Synthetic Fluorocarbon Betaine Surfactants as Multifunctional Emulsifiers for Creating Highly Stable, Lubricative, and Anticorrosive Emulsions

Emulsion-based lubricants have an advantage in their capacity to combine the characteristics of traditional oil- and water-based lubricants. The major technical challenge to obtain emulsion-based lubricants is to achieve homogeneous mixing of lubricating base oils and water with the assistance of surfactants. Although fluorocarbon surfactants have displayed some specific superiorities to conventional hydrocarbon surfactants in consumer products and other industrial fields, their efficacy as stabilizers and additives for emulsion-based lubricants has seldom been reported. Here we demonstrate that a rationally designed, synthetic fluorocarbon betaine surfactant (termed FAECB-7) can act as a simple and versatile emulsifier for creating highly stable, lubricative, and anticorrosive emulsions consisting solely of paraffin oil, water, and the surfactant by means of, on one hand, attaining low oil/water interfacial tensions and, on the other, generating a tribochemically active adsorbed film on metal surfaces. It was found that the emulsion-based lubricants can be stored for at least three months without noticeable phase separation and provide an enhanced lubrication and anticorrosion relative to the paraffin base oil in the presence of a large amount of weakly lubricative and highly corrosive deionized water. Our study may provide new insights into the design and preparation of novel simplified liquid lubricant formulations with multifunctionality.