Utilization of biomass for commodity polymers has gained tremendous interest. We report a method to prepare high molecular weight renewable homopolymers and block copolymers derived from natural rosin. Monomers with high renewable content (70 wt %) were prepared via a simple esterification reaction between dehydroabietic alcohol and 5-exo-norbornenecarboxylic acid. Living and controlled polymerization of these monomers were achieved by ring-opening metathesis polymerization to obtain polymers with molecular weight up to ∼500 kg/mol. These homopolymers exhibit structure-dependent glass transition temperatures, excellent thermal stabilities, and thermoplastic properties. Chain entanglement molecular weight was determined via rheological assessments for such polymers with bulky side moieties. Using the living ROMP, dehydroabietic-based homopolymer was chain-extended with a soybean oil-derived norbornene monomer to yield triblock copolymers, which showed behaviors of thermoplastic elastomers.
Bibliographical noteFunding Information:
The authors acknowledge the support from National Science Foundation (DMR-1252611). X-ray work was carried out at South Carolina SAXS Collaborative supported by the NSF Major Research Instrumentation program (DMR-1428620). We thank H. N. Lokupitiya for the assistance with the SAXS measurements. M.LR. and W.D. acknowledge financial support by the National Science Foundation through Grant DMR-1351788.