Preparation and characterization of hybrid double network chitosan/poly(acrylic amide-acrylic acid) high toughness hydrogel through Al3+ crosslinking

Development of bio-based hydrogels with good mechanical properties is of great importance for their excellent biocompatibility and biodegradability. In this paper, chitosan (CS) based double network (DN) hydrogel was prepared by dissolving CS in AlCl3·6H2O aqueous solution instead of acetic acid solution. After dissolving acrylic amide (AM), acrylic acid (AA), N, N'-methylenebisacrylamide and 2-hydroxy-4′-(2-hydoxyethoxy)-2-methylpropiophenone were added into the CS/Al3+ solution and the CS/PAMAA-Al3+ DN hydrogel was prepared by UV polymerization. The hybrid physical and chemical crosslinked network hydrogels were prepared. The tensile and compression properties of CS/PAMAA-Al3+ DN hydrogel were studied. The results showed that the CS/PAMAA-Al3+ DN hydrogels have high toughness, stretch-ability, and excellent shape recovery properties. The CS/PAMAA-Al3+ DN hydrogel could show the tensile strength of 0.54 MPa and elongation at break of 2203.7%. These properties arise from the dynamic ionic interaction between Al3+ and CS/PAMAA macromolecular chains.