Preparation of highly efficient thermal insulating halloysite nanotubes/polyvinyl alcohol composite aerogel based on a simple freeze-drying strategy

The development of high-performance energy-saving insulation materials is significant for reducing building energy consumption and promoting carbon neutrality. Aerogels show great potential in energy-saving insulation. However, their high preparation cost and poor mechanical properties limit their application. Here, based on a simple freeze-drying strategy, a halloysite nanotubes (HNTs)/polyvinyl alcohol (PVA) composite aerogel is achieved via low-cost and degradable industrial raw material. In particular, a simple process for changing the properties of HNTs/PVA composite aerogels by regulating the solid concentration. As a result, stable covalent cross-linking and hydrogen bonding structure between HNTs and PVA, long-range ordered pore structure with high porosity (97.6%), low density (0.12 g/cm 3 ), and low thermal conductivity (44.333 mW/m K) endow the HNTs/PVA composite aerogel high compressive strength (3.33 MPa), lightweight, and highly efficient thermal insulation properties. This work offers an attractive material for building insulation and carbon neutral.