High-strength hemicellulose-based conductive composite hydrogels reinforced by Hofmeister effect

Hemicellulose is a renewable and environmentally friendly biomass polysaccharide. However, because of the low polymerization degree, conventional hemicellulose-based hydrogels often have poor mechanical properties, severely restricting their potential applications. This study involved preparation of a novel high-strength conductive hemicellulose-based composite hydrogel, modulated by a Na2SO4 solution. The hydrogel matrix with a physicochemical double cross-linking structure was created by adding polyvinyl alcohol to the chemically crosslinked networks of gelatin and dialdehyde xylan (DAX) to improve the enhancing effect. After being soaked in a 1 M Na2SO4 solution for 24 h, the composite hydrogel’s network structure was thicker, as revealed by scanning electron microscopy. Its tensile breaking strength (3.02 MPa) and elongation (330.95%) were much higher than those prior to the treatment. Energy dispersive spectroscopy and X-ray diffraction confirmed that the composite hydrogel had a considerable amount of Na+ and SO42- uniformly dispersed throughout. Additionally, the ionic conductivity of the composite hydrogel was measured at 5.4 × 10-3 S/m, indicating a potential use in the field of super-capacitors.