Construction of highly thermally conductive epoxy composites via magnetic field-induced alignment of multi-dimensional hybrid BN/CNT fillers

Multidimensional thermal fillers significantly enhance composite thermal conductivity. • The magnetic responsiveness of Fe 3 O 4 -loaded BN pre-modified with KH-560 and PSS was compared. • Magnetically modified fillers achieve oriented alignment under an external magnetic field. • The thermal conductivity of EP/mBN10C5 was 0.574 W/(m·K), representing a 134% increase over pure EP. • These epoxy-based composites demonstrate significant potential for electronic thermal management applications. To address the inherently low thermal conductivity of polymer composites in electronic thermal management, this study proposes a strategy for constructing thermal conduction networks through magnetic field-induced alignment of multi-dimensional fillers. During magnetic modification, the pre-modification effects of poly(sodium 4-styrenesulfonate) (PSS) and silane coupling agent KH-560 on the filler surface were first compared. Experimental results indicated that the fillers pre-modified with PSS exhibited a coercivity of 59 Oe and a relative Fe content of 5.59% after magnetic modification, demonstrating superior magnetic responsiveness. After introducing Fe 3 O 4 onto the filler surface, a continuous thermal conduction pathway was constructed by combining external magnetic field alignment with hybrid filling of multidimensional fillers. Herein, two-dimensional magnetic boron nitride (mBN) constituted the thermal skeleton, with one-dimensional magnetic carbon nanotubes (mCNTs) bridging the gaps to create a continuous thermal network. When 5 wt% of mCNTs was introduced into the composite containing 10 wt% mBN, the thermal conductivity increased by 134% relative to EP, reaching 0.574 W/(m·K). Furthermore, thermogravimetric analysis results demonstrated that the incorporation of mCNTs effectively reduced the maximum mass loss rate of the composites. This work demonstrates the potential of magnetically aligned multi-dimensional fillers to optimize thermal networks, establishing a foundation for low-filler, high-thermal-conductivity composites in thermal management. Download: Download high-res image (214KB) Download: Download full-size image