Sustainable High Thermal Conductivity Composites from Biomass: Bio-Based Polyimide/Microencapsulated CNTs for Green Thermal Management

Driven by the miniaturization and integration of electronic components, escalating thermal loads have necessitated the development of materials with high thermal conductivity. However, the direct incorporation of thermally conductive fillers (e.g., carbon nanotubes, CNTs) into polymer matrices often resulted in poor dispersion and interfacial compatibility, thereby limiting overall performance. In this study, a biobased polyimide (Bio-PI) was synthesized from 2,5-furandicarbonyl dichloride (FDCA-Cl2), a biobased FDCA derivative. Carboxyl-functionalized CNTs (c-CNTs) were engineered via SiO2 core–shell encapsulation and ODA modification to obtain surface-functionalized m-CNTs. During composite formation, in situ encapsulation of m-CNTs by the Bio-PI matrix generated self-assembled microcapsule architectures, enhancing filler dispersion and interfacial compatibility to establish stable thermal networks. At 30 wt % loading, PI/m-CNTs-30% achieved a thermal conductivity of 2.00 W/mK, representing an 11.76-fold enhancement over neat Bio-PI (0.17 W/mK). Concurrently, the SiO2 shell maintained balanced dielectric properties (εr = 6.53, tan δ = 0.026 at 1 MHz) and electrical resistivity (7.95 × 1012 Ω·cm). This composite demonstrates significant potential as a heat-dissipating material for electronic devices, particularly in advanced packaging requiring stringent dielectric and insulating performance. This work presents a methodology for fabricating high-performance renewable thermal management materials.