Surface properties of N-alkanoyl-N-methyl glucamines and related materials

The surface properties [effectiveness of surface tension reduction (gamma(C MC)), critical micelle concentration (CMC), efficiency of surface tension r eduction (pC(20)), maximal surface excess concentration (Gamma(max)), minim al area/molecule at the interface (A(min)), and the (CMC/C-20) ratio] of so me well-purified N-alkanoyl-N-methyl glucamines and related polyol-based N- methyl amide-type surfactants, having the structural formula RC(O)N(Me)CH2( CHOH)(x)CH2OH, where RC(O)= undecanoyl, lauroyl, tridecanoyl, myristoyl, an d x = 1, 3, and 4, were investigated at 25 degrees C in distilled water and 0.1 M NaCl. Water solubility of these compounds does not simply depend on the number of hydroxyl groups in the molecule but is associated with the ba lance between intermolecular hydrogen bonds and hydrogen bonds formed with water molecules. The fundamental interfacial properties, such as CMC and ga mma(CMC), and two thermodynamic parameters, standard free energy of adsorpt ion and standard free energy of micellization, were found to be significant ly dependent on the hydrophobic acyl chain rather than on the number of CHO H groups in the hydrophilic moieties. By contrast, the practical performanc e properties were greatly dependent on the nature of the hydrophilic group. As a whole, these surfactants had desirable foaming properties and efficie nt wetting abilities. Furthermore, synergism in foaming and wetting abiliti es was observed in a binary mixture of these surfactants with an alkyloxyet hylene sulfate.