PLA-derived lactate esters as plasma precursors for hydrophilic and antibacterial coatings

Abstract

plasma deposition

surface modification

antibacterial properties

polylactic acid ester

polymeric material

This study introduces a novel concept of using lactate esters as unconventional, bio-based precursors for plasma-assisted deposition of multifunctional coatings. Unlike traditional plasma precursors, simple molecules such as methyl and ethyl lactate enable simultaneous enhancement of surface hydrophilicity and antibacterial activity on PET substrate. This work highlights a new pathway for designing advanced functional coatings using readily available ester-based compounds. Plasma deposition induced pronounced changes in surface chemistry and morphology through fragmentation–recombination mechanisms, leading to a significant increase in hydrophilicity, with the water contact angle decreasing from 76° to 27° for ethyl lactate and to 51° for methyl lactate. X-ray photoelectron spectroscopy confirmed the formation of oxygen- and nitrogen-containing functional groups, while the modified surfaces exhibited strong antibacterial performance, achieving up to 3.4 log reduction against Escherichia coli and 2.3 log reduction against Staphylococcus aureus (ISO 22196:2011). Crucially, this work establishes lactate esters as a new and versatile class of plasma precursors, demonstrating that waste-derived, low-molecular-weight compounds can outperform conventional systems in simultaneously imparting hydrophilicity and antimicrobial functionality, thereby redefining their role in plasma processing and providing a scalable platform for multifunctional coatings within a circular economy framework.