Structure–Functionality-Integrated Composite Phase Change Materials with Reversible Thermochromism and Enhanced Mechanical Stability

Abstract Phase change materials (PCMs) have exhibited favorable prospects in thermal energy storage and thermal management systems. However, it is highly desirable to overcome the drawbacks of bulk PCMs, including inherent leakage problem, low thermal conductivity, and single heat-storage functionality. Therefore, a reversible thermochromic composite PCM with high energy storage capacity, good reliability, and anti-leakage performance was developed by synergistic assembly through inter-molecular hydrogen bonds and interconnected cross-linking. The synergistic cross-linked network enabled the shape and thermal stability of the composite PCMs, effectively preventing leakage problems. Simultaneously, the composite PCMs possessed a high heat storage capacity of 169.03 J/g, which exhibited excellent thermal reliability and cycling stability for experiencing 200 thermal cycles at 80 °C, revealing effective temperature regulation performance. Furthermore, the interconnected framework also fulfilled the composite PCMs with an improved thermal conductivity, which was even 48.86% higher than that of pure PCMs. In addition, the TBC/CNC composite PCMs exhibited not only a rapid and reversible thermochromic response but also good mechanical stability with a high compressive modulus of 6.1597 MPa. This work provides a sustainable material design strategy for expanding the applications of PCMs.