Core-Crosslinked Star Copolymers as Viscosity Index Improvers for Lubricants

Core cross-linked star (CCS) copolymers were prepared by reversible addition–fragmentation chain-transfer polymerization according to the arm-first technique and studied as viscosity index improvers for application in hydraulic lubricants. A one-pot two-step synthetic procedure was optimized: starting from PMA arms with a precisely controlled structure three different molecular weights using amounts of either divinylbenzene or ethylene glycol dimethacrylate cross-linking agents, CCS high yield (63 88%) obtained. present weight average values ranging 130,000 420,000 g mol–1 number comprised between 4 13. All samples employed, without any purification step, preparation model lubricant formulations fluid applications. good compromise improvement capability resist chain breaking reactions obtained target 20,000 mol–1. Improved performances respect commercial additive