Malonic Ester Synthesis-type Polymerization: Precise Design of the Repeating Unit Structure in sp³ Carbon-Chain Polymers

Repeating unit structures (RUS) govern polymer function, yet methods to diversify RUS in sp³ carbon‑chain polymers remain limited, particularly for systematic control of side‑chain spacing. Here, we report malonic ester synthesis–type polymerization (MESP), an A₂+B₂ polycondensation that exploits nucleophilic substitution between malonate enolates and alkyl bromides to access sp³ carbon‑chain polymers with single‑carbon increments in side‑chain spacing. Post‑polymerization decarboxylation converts gem ‑bis esters into mono‑ester side chains, yielding acrylate–ethylene copolymer analogues with controlled composition and sequence. Thermal analysis reveals polymer properties spanning amorphous to semi‑crystalline regimes, with odd–even effects arising from single‑carbon variations in gem -bis ester placement relative to methylene units. By unifying backbone and side‑chain design within a single strategy traditionally associated with polyesters and polyacrylates, respectively, MESP expands the accessible RUS landscape and provides a platform for the discovery of new functional carbon‑chain polymers through precise control of functional group arrangement and spacing within their RUS.