pH-Responsive Intelligent Antibacterial Coatings Based on 2D-COF for Controlled Release of Capsaicin

Herein, we designed and synthesized a two-dimensional covalent organic framework (2D-COF) of a Schiff base using a mechanical chemical grinding method. Moreover, capsaicin@chitosan (CAP@CS) microcapsules were loaded on a TpPa-1 COF by a physical adsorption method to prepare composites (CAP@CS/TpPa-1), which realized the pH-sensitive controlled release of the fungicide CAP, dispersed in fluorocarbon resin to prepare an intelligent coating with environmentally friendly long-term antifouling performance. TpPa-1 improves the antibacterial efficiency by increasing the dispersity of CAP@CS in the resin. Therefore, a CAP release amount of 2 wt % composite coating can meet the minimum bacteriostatic concentration of 37.5 μg/mL required for antifouling. Importantly, pH-responsive controlled release caused by the protonation of CS and the electrostatic interaction between CAP@CS and TpPa-1 COF and increased bacterial contact area by CAP@CS reunion inhibited by TpPa-1 COF improve the bactericidal efficiency of the composite. The composite coating has excellent corrosion resistance, mainly because COF extends the propagation path of the corrosive medium.