SURFACE-ACTIVITY OF ABA-TYPE NONIONIC OLIGOSACCHARIDE SURFACTANTS

We report on the surface activity of two novel ABA-type nonionic oligo saccharide surfactant: N,N'-dodecamethylene-bismaltonamide and N,N'-do decamethylene-bis (dextran aldonamide) (DEX-C12-DEX), Surface active p roperties, determined from surface tension measurements, were compared with results for AB-type counterparts containing the same hydrophobic segment, N-dodecylmaltonamide and N-dodecyl dextran aldonamide (DEX-C 12). Surface tension measurements, including analysis of binary surfac tant mixtures of DEX-C12 and DEX-C12-DEX show that the DEX-C12-DEX doe s not form micelles, but induces micelle formation of DEX-C12 at a cri tical total surfactant concentration and diblock mole fraction. We sho w the effects of oligosaccharide chain length and molecular geometry o n surface activity and packing density and, with the aid of molecular models, discuss our results from the viewpoint of surfactant conformat ion. (C) 1997 Academic Press.