Catalyst-free synthesis of antibacterial poly(ethylene succinate) with gemini quaternary ammonium salts

Polyesters are widely employed in textiles, packaging, and biomedical materials owing to their excellent mechanical properties, chemical stability, and cost-effectiveness. However, synthesizing inherently antibacterial polyesters remains challenging. Traditional methods often rely on metal catalysts, risking cytotoxic metal residues, while conventional polyesters lack intrinsic antibacterial activity and require additives. Inorganic antibacterial agents may pose toxicity concerns, and organic agents frequently degrade during high-temperature processing. To address these limitations, this study developed thermally stable, polymerizable gemini quaternary ammonium (GQA) salts as antibacterial comonomers. Using catalyst-free melt polycondensation, we synthesized an antibacterial poly(ethylene succinate) (PES) with antibacterial groups covalently bonded to the polymer backbone. The resulting material retained thermal and mechanical properties comparable to pure PES. Notably, incorporating just 0.05 mol% of the GQA comonomer achieved near-complete (>99.9 %) antibacterial efficacy against both Staphylococcus aureus and Escherichia coli. This metal-free, scalable approach enables the production of high-safety antibacterial polyesters suitable for critical applications such as food packaging and biomedical devices.