Designing of carbon nanohorn-based heterostructure for improved mechanical properties, flame retardancy, and hydrophobicity of composite aerogels

Developing flame-resistant thermal insulation aerogels with strong mechanical properties is crucial for addressing the fire hazards in high-rise buildings. Carbon nanomaterials have garnered significant attention for enhancing the flame retardancy and mechanical properties of polymers due to their safety, nontoxicity, and low additions. In this work, the effect of single-walled carbon nanohorns (SWCNHs) on the mechanical properties, thermal insulation properties, thermal stability, flame retardancy, and hydrophobicity of polyvinyl alcohol/KH560/phytic acid composite aerogel (PKASx) was investigated. By adjusting the concentration of SWCNHs, the mechanical properties of the aerogel were significantly improved, owing to robust interactions between SWCNHs and the matrix. However, a declining trend was observed in both the compressive modulus and specific modulus when the quantity of SWCNHs exceeded 0.3%. Simultaneously, the PKAS0.3 aerogel exhibited remarkable flame retardancy and self-extinguishing characteristics. It possessed a high LOI value of 34.2 ± 0.2%, with a 25.2% reduction in pHRR and an 18.6% reduction in THR. Moreover, the analysis of TSP and SPR curves affirmed that the inclusion of SWCNHs effectively minimized the production of gaseous by-products during combustion. In addition, the introduction of SWCNHs introduced a trade-off in the roughness of the aerogel. The maximum contact angle occurred at the optimal concentration of SWCNHs.