Zwitterionic Polymer Brush-Functionalized Dual-Crosslinked Hydrogel Via Subsurface-Initiated Atom Transfer Radical Polymerization for Anti-Fouling Applications

Abstract

In this work, a double-network (DN) hydrogel embedded with initiator (HHy-Br) was prepared and then reinforced with Fe3+, after which the antifouling polymer (poly-sulfobetaine vinyl imidazole, PSBVI) was successfully grafted onto the HHy-Br substrate via subsurface-initiated atom transfer radical polymerization (sSI-ATRP) to obtain PSBVI-functionalized HHy-Br (HHy-PSBVI). It has been demonstrated that Fe3+ can increase the crosslinking density of HHy-Br; as a result, the tensile strength of the as-prepared hydrogel was increased from 0.07 to 1.75 MPa, as well as its anti-swelling properties were improved (from 648% to 219%). In addition, the presence of Fe3+ can efficiently promote the sSI-ATRP process. Compared with HHy-Br, the PSBVI-functionalized HHy-Br manifested a significant decrease in friction coefficient, as the grafted high-thickness PSBVI brush (about 200 µm) has excellent hydrophilicity and can form a strong hydration layer for lubrication. Furthermore, the as-prepared HHy-PSBVI also exhibits outstanding antibacterial properties against E. coli (nearly 100% were removed) and S. aureus (99% were removed), as well as a satisfactory antifouling effect against microalgae (93% Dunaliella and 92% Chlorella were removed), which is attributed to the synergistic effect between the strong hydration of the zwitterionic polymer and the good bactericidal effect of the cationic imidazole group.

Keywords: Zwitterionic polymer brushes, Hydrogel, Double-network, Subsurface-initiated polymerization, Antifouling, Antibacterial