Robust Boron Nitride Metamaterials with Negative Poisson's Ratio for Dual Thermal Management Strategies

Abstract

Aerogel and its phase change composites are two reliable strategies for thermal management. However, the inherent instability of these porous structures hinders their further development and application. Herein, a robust boron nitride metamaterial (BNM) enhanced by the negative Poisson's ratio effect is proposed for dual thermal management strategies obtained by the sacrificial template method. The negative Poisson's ratio confers enhanced structural stability to the BNMs. On the one hand, the BNM exhibits resilience (5% residual strain after 100 cycles), temperature invariance, fire resistance, and thermal superinsulation at high temperatures (102.83 mW·m⁻¹·K⁻¹ at 1000 °C). On the other hand, the robust BNM overcomes structural deformation during the vacuum impregnation process to obtain isotropic phase change composites, achieving efficient thermal conductivity (1 W·m⁻¹·K⁻¹ with 4 vol% BNM) and thermal conductivity enhancement effect of 97%. These composites effectively encapsulate phase change materials, preventing liquefaction and leakage. This approach offers a reliable solution for simultaneously improving both the thermal management strategies.