Ortho ester‐based cleavable cationic surfactants

Abstract

Abstract A new type of cleavable cationic surfactant, based on the ortho ester link, is described. Ortho ester amines with alkyl chain lengths from C 8 to C 16 were synthesized from a short‐chain ortho ester, a fatty alcohol, and an amino acohol. The ortho ester amine was subsequently quaternized with methyl chloride, yielding a cationic surfactant. The structures were confirmed by 1 H and 13 C nuclear magnetic resonance and the surface chemical properties were investigated by measuring both static and dynamic surface tensions. The results were compared to standard n ‐alkyl trimethyl ammonium bromides. The critical micelle concentrations were found to vary rather widely, whereas the surface tensions in some cases were comparatively low. The short alkyl chain ortho ester quaternaries were found to have low surface tensions at short surface ages and to induce rapid wetting of a hydrophobic surface in dynamic tests. Additionally, the new surfactants were found to hydrolyze rapidly under mild acidic conditions, as measured by both titation and monitoring of the dynamic surface tension. Further, they showed excellent long‐term stability at pH 10 in dilute aqueous solutions. The effect of added electrolyte on rate of hydrolysis was also investigated. A marked enhancement in the hydrolysis rate was found when NaBr was added, whereas NaCl did not have the same effect. The new surfactants could potentially be used to provide temporary surfactant action in application areas such as disinfection, fabric care, personal care, chain lubrication, and mineral flotation as well as in textile processes such as dyeing or scouring.