Investigations of a series of nonionic surfactants of sugar-lipid hybrids by light scattering and electron microscopy

Sugar-lipid hybrids of the type C_nC_m were prepared by coupling an alkane chain (C_n) with a maltooligosaccharide (G_m) over an amide linkage. Coupling was performed with maltobionolactone (G₂) and n-alkylamine chains C_n withn=8,10,12,14,16, i.e. variation of the hydrophobic part of the molecule, and with hexadecylamine (C₁₆) and different maltooligosaccharides (G_m, m=2,3,4,6). The solution properties of the various products were studied by means of static and dynamic light scattering (LS) and by electron-microscopy (EM).The results may be summarized as follows: If the alkane chain is shorter thann=14, small spherical micelles with a radius of about 3 nm are observed. In time these micelles aggregate further to form increasingly larger spherical clusters which eventually precipitate. Long rod-like micelles form whenn 14. Contour length and chain stiffness were determined by applying theories of semiflexible chains. A qualitative confirmation of the light scattering results, i.e., micelle size and shape, was obtained from electron microscopy.