Structure–protein adsorption relationships of polyurethanes

A series of hydroxyl-terminated polybutadiene (HTPB) and 4,4′-dicyclohexylmethane diisocyanate (H₁₂MDI)-based polyurethanes (PUs) with different molecular weight, hard-segment content, or 4-vinyl pyridine content (4-VP content) were synthesized by solution polymerization. Protein adsorption ratio of fibrinogen to albumin (F/A molar ratio), which was adopted as the indicator of blood compatibility, was measured. The F/A molar ratio on the film's surface was affected by surface composition. The surface composition was quantified by carbonyl group to butadiene group (C=O/C=C) adsorption ratio on FTIR-ATR spectra and oxygen to carbon atom (O/C) ratio, which was determined by ESCA. PUs with more hard-segment content on the surface (i.e., high C=O/C=C ratio) possess more fibrinogen adsorption and less albumin deposition (i.e., high F/A molar ratio). The C=O/C=C ratio, hydrogen-bonding index (HBI value), frequency shift and difference (Δν), glass transition temperature of soft segment (T_gs) as a measure of homogeneity, average strength of interpolymer hydrogen bonds, and interpenetrating networks (IPNs) were utilized to study the surface composition, intermolecular attraction, and IPN formation of the prepared PUs. The effect of hard-segment content, molecular weight or 4-VP content on the F/A molar ratio were investigated. The results of FTIR and ESCA explain well the surface composition, and hence, the F/A molar ratio as well. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 74: 297–305, 1999