Saving time and energy in the laundry process: Importance of dynamic surface tension, micelle stability and surfactant adsorption

It has been shown that the residual moisture content of fabrics at the end of a centrifugation cycle is related to the equilibrium surface tension of the residual solution in the fabric. However, in the case of lowering the surface tension of solution via increasing concentrations of sodium dodecyl sulfate, a peak is observed in the residual moisture content and the residual moisture of fabrics deviates from the predictions of the LaPlace Equation of capillary rise. This is due to adsorption of surfactant on the fabric and the increase in dynamic surface tension. Several other molecular mechanisms have been found to affect the residual moisture content of fabrics such as the following: dynamic surface tension, micellar stability, chain length compatibility, surfactant-vesicle interactions as well as monolayer penetration. In surfactant systems with stable micelles, the dynamic surface tension of solution is high compared to labile micellar solutions and the resulting residual moisture content of fabrics is higher than the residual moisture of labile micellar systems. Similarly, when the chain lengths of multiple surfactants in a two surfactant system are of the same length, the micellar stability of this system is much higher compared to mismatched chain lengths. The residual moisture content of fabrics in same chain length surfactant systems has been shown to be higher compared to mismatched chains. It has also been established that monolayer penetration can be used to lower the air-liquid surface tension of solution. In this work, we developed a method to lower the air-liquid surface tension values to values much lower than published results (about 7 mN/m). This method was then used to reduce the residual moisture content of fabrics in the laundry process.