Hierarchically porous and flexible BN/Co-MOF aerogel encapsulated paraffin for efficient dual-thermal insulation

Abstract

Thermal insulation and temperature control are extremely important in numerous human activities. Traditional aerogels with low thermal conductivity are known to facilitate good insulation. Boron nitride (BN) aerogels consist of nanoscale nanofiber units with plentiful porous structures, possessing excellent thermal/electrical insulation and chemical stability. However, these porous materials cannot effectively block heat transmission, despite their low thermal conductivity. Therefore, it is necessary to develop a new insulation strategy and explore materials with excellent thermal insulation performance, with special attention to heat transmitted not only through air, but also through thermal regulation by thermal adsorption. Phase change materials (PCMs) are considered promising latent heat storage materials due to their large heat storage capacity, making them promising candidates for highly efficient thermal insulation. However, the flammability of organic PCMs and their susceptibility to leakage during the solid-to-liquid transition seriously limit their wide application. In this study we combined the dual-thermal insulation performance of BN fiber aerogels and PCMs and constructed novel flexible and multifunctional composites with excellent thermal insulation performance using Co-MOF nano-flower cross-linked BN aerogels as interconnected porous substrates to encapsulate paraffin wax (PW) PCMs. The composites exhibited the advantages of BN, Co-MOFs and PCMs, overcoming the drawbacks of single-component materials. The results showed that the latent-heat storage capacity of the BN/Co-MOF/PW composites reached 188.11 J g⁻¹ and the resulting thermal conductivity was as low as 0.0397 W (m⁻¹ K⁻¹), due to high thermal insulation performance. The morphology, flexibility, mechanical performance, and flame retardancy of the constructed BN/Co-MOF/PW composites were systematically investigated, ensuring that the composites could be used for thermal insulation and flame-retardant applications.