Poly(butylene adipate) functionalized with quaternary phosphonium groups as potential antimicrobial packaging material

Abstract Alkyne-containing poly(butylene adipate) was synthesized and functionalized through the copper catalyzed azide-alkyne “click” reaction with a quaternary phosphonium group, known for their antimicrobial properties. The resulting functionalized polyester was tested for antimicrobial activity both in dispersion by a dynamic shake flask method, and on the surface. In both cases the polyester was found to significantly reduce the cell counts of Escherichia coli . Results showed that the antimicrobial activity was caused by the covalently attached quaternary phosphonium groups and not by freely available residues or unreacted alkyne groups. The presented polymer can, after coating or lamination on a carrier material, show applications as an antimicrobial packaging film for food or medical purposes. Industrial relevance The current study describes a newly synthetized polyester containing covalently bound quaternary phosphonium groups. The resulting polyester showed great antimicrobial activity through direct contact without freely available active groups. Industrially, the presented polyester could be used as an antimicrobial contact layer for food or medical purposes, showing no migration of an active compound to the product.