Synthesis of a Stretchable Polyampholyte Hydrophilic Film with Compositional Gradient for Long‐Term Stable, Substrate‐Independent Fouling‐Resistant Coating

The prevention of nonspecific biofouling is crucial for technological development in biomaterials and medical devices. Thus, zwitterionic materials have attracted significant attention due to their effective fouling-resistance, long-term durability against oxidation, and biocompatibility. However, fabricating a substrate-independent zwitterionic surface with outstanding fouling-resistance remains a challenge. In this study, a polyampholyte coating that satisfies the aforementioned requirements is obtained using a vapor-phase method. The polyampholyte coating consists of a bilayer of poly(1,3,5,7-tetramethyl-1,3,5,7-tetravinyl cyclotetrasiloxane) (pV4D4) and polyampholyte, poly(2-carboxyethyl acrylate-co-2-(dimethylamino)ethyl acrylate) (pCD), stacked with compositional gradient, which are obtained via sequential deposition using initiated chemical vapor deposition. The heavily crosslinked pV4D4 acts as an adhesion promoter layer that may be applied conformally to various substrate materials with high interfacial adhesion. The pCD surface exhibits a long-lasting, superior fouling-resistance to proteins (20.3 ± 1.8 ng cm−2 for undiluted human serum) and microorganisms. The pCD-grad-pV4D4 films, coupled with the stress-dissipative gradient interface, are highly stretchable up to 50% without compromising the fouling-resistance. The fouling-resistance is maintained after 1 day of sonication, 10 days of water flushing, and 30 days of water shearing. Further, the pCD-grad-pV4D4 films are fully transparent and patternable, making them a prospective alternative for future non-fouling biomedical applications.