Synergistic Reinforcement of Butadiene Rubber via Syndiotactic 1,2-Polybutadiene Predispersion: Balancing Modulus, Toughness, and Dynamic Performance

As a novel semi-crystalline elastomer, syndiotactic 1,2-polybutadiene (SPB) grants unique advantages in reinforcing diene elastomers. However, SPB requires high-temperature processing due to its ultrahigh melting point, which leads to substantial energy consumption and risks of oxidation, ultimately degrading material performance. In this work, a SPB@BR predispersion with controlled microstructure was obtained by dispersing SPB toward the end of the solution polymerization of neodymium-catalyzed polybutadiene (Nd-BR). Benefiting from the regular and flexible molecular chain structure and intrinsically low hysteresis characteristics of Nd-BR, SPB undergoes uniform confined crystallization within the rubber matrix, forming a characteristic hard-island/elastic-sea microstructure. SPB microcrystals act as aggregates larger than 100 nm, forming reversible microcrystalline hard domains through confined crystallization within the Nd-BR matrix. This reversible microcrystalline and crosslinking architecture enhances stiffness and effectively inhibits crack propagation while avoiding the excessive restriction of chain mobility typically imposed by permanent rigid constraints. As a result, the cooperative network simultaneously improved mechanical properties (tear strength by 24.4%, modulus by 10.7%, crack resistance by 23.2%) and dynamic performance (rolling resistance reduced by 33.6%, wet skid resistance improved by 21.0%) compared to the references. This work presents a green, effective reinforcing strategy providing a potential pathway for the application in tire sidewall and tire tread materials.