Effects of thermal annealing of segmented-polyurethane on surface properties, structure and antithrombogenicity.

Analyses of the surface structure and properties of thermally heat-treated and non-treated segmented-polyurethane (SPU) surfaces showed that a crystalline structure, the domain size of which was larger than that of the micro-phase separation structure, appeared when the SPU surface was annealed in the temperature range of 60-140 degrees C. The appearance of the crystalline structure resulted in a decrease in surface free energy, that is, an increase in the hydrophobicity of the surface. Whole blood or platelet-rich plasma (PRP), when in contact with a SPU surface, which had previously been in contact with a glass surface during casting, coagulation of the whole blood occurred within approximately 30 min and, in case of PRP, in approximately 60 min. When the SPU surface was modified by thermal annealing, the coagulation time for PRP was delayed, whereas that of whole blood remained essentially unchanged. Relationships between the surface properties and the structure of annealed SPU and antithrombogenicity are discussed. The data collected herein suggest that the heat treatment of SPU might be useful for improving antithrombogenicity.