Preparation and Properties of Highly Stretchable, Adhesive, and Sensitive Ion-Conducting Hydrogels

Abstract

Based on polyvinyl alcohol, polyacrylic acid, and sodium alginate, ion-conducting hydrogels with high stretchability and adhesion were fabricated via a two-step process. Hydrogels were prepared with different contents of cellulose nanocrystals (CNC) and sodium alginate to improve the performance of ion-conducting hydrogels. The samples were tested and analyzed by Fourier transform infrared spectrometer, universal mechanical tester, LCR digital bridge and scanning electron microscope. The results show that the addition of sodium alginate can improve the ductility and mechanical properties of the hydrogel, and with the increase of the amount of sodium alginate, the ductility of the hydrogel shows an upward trend, when the amount of sodium alginate is 0 g, when the CNC is 0, the elongation at break of the hydrogel is 201.4%, and the maximum tensile strength is 0.045 MPa. When the amount of sodium alginate was 1 g and the CNC was 0, the elongation at break of the hydrogel was 769.2%, and the maximum tensile strength reached 0.075 MPa. The addition of CNC will also improve the mechanical properties of the hydrogel, but the addition of excessive CNC will reduce the mechanical properties of the hydrogel. When containing 2 g CNC and 1 g sodium alginate (SA), the elongation at break of the hydrogel was 983.2%, and the maximum tensile strength was 0.098 MPa. When the CNC content increased to 4 g, the elongation at break of the hydrogel decreased to 698.1%, and the maximum tensile strength decreased to 0.065 MPa. When the hydrogel is stretched, the relative resistance of the hydrogel increases with the stretching deformation. And the hydrogel can still guarantee the stability of the change in multiple stretching cycles, which indicates that the hydrogel has potential application value in flexible sensors.