Aggregation of morpholinium surfactants with amino alcohols as additives: a close look

Abstract

Mono-, di- and triethanolamine in combination with methylmorpholinium and hydroxyethylmorpholinium surfactants were investigated for their aggregation and solubilizing properties. A co-operative behavior of the solubilization by mixed surfactant–ethanolamine systems is described. Ethanolamines strongly affect pH and lead to Orange OT phenolic group deprotonation and subsequent increase in aqueous/micellar solubility. The morpholinium surfactant micelles reduce the pK a of the Orange OT phenolic group, enabling its deprotonation at the earlier stages of medium alkalinization. The obtained surfactant–ethanolamine mixtures can solubilize very large amounts of hydrophobic dye, which can then be triggered to precipitate through acidification.