Self-healable and mechanically strong hydrogel using modified nano-cellulose cross linker

Abstract

Hydrogels with mechanical strength and self-healing properties can mimic characteristics of biological load-bearing soft tissues. Thus, they have drawn attention over the past few years.However,itis quite challenging to incorporate both properties simultaneously into the hydrogels. Developing strategies to fabricate mechanically robust and self-healable hydrogels is yet to be realized.In this work, we developed a one-pot method to prepare nontoxic, environmentally friendly hydrogel via free radical polymerization using a modified nano-cellulose cross-linker, natural polymer Alginic acid and FeCl3.6H2O. Here, nano-cellulose cross-linker was derived from micro-crystalline cellulose and then chemically functionalized with a traditional silane coupling agent to introduce a large number of carboxyl groups on the backbone chain of the polymer network. By using Ferric ions, we tried to introduce reversible and dynamic metal coordination bond, which has been proved to improve mechanical and self-healing properties of hydrogels. Dual metal coordination bonds with dynamic features will serve as sacrificial bonds leading to the effective self-healing efficiency after damage. The mechanical toughness of prepared hydrogel was analyzed by universal testing machine and the spectroscopic analysis and rheological measurements corroborated the existence of hydrogen and dual coordination bonds. Finally, the fabricated hydrogels showed excellent self-healing property, which was highly stretchable after damaging without applying external stimulation such as pH or temperature. It is expected that the synthesized hydrogel with high mechanical properties and time-dependent self-healing ability may diversify its practical applications in biomedical fields.