Controlling intermicellar exchange: Strong-stick and weak-stick collisions in hydrocarbon media

AEI 35

Jianzhong Fu, Chemical and Biomolecular Engineering, Tulane University, 300 Boggs Center, New Orleans, LA 70118
Base nanoparticles are present in engine oil for controlling corrosive wear by neutralizing combustion-generated acids. The nature of these base particles and the transport of base and/or acid in oil determine the success in protecting engine corrosion. The surfactants stabilizing these nanoparticles, also known as overbased reverse micelles, may be present as (i) dynamically exchangeable and (ii) tightly bound molecules. Dependent on the extent of dynamic exchange, strong/weak-stick collisions are proposed to drive the base and acid transfer in oil media. A strong-stick collision occurs when the dynamically exchangeable surfactant molecules are involved in a stick collision and desorbed, resulting in a fast base transfer; while a weak-stick collision happens when such desorption cannot occur, then a slow acid transfer is expected. The ratio of dynamically exchangeable molecules to the total stabilizing surfactants determines the frequency of strong-stick collisions, thus may be used to tailor intermicellar exchange rates.