Bioinspired gallic acid derivatives for enhanced waterborne acrylic adhesives

Bio-based and environmentally friendly adhesives represent a major trend in the future development of adhesive technologies. This study developed a sustainable bio-based modification strategy to enhance waterborne acrylic adhesive performance through a novel monomer (G-HEMA), synthesized via p-toluenesulfonic acid-catalyzed esterification of bio-derived gallic acid (GA) with hydroxyethyl methacrylate (HEMA). Semi-continuous emulsion polymerization was employed to fabricate adhesive formulations containing 0.1–1.0 wt% G-HEMA. Rheological analysis demonstrated simultaneous enhancement of initial tack and cohesive strength. At the optimal 0.5 wt% loading, the modified adhesive exhibited a maximum peel strength of 17.74 N/25 mm, which is an increase of 120% compared with the unmodified sample. Mechanistic analysis revealed that G-HEMA enhanced both the cohesive strength and initial tackiness of the acrylic adhesive, while also promoting hydrogen-bond interactions with SUS304 substrates to improve bonding strength. This work provides a bioinspired technology for developing high-performance adhesives with dual functionality as reactive monomers and polymerization regulators. The dual functionality of G-HEMA as both a reactive monomer and a polymerization regulator highlights a bioinspired strategy, offering potential applications in packaging, electronics, and eco-friendly manufacturing.