CRITICAL SURFACTANT CONCENTRATION IN THE INTERACTION BETWEEN NONIONIC SURFACTANTS AND POLYACRYLIC-ACID - EFFECTS OF HYDROPHOBIC AND POLYOXYETHYLENE MOIETIES OF SURFACTANTS

In the interaction between polyoxyethylene-type nonionic surfactants and polyacrylic acid (PAA), the binding or complex formation occurred abruptly at a certain surfactant concentration T1 which was lower than the critical micelle concentration (CMC). In two series of surfactants, polyoxyethylene laurylethers and polyoxyethylene myristylethers T1 was independent of the polyoxyethylene chain length and temperature but dependent on the hydrophobic moiety. The complexes are stabilized by a number of hydrogen bonds between polyoxyethylene parts of the surfactants and PAA and by cooperative hydrophobic interaction. The compositions of some complexes were estimated.