Boron nitride whiskers and nano alumina synergistically enhancing the vertical thermal conductivity of epoxy-cellulose aerogel nanocomposites

With the continuous innovation of electronic information technology, thermal interface materials, which mainly play the role of heat dissipation in microelectronic devices, will face great challenges. In this work, the boron nitride whiskers (BNWK)@Al₂O₃/cellulose aerogels (CA) were obtained by electrostatic self-assembly one-dimensional BNWK and zero-dimensional nano-Al₂O₃ combined with directional freezing of CA. The obtained BNWK@Al₂O₃/CA not only has a unique vertical network structure but also exhibits exceptional compressive mechanical strength, especially when the mass ratio of BNWK/nano-Al₂O₃ is 1:7. The compressive strength of BNWK@Al₂O₃(1:7)/CA reaches 97 kPa. Based on the flexibility of the CA and the support of the rigid hybrid filler BNWK@Al₂O₃, the theoretical relaxation time of the composite is also as high as 25,327 s. Furthermore, the thermal conductivity of the epoxy-based composite (BNWK@Al₂O₃/CA/EP) with a filler loading of 8.6 wt% is about 1.92 W/(m·K), which is 9.6 times that of pure EP; the excellent thermally conductive property is due to the accelerated phonon transport by the vertically arranged BNWK@Al₂O₃ network structure. Hence, this work provides a new idea for developing a new generation of thermal interface materials. Graphical abstract: The obtained BNWK@Al₂O₃/CA not only has a unique vertical thermal conduction network structure, but also exhibits exceptional compressive mechanical strength. [Figure not available: see fulltext.].