A green strategy to endow superabsorbents with stretchability and self-healability

Abstract

Superabsorbent hydrogels usually offer great free-swelling capacity, but often fail in terms of mechanical properties. Suggested strategies for enhancing the gels toughness usually hamper its water absorbency. Herein, the synthesis of super-swelling hydrogel sheets with superior mechanical properties is reported. The hydrogels have been prepared by the employment of star-shaped lactic acid-based interior crosslinking agents. The hydrophobic interactions, associated to these bio-based sustainable crosslinkers, conferred viscoelasticity and stretchability of up to 1100% to the gels. These transparent sheets were capable of considerable stretching at the swollen state. The employment of these crosslinkers also conferred self-healing characteristic to the modified hydrogels, while acceptable saline-absorbency under load was also preserved. Similar mechanical properties of self-healed films and the pristine films is an evidence of successful healing. The superior properties of the modified superabsorbent polymers (SAPs) are probably attributed to the hydrophobic associations of the crosslinker and a more uniform distribution of stress within the network.