Preparation of waste-incorporated bio-smart shape-stable phase change material (FSSPCM) with responsive fluorescent properties

Abstract

Shape-stable phase change materials (SSPCMs) are excellent for thermal energy storage applications. This study presents the first novel fluorescent switchable bio-smart SSPCMs incorporating waste. We used poly(ethylene glycol) (PEG) as the phase change material combined with leather waste (LW) and poly(glycidyl methacrylate) (PGMA). These composites achieved a relatively high shape fixity ratio (62–70%) and 100% shape recovery in both air (70 °C) and water (37 °C). They remained stable over a wide temperature range (−28.2 to 220 °C) and had high phase change enthalpies (86.8–149.7 J g⁻¹). Composite PGL721 fully healed at 70 °C within 1.5 hours. By adding fluorescein and rhodamine B to PGL721, we created smart fluorescent SSPCMs, namely, FSSPCM1 and FSSPCM2. FSSPCM1 exhibited ON–OFF–ON fluorescence with heating, while FSSPCM2 showed ON–OFF fluorescence in the presence of Fe³⁺ ion (0.7 M). These smart fluorescent materials have promising applications in biomedical, textile, and soft robotic sensors and thermal storage application.