Hydration Mechanism in Blood-Compatible Polymers Undergoing Phase Separation

Interactions involving intermediate water are crucial for the design of novel blood-compatible materials. Herein, we use a combination of atomic force microscopy, quartz crystal microbalance measurements, and soft X-ray emission spectroscopy to investigate the local hydrogenbonded configuration of water on blood-compatible poly(2-methoxyethyl acrylate) and non-blood-compatible poly(n-butyl acrylate) grafted on a gold substrate. We find that the initially incorporated water induces polymer-dependent phase separation, facilitating further water uptake. For the blood-compatible polymer, tetrahedrally coordinated water coexists with water adsorbed on C=O groups in low-density regions of the grafted polymer surface, providing a scaffold for the formation of intermediate water. The amount of intermediate water is determined by the type of functional groups, local polymer configuration, and polymer morphology. Thus, blood compatibility is governed by the complex water/polymer interactions.

Automated summary

In this study, the local hydrogen-bonded configuration of water on blood-compatible and non-blood-compatible materials was investigated. The presence of water induced phase separation in the materials, facilitating further water uptake. The amount of intermediate water was influenced by functional groups, polymer configuration, and morphology. These complex water/polymer interactions are crucial for blood compatibility.