Mechanically Robust, Recyclable, and Highly Thermally Conductive Ethylene–Propylene–Diene Monomer/Boron Nitride Composite Enabled by Multiple Interfacial Cross-Linking Networks

It is still a great challenge to develop ideal elastic thermal interface materials with high thermal conductivity and excellent mechanical properties for the demand of efficient thermal management materials. Herein, mechanically robust, recyclable, and highly thermally conductive eEPDM/DA@BNMS/ZITA composites were prepared through a dynamic covalent reaction between epoxidized ethylene–propylene–diene monomer (eEPDM) and carboxylated boron nitride microspheres (DA@BNMS), and zinc itaconate (ZITA) was used as a reinforcing filler. The constructed dynamic β-hydroxyl ester bond between eEPDM and DA@BNMS resulted in the enhancement of interfacial interaction, which could achieve transesterification at the interface and endow the composite with a reinforcing effect and dynamic recycling ability, and the reclaimed sample still maintained the higher mechanical properties after the third recycling. ZITA was in situ formed through a neutralization reaction between ITA and ZnO in an eEPDM/DA@BNMS/ZITA composite system, and multiple interfacial cross-linking networks were constructed, which significantly enhanced the mechanical properties, reaching a maximum as high as 14.59 MPa. The thermal conductivity of eEPDM/DA@BNMS reached 1.7 W/mK in terms of the formation of effective thermally conductive paths due to enhanced interfacial interactions, while the thermal conductivity of eEPDM/DA@BNMS/ZITA slightly decreased due to an increase of the interfacial thermal resistance after the incorporation of ZITA. Such a facile strategy shows a promising prospect in preparing mechanically robust and highly thermally conductive rubber composites as ideal candidates in thermal management fields.