Synergistic Sodium Dodecylbenzenesulfonate/Polydopamine Modification of Multiwalled Carbon Nanotubes: Regulating Dispersion and Interface for High‐Performance NR / BR Tire Sidewall Composites

As the most flexible tire component, the sidewall compound requires high tear resistance and adequate thermal conductivity to reduce performance variations caused by nonuniform vulcanization. In this study, a natural rubber/butadiene rubber (NR/BR) blend was used as the matrix. Sodium dodecylbenzenesulfonate (SDBS) and polydopamine (PDA) were employed to synergistically modify multiwalled carbon nanotubes (MWCNTs). SDBS initially improved MWCNTs dispersion via electrostatic repulsion, while PDA deposition introduced active groups (catechol, quinone, amino) that enhanced interactions with the rubber matrix, improving dispersion and interfacial adhesion. This strategy effectively utilized the thermal conductivity and mechanical reinforcement potential of MWCNTs, thereby enhancing tear strength and thermo‐oxidative aging resistance. Results showed that incorporating SDBS/PDA/MWCNTs increased thermal conductivity and tear strength to 0.3135 W/(m K) and 48.5 kN/m, respectively, with a tensile strength retention of 98.6%. Compared with the MWCNTs‐free system, these values increased by 100.06%, 29.67%, and 21.42%, respectively. This study provides an effective MWCNTs modification strategy for improving NR/BR composite performance and highlights its potential in high‐performance tire sidewall compounds.