Preparation And Performance Of Ultratough Alginate Based Multifunctional Self-Healing Hydrogel

Hydrogel is a kind of soft material with three-dimensional network structure,composed of polymer and water.Due to its high water content,good biocompatibility and other characteristics,hydrogels have promising applications in smart sensors,drug release,wound dressing,tissue engineering and artificial muscle.Among them,self-healing hydrogel,which can self-heal just like human body after damaged,has become a research hotspot.However,most self-healing hydrogels reported in the literature have poor mechanical properties,which greatly limits their applications.Therefore,it is a great challenge to prepare multifunctional self-healing hydrogels with excellent mechanical properties.Alginate is a kind of natural polysaccharide.Due to its stability,solubility,viscosity and safety,alginate has been widely used in food industry and medicine.It has a large number of carboxyl groups and hydroxyl groups on its molecular chain.In view of its unique molecular structure,this paper endowed sodium alginate with aldehyde groups and prepared multifunctional self-healing hydrogels based on oxidized sodium alginate.The main research and results are summarized as follows:（1）Based on the special structure of the molecular chain of sodium alginate,we synthesized oxidized sodium alginate（OSA）.Then,through the multi-metal-carboxylate coordination bonds,we prepared physically crosslinked OSA/poly（acrylic acid）hydrogel(OSA/PAA-Fe³⁺)by one-pot free radical polymerization.SEM images showed that OSA/PAA-Fe³⁺hydrogels have a porous network structure.FT-IR spectrum showed that Fe³⁺coordination formed.Tensile tests showed that OSA/PAA-Fe³⁺hydrogels have excellent mechanical properties.Its tensile strength and fracture strain can reach 0.1 MPa and 1500%,respectively.The self-healing experiment showed that the hydrogels have fast self-healing ability.Its self-healing efficiency can reach about 90% within 6 hours at 25℃.The conductivity tests showed that hydrogels have good conductivity and strain sensitiveness.（2）Oxidized sodium alginate grafted with dopamine（OSA-DA）was synthesized as a template to conjugate with acrylamide monomer through Schiff base reaction.Then,free acrylamide monomer was in situ polymerized around the OSA-AM conjugate to from OSA-DA/poly（acrylamide）hydrogel（OSA-DA/PAM）.SEM showed that hydrogels have a lot of interwoven microfiber in its network.Tensile test showed that OSA-DA/PAM hydrogel has excellent mechanical properties.Its tensile strength and fracture strain can reach 0.109 MPa and 2550%,respectively.The self-healing experiment showed that the hydrogels have fast self-healing ability.Its self-healing efficiency can reach more than 80%within 6 hours at 25℃.Tensile-adhere test showed OSA-DA/PAM hydrogels have high adhesive strength to various materials.The cytotoxicity experiment showed the hydrogels have good cell affinity.Animal experiments showed that OSA-DA/PAM hydrogel can be used as wound dressing to promote tissue regeneration and wound healing.