Multifunctional Hyperbranched Polyester From <scp>CO₂</scp>‐Derived Inimer and <i>ε</i>‐Caprolactone: Synthesis, Characterization, and Functionalization

ABSTRACT α ‐Ethylidene‐ δ ‐vinyl‐ δ ‐valerolactone (EVL), a substituted δ‐lactone synthesized through the telomerization of CO 2 with 1,3‐butadiene, is highly functionalized, containing a six‐membered ring and two CC double bonds. In this contribution, we report the copolymerization of 3‐(1‐(2‐hydroxy ethylthio) ethyl)‐6‐vinyl valerolactone (HEVL), an inimer derived from EVL, with ε ‐caprolactone ( ε ‐CL) to yield a novel multifunctional hyperbranched copolyester, P(HEVL‐ co ‐CL). The structure of P(HEVL‐ co ‐CL)s was characterized by 1 H, 13 C, 13 C‐ 1 H HSQC, 1 H‐ 1 H COSY NMR, MALDI‐ToF MS, and SEC‐MALS. The simultaneously initiating and ring‐cleavage of HEVL facilitates the formation of a hyperbranched topology of the copolymers. The influences of monomer feed ratio, monomer concentration, reaction time, and temperature on the copolymerization, along with the composition and architecture of the copolymer, were investigated. The P(HEVL‐ co ‐CL) exhibits distinctive molecular characteristics, featuring an abundance of tailored functionalities, enabling the synthesis of polyester microspheres and polyurethane elastomers via thiol‐ene and hydroxyl‐isocyanate cross‐linking post‐polymerization modifications. This protocol significantly expands the potential for developing advanced sustainable materials from CO 2 and olefin‐based feedstocks.