Preparation and evaluation of high-performance modified poly(ester-amide), and study its biological activity after its formulated as a vehicle for protective coating.

Poly(ester-amide) (PEA) resins are widely used in coating applications because of their excellent mechanical strength, chemical resistance, and durability; however, the development of PEA coatings with enhanced antimicrobial performance remains a significant challenge. In this study, a novel modified PEA resin was synthesized using 3-N-bis(2-hydroxyethyl)-7-hydroxy coumarin carboxamide (HEHCCA) as a reactive modifier. To the best of our knowledge, the incorporation of HEHCCA into PEA coating systems has not been previously reported. The modified resins were prepared by partially replacing hydroxyethyl linseed oil fatty acid amide (HELA) with HEHCCA, while phthalic anhydride was used as the polyacid component. The prepared resins were formulated into coating systems and characterized according to standard ASTM methods to evaluate their physicochemical, mechanical, chemical, and antimicrobial properties. The results showed that increasing HEHCCA content increased the reaction time, viscosity, color intensity, and drying time of the coatings. Mechanical properties such as gloss, impact resistance, scratch hardness, and adhesion improved noticeably, whereas flexibility remained nearly unchanged. The coatings also exhibited good chemical resistance except under alkaline conditions. In addition, the modified PEA resins demonstrated significant antimicrobial activity, particularly against Staphylococcus aureus and Klebsiella pneumoniae, with inhibition zones reaching 24.15 ± 0.30 mm. These findings suggest that HEHCCA-modified PEA resins are promising candidates for advanced protective and antimicrobial coating applications.