Skeletal Editing of Poly(cyclooctene- <i>co</i> -(butadiene- <i>alt</i> -SO ₂ )) via Atom Deletion

Polymer backbones dictate the intrinsic properties and performance of macromolecular materials, yet direct modification of these frameworks after synthesis remains a longstanding challenge. Here, we introduce a postpolymerization atom deletion strategy that converts poly(cyclooctene-co-(butadiene-alt-SO2)) into conjugated polyenes through a one-pot Ramberg–Bäcklund transformation. Under optimized conditions, near-quantitative SO2 extrusion occurs without detectable chain scission─a consequence of the associative reaction pathway. This transformation installs conjugated triene and extended polyene sequences otherwise unattainable by direct polymerization, leading to large changes in the material’s thermal, mechanical, and photophysical properties. Mechanistic studies using a small-molecule analog revealed a microstructure-dependent elimination route that accounts for backbone cleavage at elevated sulfone contents, thereby defining the practical upper limit of sulfolene incorporation during copolymerization. Collectively, these results establish atom deletion as a versatile platform for skeletal editing of SO2-bearing polymers, enabling the postsynthetic reprogramming of polymer structure and function.