NOVEL POLYSACCHARIDE SURFACTANTS - THE EFFECT OF HYDROPHOBIC AND HYDROPHILIC CHAIN-LENGTH ON SURFACE-ACTIVE PROPERTIES

A series of nonionic saccharide surfactants with an amide group linkin g hydrophilic saccharide segment to hydrophobic alkyl segment were syn thesized and their surface active properties were determined. We exami ne the effects of hydrophobic and hydrophilic chain lengths on the sur face active properties and correlate our results to structural differe nces in the saccharide surfactants. N-Alkylmaltonamides were synthesiz ed with hexyl, octyl, decyl, dodecyl, and octadecyl alkyl segments and N-dodecyl aldonamides were synthesized with glucose, maltose, and dex tran (DP = 9) saccharide segments. Increasing the alkyl chain length i n N-alkylmaltonamides decreases the critical micelle concentration, an d increases the efficiency of reducing water surface tension and emuls ification ability, but the effectiveness in reducing water surface ten sion is about the same. Increasing the saccharide size in N-dodecyl al donamides from glucose to maltose to dextran increases the critical mi celle concentration, decreases the efficiency and effectiveness of red ucing water surface tension, but has little effect on emulsification p roperties. We show that the size of the saccharide segment is importan t in determining the interfacial surface area occupied by the surfacta nt molecules. An octyl, decyl, or dodecyl maltonamide occupies about 4 0 Angstrom(2) at the air/water interface, but this increases to 60 Ang strom(2) when maltose is replaced by the larger dextran. (C) 1996 Acad emic Press, Inc.