Preparation and Adhesion Properties of Bio-Hydrogels with Hydrophilic-Hydrophobic Double Networks

Wet (underwater) adhesive materials have wide applications in biomedical and engineering fields. However, a hydration layer on the substrate surface severely prevents the interface interaction between adhesives and substrates, resulting in sharp reduce or even disappearance of the wet adhesion property. Therefore, it is of great significance to prepare adhesive materials with wet adhesion property by removal of the hydration layer via hydrophobic interaction. In this paper, amino acid based monomers, N-acrylylglycine (ACG) and N-acrylyl-L-phenylalanine (ACP) were synthesized, and then poly(N-acrylylglycine-N-acrylyl-L-phenylalanine) hydrogels (P(ACG_x-ACP_y)) were further prepared via hydrogen cross-linking and chemical cross-linking. The intermolecular interactions and properties of the P(ACG_x-ACP_y) hydrogels were regulated by adjusting the composition ratio of ACG to ACP. Their adhesive properties were then detected by lap-shear and tensile tests, respectively. The results showed that the hydrogels had well adhesive properties. The maximum wet lap-shear adhesive strength to pig skin could reach 80.2 kPa, when the molar ratio of ACG to ACP of hydrogel was 1∶1. Moreover, the highest compression strength of the hydrogels was 2.2 MPa. Cytotoxicity tests showed that hydrogels had good biocompatibility. The prepared P(ACG_x-ACP_y) adhesives has the potential applications to bio-tissue and other wet materials repairing.