Stretchable heat-dissipation sheet based on insulating graphene and boron nitride composites: asymmetric elastomeric networks for stable thermal conductivity under repeated tensile strain
Sang‐Mi Jeong, Taekyung Lim, Jonguk Yang, Hee Sung Seo, Sanghyun Ju
As modern electronic devices become smaller and more highly integrated, stable thermal management is emerging as a key development approach, including in applications considering mechanical deformation. In this study, a flexible heat-dissipating sheet was developed using composites of insulating graphene (I-Gr), plate-like boron nitride (BN-P), and aggregated spherical BN (BN-A) based on a high-elasticity styrene-(ethylene-butylene)-styrene (SEBS) elastomer. The unique asymmetric two-dimensional layered structure of I-Gr and BN improved the heat transfer properties of the composite by maintaining the continuity of the heat-conducting network despite tensile deformation. In addition, the spherical shape and disordered structure of the aggregated BN-A promoted the formation of an extended heat-conducting path and enhanced the bonding between the fillers. At the optimal composition, the composite maintained an initial thermal conductivity (TC) of 2.0 W m<sup>-1</sup> K<sup>-1</sup> or higher, and the TC reduction (ΔTC) was less than 8% and 10% at 50% and 100% elongation, respectively, demonstrating excellent TC stability. In addition, owing to the interfacial affinity and network reinforcing effect of I-Gr, the TC performance and structural stability were maintained even after 500 cycles of 50% tensile strain and 400% elongation. In contrast, the CNT-based composite showed limitations such as low initial TC, large ΔTC, and low elongation. This study presents a design strategy for a heat-dissipating material with high elasticity, high TC, and excellent durability, offering considerable potential for use in next-generation flexible electronic devices such as wearable electronics, freeform displays, and soft robotics.
https://doi.org/10.1039/d5na00373c
Materials science
Composite material
Boron nitride
Thermal conductivity
Graphene
Elastomer
Composite number
Dissipation
Ultimate tensile strength
Tensile strain
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