Large scale production of catalyst-free poly(ethylene succinate) with intrinsic antibacterial property through the design of hyperthermostable quaternary ammonium monomers

It will be a significant advance if polyesters exhibit intrinsically antibacterial property considering their wide usage in the biomedical field, non-woven fabrics and food storage. Given the poor durability and low efficiency of physically blending or post-modification with antibacterial agents, melt polycondensation using polymerizable antibacterial agents as comonomer is potentially the most versatile and efficient approach for large scale production of polyesters with intrinsic antibacterial property. However, organic antibacterial agent fails to be used as comonomer for melt polycondensation due to its poor thermal property. Herein, a facile and green strategy is proposed for the synthesis of quaternary ammonium monomers via the reaction between sodium 5-sulfoisophthalic acid and various quaternary ammoniums in water, producing a series of antibacterial monomers with the highest thermal degradation temperature up to 361 °C. Finally, antibacterial poly(ethylene succinate) (PES) was synthesized via catalyst-free melt polycondensation from ethylene glycol and succinic acid using 1-hexadecyl-3-methylimidazolium 5-sulfoisophthalic acid as comonomer. The resultant functionalized PESs exhibit comparable physiochemical properties to pure PES, with additional superior and persistent antibacterial activity. This work provides a feasible strategy for the large scale production of antibacterial polyesters through in-reactor engineering.