Bio-composites with efficient heat dissipation and excellent EMI shielding by constructing bamboo fiber/MWCNT dual network structure

Abstract

Traditional electromagnetic shielding materials primarily address electromagnetic interference (EMI) but overlook excessive heat accumulation caused by the miniaturization and high-frequency operation of integrated electronics. This thermal buildup compromises device lifespan, stability, and reliability, restricting their applicability in heat-sensitive applications. In this study, heterogeneous dual-network bio-based composites (BPC/MWCNT) exhibiting high thermal conductivity, EMI shielding effectiveness, and mechanical strength were fabricated via lignin regeneration technology, utilizing lignin as a structural bridge. The BPC/MWCNT biocomposites demonstrate outstanding mechanical properties, achieving tensile and flexural strengths of 53.28 MPa and 60.58 MPa, respectively. This property originates in the melt-regenerated in-situ lignin acting as a green binder under high-temperature/-pressure conditions, forming a robust adhesive interface via interfacial hydrogen bonding, π-π stacking, and mechanical interlocking, thereby reconciling the mutually repulsive properties. Notably, the biocomposite exhibits a thermal conductivity of 1.03 W m⁻¹ K⁻¹, surpassing conventional wood and bamboo materials by a significant margin. This enhanced performance arises from a dense three-dimensional dual-network BPC/MWCNT structure formed through high-temperature compression. Despite the inherently low thermal conductivity of bamboo fibers, the architecture facilitates efficient heat conduction and dissipation at the interface between the highly conductive MWCNT and bamboo fibers. Furthermore, the incorporation of MWCNT improves electrical conductivity and delivers an EMI shielding effectiveness of 73.8 dB. The three-dimensional dual-network architecture achieved via this sustainable strategy offers a viable solution to address simultaneous thermal accumulation and EMI challenges in integrated electronics.