Self-Adaptive Non-Flammable Wallpaper With Layered Bead-Network Structure for Light Path Modulation Enabling on-Demand Building Thermal Management.

Self-adaptive materials capable of radiative cooling and solar heating without extra energy consumption have drawn extensive interest. However, limited solar reflectivity in cooling mode and unsatisfactory spectral conversion ability, arising from color residue and weak scattering ability of adaptive color-changing components, restrict their practical application. Herein, a layer-by-layer embedding strategy was proposed, in which thermochromic microcapsules were incorporated layer by layer into a layered network formed by inorganic hydroxyapatite nanowire bundles. The formed multi layered bead-network structure achieved selective layer-by-layer reflection or absorption through light path regulation, overcoming the color residue limitation of thermochromic microcapsules. The obtained wallpaper exhibited a high reflectivity of 94.1% and an emissivity of 95.5% in cooling mode, along with a solar spectral regulation capability of 30.4%. This wallpaper had self-adaptive ability to switch modes in response to temperature changes. In summer, the maximum cooling effect could reach 5°C. Conversely, in cold winter, it achieved a solar heating effect of 8.5°C. Moreover, outstanding flame-retardant and self-cleaning properties of wallpaper eliminated potential safety hazards, and prevented failure caused by contamination of rainwater and dust. This study presents a simple yet efficient approach to integrating contradictory optical properties, and provides a promising solution for building energy efficiency.