Crosslinked-Polymer Brushes with Switchable Capture and Release Capabilities

Cross-Linked Polymer Brushes Containing N-Halamine Groups for Antibacterial Surface Applications

Microbial contamination is a significant issue in various areas, especially in the food industry. In this study, to overcome microbial contamination, cross-linked polymer brushes containing N-halamine were synthesized, characterized, and investigated for antibacterial properties. The cross-linked polymer brushes with different N-halamine ratios were synthesized by in-situ cross-linking methods with reversible addition-fragmentation chain transfer (RAFT) polymerization using a bifunctional cross-linker. The RAFT agent was immobilized on an amine-terminated silicon wafer surface and utilized in the surface-initiated RAFT polymerization of [N-(2-methyl-1-(4-methyl-2,5-dioxoimidazolidin-4-yl)propane-2-yl)acrylamide] (hydantoin acrylamide, HA), and N-(2-hydroxypropyl)methacrylamide) (HPMA) monomers. Measurement of film thickness, contact angle, and surface morphology of the resulting surfaces were used to confirm the structural characteristics of cross-linked polymer brushes. The chlorine content of the three different surfaces was determined to be approximately 8-31 × 1013 atoms/cm2. At the same time, it was also observed that the activation-deactivation efficiency decreased during the recharge-discharge cycles. However, it was determined that the prepared N-halamine-containing cross-linked polymer brushes inactivated approximately 96% of Escherichia coli and 91% of Staphylococcus aureus. In conclusion, in the framework of this study, high-performance brush gels were produced that can be used on antibacterial surfaces.

Surface-Grafted Polymeric Ionic Liquids with Tunable Morphology via In/Ex Situ Cross-linking Methods

Surface-grafted poly(ionic liquid) (PIL) films were prepared by both in and ex situ cross-linking methods with reversible addition-fragmentation chain transfer (RAFT) polymerization. Cross-linked brushes are more stable than linear brushes without sacrificing the surface functionality and, therefore, have increased potential for applications in biomedicine and materials chemistry. The two methods, in situ via a bifunctional cross-linker and ex situ via thermal cross-linking, were systematically compared on silicon-wafer substrates. Films obtained through in situ cross-linking were superior to films derived from our ex situ cross-linking technique with respect to responsive behavior and controlling the formation of polymer brushes on the surface. Alternatively, more stable layers were obtained by the ex situ cross-linking method using a cross-linker based on Meldrum's acid, where the film structure could be changed from a brush to collapsed film morphologies with an increasing cross-linker ratio.