Preparation of konjac glucomannan-borax hydrogels with good self-healing property and pH-responsive behavior

In this study, konjac glucomannan (KGM)-sodium tetraborate (borax) hydrogels with good self-healing property and pH-sensitivity were successfully prepared via a simple one-step method. The effects of KGM and borax contents on the morphology, rheological viscoelasticity, mechanical properties and self-healing performance of the hydrogels were systematically investigated. The results of infrared spectroscopy and scanning electron microscope confirmed the generation of boron-oxygen bonds in the hydrogels. The rheological behavior of the hydrogels further revealed that the cross-linking density of the hydrogel system is positively correlated with borax concentration. Due to this fact, the mechanical properties are enhanced with increasing the borax content. For their self-healing performance, we observed that the recovery rate of the tensile strength is significantly faster than that of the elongation rate at break. Particularly, we found that hydrogel with 6wt% of KGM exhibits the best self-healing performance, i.e., after 5min of self-healing, the mechanical properties can recover by 95%. Besides, the KGM-borax hydrogels also show a good and recyclable pH-responsive behavior.