Robust <scp><i>β</i></scp>‐myrcene block copolymer elastomeric vitrimers

Abstract As a terpene‐based conjugated diene, β ‐myrcene (Myr) is a promising renewable building block for synthetic rubbers. However, the high entanglement molecular weight of poly(Myr) limits its mechanical properties and applications. This work aims to improve the mechanical properties and dimensional stability of recyclable bio‐based Myr elastomers by incorporating vitrimer chemistry and block copolymer self‐assembly. Linear prepolymers of statistical and diblock terpolymers of Myr, styrene (S) and β ‐ketoester functional (acetoacetoxy)ethyl methacrylate (AAEMA) were synthesized using nitroxide‐mediated polymerization. The resulting statistical (P(S‐ co ‐Myr‐ co ‐AAEMA)) and diblock (PS‐ b ‐P(Myr‐ co ‐AAEMA)) prepolymers had comparable number‐average molecular weights ( M n ~ 20–27 kg mol −1 ) and similar overall compositions. PS‐ b ‐P(Myr‐ co ‐AAEMA) underwent microphase separation into lamellae, as confirmed by small‐angle X‐ray scattering and atomic force microscopy. Vinylogous urethane vitrimers were formed by crosslinking the AAEMA units in the prepolymers with vegetable oil‐derived difunctional amines (Priamine 1075). The networks could be remolded by hot pressing at 125 °C at least 4 cycles while retaining thermomechanical properties. PS‐ b ‐P(Myr‐ co ‐AAEMA) exhibited a tensile stress of 3.1 ± 0.6 MPa, which was four times higher than that of P(S‐ co ‐Myr‐ co ‐AAEMA). The diblock vitrimer also exhibited nearly ten times higher hardness, and similar strain at break ( ~ 90%), compared to the statistical terpolymer‐based vitrimer. The addition of glassy PS domains effectively anchored the network, resulting in 18–35% lower creep in PS‐ b ‐P(Myr‐ co ‐AAEMA). This work highlights the potential of Myr‐based block copolymer vitrimers in creating robust, bio‐based and recyclable elastomers. © 2025 The Author(s). Polymer International published by John Wiley &amp; Sons Ltd on behalf of Society of Chemical Industry.