Observing the repulsion layers on blood-compatible polymer-grafted interfaces by frequency modulation atomic force microscopy.

Blood-compatible materials that do not promote reactions in contact with human blood are required to support emerging medical technologies. The interfaces of poly(2-methoxyethyl acrylate) (PMEA), a blood-compatible polymer, and its analogues were investigated by frequency modulation atomic force microscopy (FM-AFM). The grafted polymers exhibited phase separation into polymer-rich and water-rich domains. Thin repulsive layers of hydrated polymer chains were observed in the water-rich domains of the blood-compatible polymers; on the other hand, such layers were not observed for the non-blood-compatible polymers. We report for the first time that FM-AFM enables characteristic repulsive layers composed of hydrated polymer chains in water-rich domains to be observed, which is a significant design factor for blood-compatible polymers.