Boron nitride nanosheet embedded bio-inspired wet adhesives with switchable adhesion and oxidation resistance

Abstract

Smart adhesives that can debond from a surface on-command in response to stimuli are highly desired. However, the over-oxidation of mussel-mimetic adhesives greatly reduces free-catechol groups and results in an irreversible cross-linked network, especially in alkaline environments. Driven by the synergistic effects of reconstructive Schiff base equilibrium and adjustable dimethylaminoethyl methacrylate (DMAEMA) wettability, an insulated and bactericidal mussel-mimetic nanocomposite adhesive is developed with switchable adhesion and oxidation resistance. Amino-decorated boron nitride nanosheets serve as adhesive building blocks, which can interact with aldehyde group-terminated PEG side chains to form pH-responsive Schiff base networks in situ, reinforcing the cohesion of the adhesive. The alkaline-induced hydrophobic DMAEMA, displaying oxidation inhibiting effects, is subtly incorporated; it can maintain sufficient free-catechol groups to provide desirable adhesion and hinder the irreversible crosslinking of catechols. After acid treatment, the debonding of imine linkages together with acid-induced hydrophilic DMAEMA can drastically decrease bonding strength. Besides, the unique electric properties of BNNSs and the inherent antibacterial activity of Schiff bases endow the as-prepared adhesive with additional prominent functionality, such as high breakdown strength, a low dielectric constant, low dielectric loss and superior bactericidal effects against both Gram-positive and Gram-negative bacteria. This multifunctional adhesive may possess extensive applications in the biomedical and marine industries.