Conformational locking dictates the pyrolysis kinetics and degradation profiles of fully bio-based poly(alkylene sebacate)s

Balancing performance, cost, and end-of-life management remains a challenge for sustainable polyethylene alternatives. This work investigates the thermal degradation pathways of fully bio-based poly(alkylene sebacate)s synthesized from sebacic acid and C 2 -C 6 α,ω-alkanediols. By systematically varying diol length and parity, we reveal that the pyrolysis kinetics are fundamentally governed by the interplay between ester dipole alignment and methylene segment length. In poly(ethylene sebacate) (PESe), the combination of antiparallel dipoles and short ethylene glycol segments induces dense inter-chain interactions and a homogeneous activation energy landscape, triggering a single-stage F1 random chain scission. Conversely, polyesters lacking this structural uniformity, whether due to odd-even parity (PPdSe, PPtSe) or extended even-even segments (PBSe, PHSe), preserve the energetic distinction between amorphous and crystalline domains. This phase separation leads to a sequential two-stage F2 to F3 degradation. Beyond programmable thermal stability, these polyesters exhibit tensile strengths comparable to high-density polyethylene (HDPE), resist neutral hydrolysis, yet are susceptible to enzymatic degradation and closed-loop chemical recycling into monomers. These findings establish diol parity and conformational constraints as precise design parameters for tailoring the end-of-life profiles of sustainable polyesters.