Photocurable cellulose-based composites with PEGylated graphene oxide for leakage-free thermal energy storage and photothermal applications.

The development of efficient, reliable, and sustainable energy storage technologies is essential for addressing the growing global demand for clean energy solutions. This study presents a novel approach for enhancing thermal energy storage and photothermal energy conversion through the fabrication of photocurable cellulose-based composites. Methylcellulose (MC) was chemically modified via allyl chloride grafting to improve water resistance and mechanical stability while enabling photocuring. Polyethylene glycol (PEG) was incorporated as a phase change material (PCM) alongside PEGylated graphene oxide (GO) to enhance thermal conductivity and photothermal performance. The resulting porous composite foams, produced via freeze-drying, demonstrated remarkable structural integrity, thermal stability, and leakage-free PCM containment. The optimized composite with 9 wt% PEGylated GO exhibited a porosity of 75 %, a bulk density of 177 kg/m3, and a compressive strength of 4.53 MPa. Additionally, the thermal conductivity increased to 0.82 W/m·K-significantly higher than the control sample without PEGylated GO. Thermal cycling tests confirmed a latent heat enthalpy of 91 J/g, which remained stable after 100 heating-cooling cycles. The composites also exhibited excellent photothermal performance under simulated sunlight, making them promising candidates for renewable energy applications such as solar thermal energy harvesting, passive heat management in electronics, and energy-efficient building materials. This work contributes to the advancement of sustainable materials for thermal energy storage while supporting the development of clean and efficient energy systems in line with global energy transition goals.