Plastic photothermal composite phase change materials for intelligent greenhouse thermoregulation

Phase change materials (PCMs) are reusable, environment-friendly temperature control materials that can reduce energy consumption and carbon emissions in greenhouse operations. However, the inherent rigidity and leakage of solid–liquid PCMs limit their practical application. In this work, a plastic, form-stable PCM was fabricated by in-situ encapsulation of phase change wax (PCW) and expanded graphite (EG) composites into a three-dimensional (3D) network crosslinked by calcium ions and sodium alginate. The 3D porous network provides high porosity (82.5%) and addresses the rigidity of traditional PCMs, improving their adaptability and applicability while promoting processability and ease of use. EG and the 3D network provide form stability to PCW through hierarchical synergistic encapsulation. Additionally, EG endows the composites with photothermal conversion properties. Based on the excellent performances, applying the composites in greenhouses remarkably reduced temperature fluctuations inside. This exploration offers a significant path for developing green and low carbon greenhouse energy conservation strategies.