ZWITTERIONIC POLYMERS FOR DURABLE ANTIBACTERIAL SURFACES

Antibacterial coatings that combat bacterial attachment and biofilm formation have been intensively studied due to the ever-growing demand on effective and durable antibacterial solutions. Among the most successful strategies against bacterial adherence, zwitterionic polymers have been widely acknowledged as the next-generation antifouling materials due to their excellent nonfouling property and effectiveness against a broad spectrum of bacteria. To date, various techniques were developed to incorporate zwitterionic polymers into coating matrix, but almost none of them demonstrated long-term durability upon mechanical and chemical damage. In our research, the serviceability and longevity of zwitterionic antibacterial coatings were prioritized at the early stage of design. Three approaches were proposed to improve the durability of coatings. we first developed zwitterionic polymer surfaces through simple blending of poly(sulfobetaine methacrylate) (PSBMA)/poly(ether sulfone)(PES) semi-interpenetrated networked microgels with PES polymer matrix. Reduced bacterial attachment and biofilm formation were observed for both E. coli and S. aureus bacteria. The biofilms formed on the coating surfaces were suppressed into small and scattered spots. The mechanical durability with respect to anti-abrasion property and chemical resistance against acidic and alkali solutions demonstrated the feasibility of applying under rigorous conditions. In the second concept, we designed a zwitterionic polyurethane (ZPU) with high content of sulfobetaine zwitterionic moieties which enabled surface hydrophilicity tohydrophobic acrylic polyurethane (APU) via an inter-diffused structure. The diffusion between ZPU and the underlying APU base ensures long-lasting surface hydrophilicity by allowing the zwitterionic moieties to be anchored into the interior of the coating films. In the third concept, active-killing essential oil carvacrol and non-fouling carboxybetaine zwitterionic moieties were combined into “stealthy” mode, followed by incorporation into a bio-based polyurethane (BPU). Long-lasting active-killing property was achieved through the extended-release of bounded carvacrol via hydrolysis in aqueous environment. Also, the release of carvacrol will generate zwitterionic moieties which prevents further bacterial attachment at the release sites, resulting in a “kill and defend” synergistic antibacterial function to the BPU. The purpose of our research is to inspire effective yet durable antibacterial coatings for practical applications.