A Cellulose Reinforced Polyacrylamide/Polyvinyl Alcohol Dual Network Hydrogel for Flexible Sensors

Abstract In this paper, polyacrylamide (PAM) was used as the main matrix material to form the first layer network structure, and polyvinyl alcohol (PVA) was used as the secondary matrix material to form the second layer network structure. The hydrogels were prepared by free radical in‐situ polymerization and physical cross‐linking. This hydrogel was characterized not only by its semi‐interpenetrating network structure, in which cellulose nanocrystals (CNC) penetrate through the polyacrylamide network but also by the physically and chemically cross‐linked hybrid PAM/PVA double network. The structure and appearance of the hydrogels were characterized by scanning electron microscope and Fourier transform infrared spectrometer, and a series of tests were carried out to detect their mechanical properties, electrical properties and sensing properties. The results show that the hydrogel has good mechanical properties (the elongation at break can reach 600 % and the stress at break can reach 0.16 MPa), and the hydrogel also has good sensing and electrical properties. The addition of organic solvents makes the hydrogels have excellent antifreeze and water retention properties and also have excellent swelling properties. Therefore, the PAM/PVA/CNC dual network interpenetrating composite hydrogel has potential application value in the field of flexible sensors.