Rare-earth-metal catalyzed highly regio- and stereoselective polymerization of terpene-derived conjugated dienes

Abstract

Bio-based polymers synthesized from renewable feedstocks have increasingly gained attention as alternatives to their petrochemical counterparts. Terpenes, with massive reserves in natural products and diverse structural frameworks, are promising as renewable building blocks for sustainable polymers. In this study, we have developed a series of novel terpene-derived conjugated dienes, which contain a terminal vinyl group and a cyclohexenyl moiety, and have successfully achieved their highly 3,4-isoselective polymerization (>99% 3,4-, >99% mmmm) by using an yttrium-based catalytic system, affording high-molecular-weight polymers (up to 167.2 × 10⁴ g mol⁻¹). The resulting polymers exhibited high glass transition temperatures in the range of 70–88 °C and excellent thermal stability as studied by differential scanning calorimetry and thermogravimetric analysis.