−3), and excellent fatigue resistance, as well as superb conductivity up to 3.1 S m−1. Moreover, the ionically conductive DN hydrogel‐based sensors exhibit high sensitivity in a broad strain window (0%–700%) and can accurately, and repeatedly monitor the motions of body joints, such as finger and wrist, exhibiting great potential in applications of flexible sensors.

Tough, Anti-Swelling Supramolecular Hydrogels Mediated by Surfactant–Polymer Interactions for Underwater Sensors

“…Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) tests of the freeze-dried P­(AA- co -LMA) CTAB hydrogels were carried out according to ref .…”

“…Rheological characterizations were carried out according to ref . A rheological temperature–frequency sweep test was performed from 25 to 90 °C with a shear strain of 0.1% and a frequency sweep of 1 rad·s –1 .…”

Synthesis and Properties of Rosin-Based Composite Acrylamide Hydrogels

“…For tensile tests, the hydrogels were cut into a dumbbell shape using an ASTMD-638 type cutting die, and the tensile data was reported as stress vs. strain curve. For compression tests, the hydrogels were cut into the size with a height of 10 mm and a diameter of 24 mm, and the compression data was reported as compressive stress vs. compressive strain curve [24,25].…”

Stretchable, conductive poly(acrylamide‐co‐maleic acid)/triethylene glycol/NaCl double‐crosslinked organohydrogel with excellent antifreezing and sensing properties

“…Recently, the hydrogel with excellent conductivity and tunable mechanical properties have been widely used to fabricate various sensing elements 13–19 . However, hydrogel contained plenty of water, which can be easily frozen at the temperature below 0°C resulting to the loss of flexibility and sharply decline of conductivity largely limited the applications in low temperature 20–23 .…”

“…12 Recently, the hydrogel with excellent conductivity and tunable mechanical properties have been widely used to fabricate various sensing elements. [13][14][15][16][17][18][19] However, hydrogel contained plenty of water, which can be easily frozen at the temperature below 0 C resulting to the loss of flexibility and sharply decline of conductivity largely limited the applications in low temperature. [20][21][22][23] To solve the aforementioned problem, organic solvents or inorganic salts were introduced to the networks to endow the hydrogel with the extraordinary freezing resistance.…”