Multicomponent Molecular Editing of Polybutadiene: From Design Space to Battery Function

Multicomponent post‐polymerization modification (PPM) enables polymer diversification, yet its potential for exploring structure‐property‐function relationships remains underexplored. Herein, we report an electrophilic multicomponent molecular editing strategy that enables the construction of a polybutadiene‐derived molecular design space through systematic variation of cyclic ethers and N ‐ or O‐ nucleophiles. Combining three cyclic ethers with six nucleophiles generated an 18‐member library, varying spacer architecture, polarity, and intermolecular interactions ( P1 ‐ P18 ). Mapping thermal, selected morphological, and molecular mobility properties revealed substantial changes arising from subtle molecular variations. In particular, P9 was distinguished by its nanoscale organization and proton relaxation behavior, providing insight into the influence of molecular structure on morphology and molecular dynamics. Mapping these complementary property landscapes guided the selection of P11 for preliminary evaluation as an electrolyte additive for Li–S batteries, based on its balance of functionality and physicochemical properties. Electrochemical testing in a deliberately LiNO 3 ‐free model electrolyte revealed that P11 altered sulfur redox behavior and impedance response, increased Coulombic efficiency, and showed more gradual capacity decay relative to the additive‐free baseline, albeit with increased polarization and reduced initial capacity. These trade‐offs demonstrate library‐guided selection without establishing P11 as an optimized additive. Descriptive sensitivity analysis identified nucleophile identity as the dominant input for functionalization degree (FD) and thermal stability, whereas glass‐transition temperature showed sensitivity to both molecular inputs.