Preparation of an antibacterial poly(ionic liquid) graft copolymer of hydroxyethyl cellulose

Poly(ionic liquid)s (P(IL)s) of different degrees of polymerization (10, 50, and 100) were prepared via RAFT polymerization using an alkyne-terminated xanthate as transfer agent, with a monomer conversion of up to ∼80% and a ĐM of 1.5 for P(IL)100. Subsequently, P(IL) chains were coupled to 15N-labeled azido-functionalized hydroxyethyl cellulose (HEC), forming graft copolymers of HEC with different chain length and graft densities, which were characterized using (13C and 15N) CP-MAS NMR and FT-IR spectroscopies. The antibacterial activities of HEC-g-P(IL)s were tested against Escherichia coli and Staphylococcus aureus and were comparable to ampicillin, a well-known antibiotic, demonstrating efficient activity of the graft copolymers against bacteria. Moreover, HEC-g-P(IL)s were slightly more effective against E. coli than S. aureus. A decrease in graft density of P(IL)10 on the HEC backbone decreased the activity of the graft copolymers against both bacteria. These findings suggest that HEC-g-P(IL) could find applications as an antiseptic compound, for example, in paint formulation