Surface properties and restructuring of a crosslinked polyurethane–poly(amido-amine) network

Surface analysis of a new heparinisable material (PUPA) based on polyurethane (PU) and poly(amido-amine)(PAA) components has been performed by ATR FTIR, ESCA, SIMS and AFM measurements, on both dry and hydrated states. This analysis demonstrated that, as for PU, the PUPA surface is enriched in the soft-segment phase in air. Despite its crosslinked nature, PUPA underwent surface restructuring in aqueous media, as demonstrated by ATR FTIR, ESCA and AFM measurements, and the hydrophilic, high-energy component (PAA) migrated to the surface. This reorientation process is reversible and involves only the outermost surface layers.