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. The obtained BNWK@Al2O3/CA not only has a unique vertical thermal conduction network structure, but also exhibits exceptional compressive mechanical strength.