An oriented layered Nano-CaCO3 with enhanced fire resistance and acoustic insulation performance for building insulation

Abstract

Contemporary building insulation materials not only require low thermal conductivity but also need to possess high flame retardancy and excellent acoustic insulation properties. Typically, organic materials excel in thermal and acoustic insulation, while inorganic insulation materials demonstrate superior flame retardancy. Therefore, combining the advantages of organic and inorganic materials to achieve high insulation, excellent flame retardancy, and acoustic insulation performance is of great significance but remains challenging. Herein, a strategy driven by coordination bonds is proposed to form a nano-CaCO₃ composite chitosan (CS) oriented layered structure, which is used to prepare Flame-retardant Nano-CaCO₃/oriented Layered Chitosan composites (FNCLC). Benefiting from the stability of the lamellar structure, the prepared FNCLC exhibits excellent mechanical properties. The gaps in the oriented lamellar structure contain a large amount of air, which interrupts the solid heat transfer path, resulting in excellent insulation performance (0.096 W m⁻¹ K⁻¹). The nano-CaCO₃ endows FNCLC with superior flame retardancy, with a limiting oxygen index (LOI) of up to 99.12 %. Additionally, the oriented lamellar structure effectively reflects sound, with FNCLC achieving acoustic insulation exceeding 40 dB in the mid-frequency range. Thus, this strategy of using coordination bonds to drive nano-CaCO₃ composite CS oriented lamellar structures provides new insights for constructing building insulation materials.