Phase studies of a urethane model compound and polyether macroglycols by infrared spectroscopy and the relationship between eutectic composition of soft segment and blood compatibility.

The binary mixtures of a urethane model compound, diethyl 4,4'-methylenebis(N-phenylcarbamate) (MDU), and various polyether macroglycols have been investigated mainly by infrared (IR) spectroscopy. The mixtures of macroglycol and MDU showed two C=O bands (free C=O at higher wave number, hydrogen bonded C=O at lower wave number), and the intensity of free C=O increased while that of hydrogen bonded C=O decreased linearly with increasing molar ratio of macroglycol/MDU. The slope of the increase or decrease suddenly changed at the specific molar ratio around the eutectic composition. The eutectic molar composition for PTMO1000/MDU was determined as 1.15 or 1.1 by differential scanning calorimetry (DSC) or infrared (IR) studies while that for PTMO3000/MDU as 0.345 or 0.55 by DSC or IR, respectively. The eutectic compositions for other sets were determined by IR studies as follows: PEO1000/MDU, 0.4; PEO3000/MDU, 0.16; PPO1000/MDU, 1.4; PPO3000/MDU, 0.45. The number of ethylene oxide, tetramethylene oxide, and propylene oxide units to form a eutectic with MDU calculated from these values were 15-20, 10-11, and 23-24, respectively. The similar DSC or IR changes were observed in the various kinds of polyurethanes such as MDI/BD, MDI/PTMO/BD, and MDI/PTMO polymers. The relationship between the eutectic compositions of soft segments (MDI/macroglycol) and the ideal Mn of the macroglycols in blood compatibility of segmented polyurethanes are discussed.