Microphase Separation in Segmented Polyurethaneureas Based on Poly (oxypropylene) Containing Poly (oxyethylene) Segment

Microphase separation in segmented polyurethaneureas prepared from poly (oxyethylene)-poly (oxypropylene)-poly (oxyethylene) triblock copolyether was investigated, and their mechanical and blood-compatible properties were discussed in relation with microphase-separated structures. Elemental analysis and infrared spectroscopic measurements showed a regular chemical structure for the present polyurethaneureas having various hard-segment contents. Thermal analysis, dynamic mechanical analysis, and small-angle X-ray scattering (SAXS) measurements confirmed the microphase separation between hard-segment domains and soft-segment martices for all the samples. Hard-segment content little influenced the glass-transition temperature of soft segments, suggesting a well-defined phase separation. On the other hand, the physical properties of the segmented polyurethaneureas were much dependent on the hard segment content, for example, the tan δ peak became broader with increasing hard-segment content, and the SAXS peak shifted to the longer distance of the Bragg spacing. These results suggest that the interface between hard-segment domain and soft-segment matrix becomes thicker with increasing hard-segment content. This might be one of the reasons why the antithrombogenicuty lowered with the increase of hard-segment content.