Hydrogenated Styrene–Diene Copolymers as Thickening Additives to Lubricating Oils

Classes of styrene–diene copolymers used as thickenining (viscosity) additives to lubricating oils are considered. Specific features of the synthesis and hydrogenation of such copolymers are discussed. The main requirements to thickening additives and the molecular structure–property relationships for the thickening power and viscosity index, mechanical stability, ability to disperse carbon black particles, heat resistance, and low-temperature properties are analyzed. The main producers of thickening additives based on hydrogenated stryrene–diene copolymers are presented.