SURFACE AND BULK STRUCTURE OF SEGMENTED POLY(ETHER URETHANES) WITH PERFLURO CHAIN EXTENDERS .5. INCORPORATION OF POLY(DIMETHYLSILOXANE) AND POLYISOBUTYLENE MACROGLYCOLS

Nonpolar hydrophobic soft segments were synthetically incorporated into polyurethanes based on 4,4'-methylenebis(phenyl isocyanate) (MDI)/hexafluoro-1,5-pentanediol (FP)/poly(tetramethylene glycol) (PTMO). The soft segments incorporated were dihydroxy-terminated poly(dimethylsiloxane) (PDMS) and polyisobutylene (PIB). All soft segments have similar molecular weights (M(n) almost-equal-to approximately 2000). All polymers prepared also have similar levels of hard segment (approximately 55 wt %), and they are soluble in common organic solvents. The solvent-cast polymers were studied by Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry, electron spectroscopy for chemical analysis (ESCA), and static secondary-ion mass spectrometry (SSIMS). The FTIR analysis showed that the absorption band at 3295 cm-1 is important for the interpretation of soft-segment mixing behavior in segmented poly(ether urethanes). The surface analysis data revealed that the incorporation of 20 wt % or less of PIB or PDMS in the soft segment may be sufficient to completely cover the polymer surface with each corresponding soft segment. The PDMS polyurethanes exhibited a pronounced casting solvent dependence on the surface and bulk structure, while the PIB polyurethanes showed less dependence on casting solvent.