Nonionic Micelles

Abstract

Abstract Current theories and recent results on the thermodynamics of micelle formation and the structure of micelles of nonionic surfactants in water are reviewed. The experimental results are in favor of the mass-action model of micelle formation. This model predicts the existence of micelles below the critical micelle concentration (cmc) and a gradual transition at the cmc. The cmc, as determined conventionally, depends on both the association number, N, and the equilibrium constant, nKc of closed association on a mole basis. Empirical' relationships between N and nKc have been found for n-octyl-β-D-glucoside (OG) and two nonylphenol(ethylene glycol)x ethers (NP) at various temperatures as well as for four different ethylene glvcol acrylamides (EMA) CH2˭C(CH3)-CO-NR-(CH2)10-CO-(OCH2CH2)15-OCH3The equilibrium constants of association can be determined by different molecular weight methods, even in the case of polymolecular unimers. Extrathermodynamic relationships exist between the enthalpies and entropies of association.