• • EEF suppresses backbiting by 2.7-fold, achieving >99% ROMP selectivity at 10 mM monomer concentration, directly mitigating chain termination and enabling high-fidelity linear polymer growth for defect-free materials.
• • Moderate EEFs (0.5–0.8 V) boost Z-selectivity to 97% by stabilizing syn-Ru–Cl configurations, overriding thermodynamic control that typically yields E-isomers; this provides a direct handle for stereochemical programming in precision elastomers and thermoplastics.
• • At 1 V, EEF acts as an on/off switch, abruptly halting ROMP and permitting sequence-defined block copolymer synthesis with single-monomer resolution, as confirmed by quantized photon counts (20 COE → 1 f-COE → 20 COE) and distinct emission spectra (500 nm for f-COE; 550 nm for f-NBE).
• • Fluorescent tracking reveals restricted chain-end mobility in Z-selective chains due to tighter helical packing, correlating stereochemistry with conformational dynamics and offering a non-invasive quality-control metric for industrial polymerization.