Physically cross-linked healable zwitterionic hydrogel for soft robotics

Self-Healing, anti-fouling, and biocompatible hydrogels are highly desirable for soft robotics. The self-healing of chemically cross-linked hydrogels requires external energy or guest molecules to facilitate the reformation of dynamic covalent bonds. It can adversely affect the functionality of micro-robots or impose undesirable limitations on their real-world medical applications. This project aims to introduce a bio-compatible, anti-fouling, physically cross-linked hydrogel that shows inherent self-healing properties by incorporating a zwitterionic component into the hydrogel. Our system is based on random copolymers of sulfobetaine (SB) and acrylic acid (AA). The electrostatic interactions between the positively and negatively charged sections of the SB monomers and the intra- and inter-molecular hydrogen bonds present in the network provide the hydrogel with self-healing properties. We have also employed cellulose nanocrystal (CNC) to enhance the mechanical properties of the hydrogel without compromising its healing efficiency. The system demonstrates a self-healing ability that is independent of the duration the segments are separated before healing.