Properties of the Quaternary Ammonium Salts with Novel Counterions

The Krafft temperatures, surface tensions and bacteriostatic efficacies of a series of dodecyl/tetradecyltrimethylammonium salts with new type counterions based on the general formula RN+(CH3)(3) A(-) were measured. The results revealed that the Krafft temperatures of the studied products were below 0 A degrees C and the surface tensions of water were decreased to 22-42 mN m(-1) when applying these surfactants at a concentration range from 10(-2) to 10(-4) mol L-1. Moreover, the physicochemical parameters such as the saturation adsorption value, the minimum area per surfactant molecule and the standard thermodynamic parameters of adsorption and micellization varied with different counterions for these prepared quaternary ammonium salts. In addition, the bacteriostatic tests showed that the counterions with shorter carbon chain lengths were associated with greater efficacy for the novel quaternary ammonium salts studied here.