Sequential Dual Alignments Introduce Synergistic Effect on Hexagonal Boron Nitride Platelets for Superior Thermal Performance

Yunxia Chen; Zhiming Gao; Simon A Hoo; Varun Tipnis; Renjing Wang; Ivan Mitevski; Dale Hitchcock; Kevin L Simmons; Ya-Ping Sun; Malisa Sarntinoranont; Yong Huang

doi:10.1002/adma.202314097

Sequential Dual Alignments Introduce Synergistic Effect on Hexagonal Boron Nitride Platelets for Superior Thermal Performance

Adv Mater. 2024 Mar 11:e2314097. doi: 10.1002/adma.202314097. Online ahead of print.

Authors

Affiliations

¹ Department of Mechanical and Aerospace Engineering, University of Florida, Gainesville, FL, 32611, USA.
² Oak Ridge National Laboratory, 1 Bethel Valley Road, Oak Ridge, TN, 37830, USA.
³ Savannah River National Laboratory, Savannah River Site, Aiken, SC, 29808, USA.
⁴ Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, WA, 99354, USA.
⁵ Department of Chemistry, Clemson University, Clemson, SC, 29634, USA.
⁶ Department of Materials Science and Engineering, University of Florida, Gainesville, FL, 32611, USA.

PMID: 38466829
DOI: 10.1002/adma.202314097

Abstract

Planarly aligning 2D platelets is challenging due to their additional orientational freedom compared to 1D materials. This study reports a sequential dual-alignment approach, employing an extrusion-printing-induced shear force and rotating-magnetic-field-induced force couple for platelet planarly alignment in a yield-stress support bath. It is hypothesized that the partial alignment induced by a directional shear force facilitates subsequent axial rotation of the platelets for planar alignment under an external force couple, resulting in a synergistic alignment effect. This sequential dual-alignment approach achieves better planar alignment of 2D modified hexagonal boron nitride (mhBN). Specifically, the thermal conductivity of the 40 wt% mhBN/epoxy composite is significantly higher (692%) than that of unaligned composites, surpassing the cumulative effect of individual methods (only 133%) with a 5 times more synergistic effect. For 30, 40, and 50 wt% mhBN composites, the thermal conductivity values (5.9, 9.5, and 13.8 W m^-1 K^-1 ) show considerable improvement compared to the previously reported highest values (5.3, 6.6, and 8.6 W m^-1 K^-1 ). Additionally, a 3D mhBN/epoxy heat sink is printed and evaluated to demonstrate the feasibility of device fabrication. The approach enables the planar alignment of electrically or thermally conducting 2D fillers during 3D fabrication.

Keywords: 3D embedded printing; dual alignments; hexagonal boron nitride; synergistic effect; yield-stress support bath.

Abstract

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