Ti3C2Tx@PDA-Integrated Polyurethane Phase Change Composites with Superior Solar-Thermal Conversion Efficiency and Improved Thermal Conductivity

Organic phase change materials (PCMs) have attracted increasing attention in the solar energy utilization field for their large thermal energy storage density, appropriate phase transition temperature, and excellent chemical stability. However, the liquid leakage defect and poor solar-thermal conversion performance restrict their large-scale application. Herein, novel PCM composites with superior solar-thermal conversion efficiency, excellent form-stability, and improved thermal conductivity were successfully synthesized by introducing a dopamine-decorated MXene (Ti3C2Tx@PDA) into a poly(ethylene glycol) (PEG)-based polyurethane PCM. Ti3C2Tx@PDA, which was covalently bound to polyurethane, acted as a photon capturer and molecular heater and converted solar energy to thermal energy, whereas the PEG-based polyurethane PCM could absorb and store the generated thermal energy through solid-solid phase transition. Sunlight irradiation experiments demonstrated that the solar-thermal conversion and storage efficiency of PCM composites (up to 90.1%) were significantly improved with the introduction of the MXene Ti3C2Tx@PDA Based on differential scanning calorimetry (DSC) analysis, PCM composites exhibited satisfactory phase change enthalpy in the range of 121.9-128.2 J/g. Moreover, the developed PCM composites possessed excellent form-stability, remarkable thermal reversibility, good thermal stability, and improved thermal conductivity. In conclusion, the synthesized PCM composites exhibited tremendous application potential in solar energy utilization field.