Ring-opening reaction of maleic anhydride with an amino-end derivative of sulfobetaine methacrylate for effective, versatile and stable fabrication of bacteria and blood-resistant porous polymeric films

Abstract

Background

The maleic anhydride groups of styrene maleic anhydride (SMA) can serve as precursors for subsequent surface modification of polymeric films aimed at generating zwitterionic interfaces for biofouling mitigation. For effective zwitterionization reaction and antifouling properties of the film, the zwitterionic derivative must also possess amino-end or hydroxyl‑end groups.

Methods

We synthesized a derivative of sulfobetaine methacrylate containing amino-end groups, 4-((3-aminopropyl)dimethylammonio)butane-1-sulfonate, from the reaction between a diamine, 3-(dimethylamino)-1-propylamine, and 1,4-butane sultone. Meanwhile, poly(vinylidene fluoride) (PVDF) films containing SMA, were prepared by phase inversion of the PVDF/SMA/solvent blend. The obtained films were then grafted with the zwitterionic material by ring-opening reaction of the maleic anhydride groups.

Significant Findings

After ring-opening reaction between the SMA copolymer molecules embedded in the PVDF matrix and the amino-end group zwitterionic reactants, the hydration of the membranes was significantly improved with a water contact angle falling to 0° in dynamic tests while it remained constant to about 143° for the virgin membrane. This important hydration enhancement resulted in outstanding bacterial resistance in static conditions against Escherichia coli (E. coli), Stenotrophomonas maltophilia, Staphylococcus aureus and Streptococcus mutans (97 % to 99 % reduction, relative to the unmodified sample). Resistance to E. coli after 3 weeks of immersion remained as high as 98 %, suggesting stability of the modification ensured by the hydrophobic interactions between PVDF and styrene groups of SMA. During flow, irreversible biofouling by E. coli was reduced from over 87 % (in unmodified films) to 55 %, the reversible fouling decline ratio increased from <8 % to about 35 % suggesting weakened interactions between bacteria and the films after the modification. Finally, the water permeability recovery of the porous film increased significantly from 12.6 % to 45.0 %.