Dual functional star polymers for lubricants

Star-shaped poly(alkyl methacrylate)s (PAMAs) with a three arm architecture were designed, prepared and their performance as a dual additive (viscosity index improver and friction modifier) for engine oils was evaluated. Furthermore, the structure-property relationships between the macromolecular structure and lubricant performance were studied, such as molecular weight and polarity effects on the viscosity index. Several co-polymers of dodecylmethacrylate with polar methacrylates in various amounts and various topologies, were synthesized as model compounds. Star polymers with a polar content of at least 10% in a block or tapered block topology effectively reduced the friction coefficient in both mixed and boundary lubrication regimes. However, a polar content of 20% was efficient in reducing friction in both random and block topologies.