Structure–Performance Relationship Study of PMA Viscosity Index Improver in New Energy Vehicle Transmission Fluid

This study systematically investigates the structure–performance relationship of PMA (PolyMethacrylate) viscosity index improvers in new energy vehicle (NEV) transmission fluids. We developed an integrated analytical framework combining spectroscopic and chromatographic techniques to simultaneously characterize its side chain length distribution, molecular weight polydispersity, and branching architecture. Key findings reveal that the kinematic viscosity of formulated oils positively correlates with PMA molecular weight, low-temperature performance is governed by side-chain length (≥C14 fatty alcohols), shear stability is predominantly determined by molecular weight, and nitrogen-modified PMA enhances oxidation resistance by mitigating kinematic viscosity increase. These insights provide actionable guidance for the molecular design of viscosity index improvers and the formulation optimization of advanced lubricants to meet the stringent demands of electric vehicle transmission systems.