Toughening Of PAMPS/PAAM Gel And Self-healing Properties

Hydrogels are widely used for their high water absorption,high water retention,environmental sensitivity and biocompatibility.Compared with the single polymer network(SN gel),the double network hydrogel(DN gel)is characterized by two independent asymmetric network structures and the interpenetrating system network,and thus the mechanical strength and toughness of DN gel are significantly improved.Nowdays,compared with biological materials such as cartilage tissue,DN hydrogels still need increase their strength and achieve self-healing properties to expand the further application in the field of biomaterials such as cartilage tissue.This paper is divided into two parts.The first part adopts the ultraviolet curing free radical polymerization method,in which different substances are added into the two-network system of poly2-acrylamide-2-methyl-propanesulfonic acid/polyacrylamide(PAMPS/PAAM)to improve the mechanical properties of hydrogels.The effects of hydrophilic polyvinylpyrrolidone,hydrophobic octadecyl methacrylate and dodecyl methacrylate on the properties of dual network(DN)gels were investigated under optimized conditions.The results indicated that when the content of C18 was 4%(mole percentage of AAM monomer),the compression strength of the gel was 22.03MPa,which was twice that of the common double-network hydrogel,and the fracture compression rate was 98.66%.When the content of C18 was 6%(mole percentage with AAM monomer),the tensile strength of the gel was 1.02MPa,4.08 times higher than that of the common double-network hydrogel,and the elongation at break was 488%,much higher than that of the common double-network hydrogel(198%).The second part uses a micelle copolymerization method to synthesize a hydrogel with self-healing properties.The hydrophobic monomer octadecyl methacrylate and dodecyl methacrylate were embedded in a polyacrylamide backbone to synthesize a self-healing hydrogel under a redox initiation system.The results indicated that the addition of hydrophobic monomers gives the hydrogel a self-healing function.When the C18 content is 6 mol%,the time for complete healing is the shortest.Based on the self-healing stretch before and after healing,the dynamic nature of the network chain attachment region in the C18 hydrogel gives the hydrogel nearly 100%self-healing properties.