Surface-Active Betaines: N-Alkyl-Nn-Dimethylglycines and Their Critical Micelle Concentrations

Abstract

A series of surface-active N-alkyl NN-dimethyl glycines (alkyl betaines) and their hydrochlorides have been prepared. Some physical properties of these compounds have been investigated. The critical micelle concentrations of the betaines have been determined by a surface tension, a refractive index, a dye solubilisation and an iodine method. An explanation of the differences in critical micelle concentrations between these amphoteric surfactants and corresponding anionic and cationic surfactants is proposed.