Preparation of caffeic acid grafted poly(D,L-lactide)-b-poly(2-hydroxyethyl methacrylate)/polylactide films with bioactive properties

Abstract

Derived from renewable sources like corn starch or sugarcane, poly(lactic acid) (PLA) presents an eco-friendly alternative to traditional petroleum-based plastics. PLA lacks inherent functional groups, posing a challenge for certain applications. The modification and functionalization of PLA contribute to the facilitation of innovative applications across diverse fields. To address this limitation, in this study a bioactive compound, caffeic acid, strategically grafted the onto poly(D,L-lactide)-b-poly(2-hydroxyethyl methacrylate) block copolymer (PLA-b-PHEMA). The resulting caffeic acid grafted copolymer (PLA-b-PHEMA-g-CA) was characterized by size exclusion chromatography, NMR, UV–Vis and FT-IR spectroscopies, and then blended with commercial PLA to produce films. The synthesis involves polymerizing 2-hydroxyethyl methacrylate with a poly(D,L-lactide) macroinitiator via ATRP method, yielding PLA-b-PHEMA. Subsequent functionalization via Steglich esterification yields PLA-b-PHEMA-g-CA. Characterization indicated a grafting ratio of 60.7%. Both grafted copolymer and films exhibited antioxidant property and antimicrobial effect against S. aureus and E. coli, showcasing potential applications in sustainable materials.