Design and characterization of self‐healing waterborne acrylic coatings with <scp>CNT</scp> ‐enhanced microcapsules

Abstract This study presents the development of a novel self‐healing waterborne acrylic coating incorporating linseed oil‐filled ethyl cellulose (EC) microcapsules modified with oxidized carbon nanotubes (OxCNTs). The OxCNTs were functionalized via amidation using 2‐(1 H ‐benzotriazole‐1‐yl)‐1,1,3,3‐tetramethyluronium tetrafluoroborate (TBTU) and conjugated with fluorescein isothiocyanate to form fluorescent CNT probes (CNTP), enabling microcapsule surface tracking. The new methodology offers several advantages, including higher yields, lower reaction temperatures, and shorter reaction times, supporting the applicability of TBTU in similar reactions. Incorporating CNTP improved interfacial interactions, mechanical interlocking, and fluorescence traceability. Optical microscopy, scanning and transmission electron microscopies; and Fourier transform infrared, UV–visible, and fluorescence spectroscopies confirmed the successful fabrication and functionalization of CNTs and microcapsules. Coatings containing 1 wt% OxCNT@EC microcapsules demonstrated optimal self‐healing performance by restoring mechanical properties and reducing water vapor transmission after surface damage. Released linseed oil facilitated healing via auto‐oxidative crosslinking, effectively sealing microcracks effectively. The proposed system offers a promising approach for durable, eco‐friendly coatings with built‐in self‐repair capabilities. © 2026 Society of Chemical Industry.