Hierarchically Porous Wood as a Confining Scaffold to In Situ Polymerized Alkyl-Acrylate Phase Change Materials for Photothermal Conversion and Passive Thermal Management

Organic phase change materials (PCMs) are limited in solar thermal applications by leakage and inadequate solar energy absorption. Here, we use in situ polymerization of an alkyl-acrylate monomer encapsulated in delignified wood (DW) and delignified-carbonized wood (DCW) to create wood-based composites. The carbonized scaffold functions as a broadband solar absorber and is leakage-resistant with contact angles up to 133°. The poly(octadecyl acrylate)-infused delignified-carbonized wood (PODA@DCW) composite has the maximum melting enthalpy (102.6 J/g), with delayed cooling, and stable heating/cooling cycle performance for 100 thermal cycles at 80 °C. A photothermal efficiency of 91.4% for the PODA@DCW was observed, with excellent heat storage properties during the cooling and heating processes. Overall, the PODA@DCW composite exhibited efficient photothermal conversion with a high capability of latent heat storage in a sustainable and mechanically robust scaffold, providing a promising candidate for solar thermal energy storage and passive thermal regulation.