Engineering hydrophilic polyethylene and polypropylene surfaces using polymer brushes

Hydrophilic polymeric surfaces are highly desirable, enabling a switch from bacteria-attractive to anti-bacterial substrates and improving adhesion of water-based paints. In this study, hydrophobic PE and PP surfaces were rendered hydrophilic via oxygen plasma treatment, followed by covalent attachment of alkyl bromide initiators and the subsequent growth of PMETA (Poly[2-(methacryloyloxy) ethyl] trimethylammonium chloride solution) and PPEGMA (Poly(Poly (ethylene glycol) methyl ether methacrylate)) brushes. The polymer brushes were synthesized via SI-ATRP to impart hydrophilicity as well as antibacterial properties. AFM, FTIR, and water contact angle measurements confirmed the successful grafting of uniform polymer brush layers on both PE and PP surfaces. Among the modified substrates, the PE-PPEGMA surface prepared after 15 min of oxygen plasma exposure exhibited the highest grafting yield (166.66 µg/cm−2), indicating enhanced brush growth. The antibacterial performance of the brush-modified surfaces was evaluated against the Gram-negative bacterium Pseudomonas aeruginosa. Among all, the PP-PMETA with cationic charge prepared after 15 min of plasma treatment demonstrated59% bacterial inhibition. In addition, the brush-modified PE and PP surfaces also exhibited improved adhesion toward water-based paints. This developed surface modification strategy offers a simple, effective route to enhance the hydrophilicity and functionality of commodity polymers, making them promising candidates for biomedical devices, food packaging, and related applications.