Synthesis of an un-modified gum arabic and acrylic acid based physically cross-linked hydrogels with high mechanical, self-sustainable and self-healable performance.

A novel and simple strategy was designed for the synthesis of an unmodified gum arabic (GA) and acrylic acid (AA) based polymer hydrogels using Fe3+ as a physical cross-linking agent. The hydrogels showed a high mechanical strength, self-sustainability and self-healing ability, which depends on the content of GA and Fe3+ in the composition. The fracture stress increased from 0.23 to 0.841 MPa and a decrease in self-healing from 53 to 34% was observed by increasing the GA amount from 12 to 50% respectively. The self-healing performance of the hydrogels enhanced with the existence of the Fe3+ amount on the interface. Therefore, the 3% addition of Fe3+, increased the self-healing ability of up to 70%. Furthermore, the hydrogels also showed an excellent fatigue resistance up to 20 cycles without any rapture and can beard a load of 2.5 kg for a very long time. After 4 min of resting time, the percent recovery in dissipated energy reaching a high value of 95%, indicating the excellent fatigue resistance performance of the hydrogels. The hydrogels contain 3-5% of water at normal conditions and confirm its environmental stability. This work provides a new direction for the synthesis of unmodified GA based physically cross-linked polymer hydrogels systems and can be applied in bioengineering and robotic science in the future.