Grafting of epoxidized natural rubber chains with BN platelets to obtain flexible and thermally conductive papers

Abstract

Owing to the rapid development of high-power and minimized electronic devices, the materials with ultra-flexibility and effective heat dissipation have attracted much interest. Herein, the high thermally conductive epoxidized natural rubber (ENR) papers with layered structures based on boron nitride (BN) platelets are reported. First, polyrhodanine (PRd) was coated on the surface of BN platelets via oxidative polymerization of rhodanine (Rhd), which was initiated by the absorbed (S2O8)2- ions. Then, BN-PRd platelets were grafted with ENR chains using a mechanochemical method due to the presence of N–CS groups in PRd, allowing the combination of PRd and ENR chains with stable covalent bonds. Moreover, the grafted ENR chains acted as bridges between adjacent BN platelets and improved the heat transfer ability of BN-PRd/ENR thermally conductive composite papers. The as-prepared ultra-flexible 30 wt% BN-PRd/ENR thermally conductive composite papers rendered high in-plane (λ∥) and through-plane (λ⊥) thermal conductivity of 14.57 and 0.52 W/(mK), respectively, which were correspondingly 8094% and 289% of pure ENR paper (0.18 W/(mK)). Also, Young's modulus of the 30 wt% BN-PRd/ENR thermally conductive composite paper was 25.90 MPa. Overall, the as-fabricated BN-PRd/ENR thermally conductive composite papers demonstrated high flexibility, excellent mechanical robustness, outstanding thermal conductivity, and superior electronic illustration, indicating potential applications in areas of electronic components as thermal interface materials.