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

Abstract

AbstractThe surface properties [effectiveness of surface tension reduction (γCMC) critical micelle concentration (CMC), efficiency of surface tension reduction (pC20), maximal surface excess concentration (Γmax), minimal area/molecule at the interface (Amin), and the (CMC/C20) ratio] of some 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)xCH2OH, where RC(O)=undecanoyl, lauroyl, tridecanoyl, myristoyl, and x=1,3, and 4, were investigated at 25°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 balance between intermolecular hydrogen bonds and hydrogen bonds formed with water molecules. The fundamental interfacial properties, such as CMC and γCMC and two thermodynamic parameters, standard free energy of adsorption and standard free energy of micellization, were found to be significantly dependent on the hydrophobic acyl chain rather than on the number of CHOH groups in the hydrophilic moieties. By contrast, the practical performance properties were greatly dependent on the nature of the hydrophilic group. As a whole, these surfactants had desirable foaming properties and efficient wetting abilities. Furthermore, synergism in foaming and wetting abilities was observed in a binary mixture of these surfactants with an alkyloxyethylene sulfate.