Chitosan derivative-based self-healable hydrogels with enhanced mechanical properties by high-density dynamic ionic interactions

Chitosan derivative-based self-healable hydrogels with enhanced mechanical properties are reported, which were prepared by polymerization of acrylic acid (AAc) in 2-hydroxypropyltrimethyl ammonium chloride chitosan (HACC) solution. The PAAc/HACC hydrogels exhibit tensile fracture stress as high as 3.31 MPa and a Young's modulus of 2.53 MPa. They can maintain their original shape after 30 repeated compression cycles under various strain conditions, with a compression stress of more than 60 MPa at 99% strain. The damaged PAAc/HACC hydrogels can heal together in the presence of a NaCl salt solution with a self-healing efficiency of up to 61%. In addition, the PAAc/HACC hydrogels have high ionic conductivity and can serve as electrolytes for supercapacitors. The analysis suggests that all these good properties of the PAAc/HACC hydrogels mainly result from their high-density dynamic ionic interactions structure.