Adsorbed Water Structure on Acrylate-Based Biocompatible Polymer Surface

The role of water in the excellent biocompatibility of the acrylate-based polymers widely used for antibiofouling coating material has been realized previously. Here, we report femtosecond mid-infrared pump-probe spectroscopy of the OD stretch band of HOD molecule adsorbed on highly biocompatible poly(2-methoxyethyl) acrylate [PMEA] and poorly biocompatible poly(2-phenoxyethyl) acrylate [PPEA], both of which reveal that there are two water species with significantly different vibrational lifetime. PMEA interacts more strongly with water than PPEA through the H-bonding interaction between carbonyl (C=O) and water. The vibrational lifetime of the OD stretch in PPEA is notably longer by factors of 3 and 7 than those in PMEA and bulk water, respectively. The IR-pump visible-probe photothermal imaging further unravels substantial spatial overlap between polymer CO group and water for hydrated PMEA and a significant difference in surface morphology than those in PPEA, which exhibits the underlying relationships among polymer-water interaction, surface morphology, and biocompatibility.

Automated summary

The study reveals that water molecules adsorbed on highly biocompatible and poorly biocompatible acrylate-based polymers have different vibrational lifetimes, with PMEA showing stronger H-bonding interaction with water and PPEA exhibiting notably longer OD stretch vibrational lifetime. The results also demonstrate substantial spatial overlap between polymer CO group and water for hydrated PMEA, as well as a significant difference in surface morphology compared to PPEA, highlighting the underlying relationships among polymer-water interaction, surface morphology, and biocompatibility.