The increasing demand for sustainable materials has propelled the development of bio-based elastomers derived from renewable terpenes. This study presents the synthesis of high-cis poly(butadiene-co-terpene) copolymers using coordination chain transfer polymerization with neodymium-based catalysts, enabling precise control of molecular weight and microstructure. Two terpene monomers, β-myrcene and trans-β-farnesene, were incorporated up to 45 wt% without compromising the elastomeric 1,4-cis polybutadiene segments. The copolymers were evaluated as impact modifiers in acrylonitrile–butadiene–styrene (ABS) and as vulcanizable rubber formulations. ABS containing bio-based copolymers exhibited distinct rubber morphologies, including elongated and rod-like particles with average particle diameters greater than 1042 nm and rubber phase volume fraction values ≥ 0.49, resulting in improved impact resistance exceeding 580 J/m and elongation at break higher than 12%. Vulcanized rubbers incorporating terpene segments displayed tunable curing kinetics, mechanical properties, and dynamic mechanical behavior, with notable increases in elongation (up to ~520%) and elasticity attributed to lower crosslink density (<1.20 × 10⁻⁴ mol/mL). Additionally, its energy dissipation capacity has been enhanced compared to the high-cis polybutadiene. These findings highlight the potential of terpene-derived bioelastomers as sustainable alternatives to fossil-based rubbers, offering comparable or enhanced performance for engineering polymer applications. The study underscores important structure–property relationships, providing a foundation for further optimization toward industrial adoption.

This study reports the synthesis of high cis-1,4 polybutadiene with a narrow molecular weight distribution (Đ < 2.0) by coordinative chain transfer polymerization (CCTP) using a homogeneous ternary NdV₃/diisobutyl aluminum hydride (DIBAH)/dimethyldichlorosilane (Me₂SiCl₂) Ziegler–Natta catalyst system. The polymerization parameters, notably the monomer-to-initiator ratio ([M]/[Nd]) and the halogen-to-initiator ratio ([Cl]/[Nd]), were systematically varied to define the CCTP operational window. It was found that CCTP conditions are achieved only at low [M]/[Nd] ratios ( 4.0) and impairs CCTP control. These findings challenge previous assumptions that higher halogen concentrations are necessary for CCTP, thereby providing important mechanistic insights for tuning active species and achieving improved polymer architecture. The work demonstrates a viable pathway to control polymer microstructure and molecular weight in neodymium-based CCTP, which is critical for design of high-performance elastomeric materials.