STRUCTURAL INVESTIGATION OF WATER LECITHIN/CYCLOHEXNAE MICROEMULSIONSBY FT-IR SPECTROSCOPY/

FT-IR spectra of water/lecithin/deuterated cyclohexane microemulsions as a function of water/lecithin molar ratio R (R = [water]/[lecithin]) at various volume fractions (O) of the micellar phase have been recor ded at 25 degrees C. After elimination of the small spectral contribut ions due to deuterated cyclohexane and normalization, the shape of the C-H stretching band due to lecithin has been found dependent upon R a nd 0 whereas that of the O-H stretching band has been found dependent only upon R. The change in shape of the C-H band was interpreted in te rms of a modification of the lecithin alkyl chain packing order. The a nalysis of the O-H band provides evidence that the hydroxylic groups o f lecithin form strong hydrogen bonds whereas the added water is confi ned in bulk-like water domains. (C) 1995 Academic Press, Inc.