Photothermal energy conversion and storage with lignocellulose-polyethylene phase change polymer

For building complexes in low-latitude regions, the efficient storage and conversion of high-intensity solar energy remain a significant challenge. Although building energy-efficient phase change materials (BEE-PCMs) offer a potential solution, their practical application is often limited by component leakage and poor material compatibility, which typically necessitate high packaging costs. In this work, a low-cost packaging strategy is proposed by physically entangling cross-linked phase change polymers (PCPs), lignocellulose (LE) and low density polyethylene (LDPE), resulting in a green modified PCP (MPCP). Among these, MPCP-6 with 6 wt% LE exhibits excellent mechanical properties, with a tensile strength of 3.9 MPa, compressive strength of 62.4 MPa, and toughness of 30.7 kJ/m 3 —equivalent to 487.5 %, 515.7 %, and 874.6 % of the unmodified PCPs, respectively. Furthermore, MPCP-6 possesses intrinsic anti-leakage capability and demonstrates remarkable thermally induced flexibility, achieving 720° curl deformation at 50 °C. Compared to commercial machine-made concrete blocks (CMB) and epoxy-enhanced PCM (EPCM) modules, MPCP-6 exhibits superior thermal responsiveness. The peak indoor temperature is reduced to 37.6 °C, which is 2.2 °C and 3.0 °C lower than that of EPCM and CMB modules, respectively. This work provides a promising strategy for improving thermal comfort in buildings located in low-latitude regions.