Development of High-Performance Polyurethane Biomaterials

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Since segmented liquid crystalline polyurethanes (LCPUEs) have a liquid crystalline hard segment, LCPUEs expected to show a unique behavior in mechanical and biomedical performances. The purpose of this study is to investigate the applicability of LCPUEs for biomedical field. Following subjects have been studied in 1993 and 1994.1) Synthesis and characterization of LCPUESegmented liquid crystalline polyurethanes (LCPUEs) with the hard segments composed of the mesogen 4,4'-bis (6-hydroxyhexoxy) biphenyl and toluene diisocyanate (TDI), and the soft segments composed of poly (tetramethylene oxide) (PTMO) with various molecular weight have been prepared. Differential scanning calorimetric and wide angle X-ray diffraction study revealed that the endotherm at 403K corresponding to the isotropization transition.2) Surface structure analysis of LCPUESince biomaterials have been used in an aqueous environment, a freeze-etch X-ray photoelectron spectroscopic technique has been developed. This te … More chnique revealed the surface enrichment of hydrophilic component at the water-solid interface.3) Evaluation of surface thermal molecular motion of LCPUESurface structure of LCPUEs was studied on the basis of X-ray photoelectric spectroscopy (XPS), and the atomic force microscopy (AFM). As-cast LCPUE showed the smooth flat surface with nanometer scale. Annealing of LCPUE at 378K induced the ordering of mesogenic hard segment. Annealing of LCPUE with PTMO (Mn=2000) showed the increase in surface roughness. The scanning viscoelasticity microscopic (SVM) measurement was carried out in order to confirm the presence of phase-spparated structure on the surface of LCPUE with PTMO (Mn=2000). SVM revealed that bump was mainly composed of rubbery PTMO phase. This characteristic surface morphology was formed due to the ordering of hard segment being accompanied the increase in conformational entropy of PTMO segments.4) Interaction between plasma protein and LCPUEThe interactions between plasma protein and microphase-separated surface have been studied on the basis of ATR-IR flow cell technique and AFM.AFM results revealed the domain recognized adsorption of plasma protein. Less