Comprehensive analysis of polyethylene glycol – lauric acid as a promising phase change material: Spectroscopic, thermal, and quantum insights

Abstract

The increasing need for effective and environmentally sustainable energy storage technologies has delineated phase change materials (PCMs) as prospective candidates for thermal energy storage applications. In this study, we thoroughly analyzed polyethylene glycol (PEG 400) and lauric acid (LA) as promising PCMs by applying spectroscopic study, thermal, and quantum approaches. The thermal stability and chemical compatibility of PEG – LA were investigated using FTIR and Raman spectroscopy, revealing that optimal molecular interactions and structural changes occur at temperatures ranging from −10 °C to 30 °C, especially at higher LA volume fraction (VLA ≥ 60 %), as evidenced by marked blue shifts in the Raman spectra. TGA demonstrated the 2-step degradation of the PEG – LA (6:4), representing good material stability and high thermal conductivity enhancement of 32.24 % due to synergistic interactions among PEG and LA. DSC analysis established a high capacitive energy storage of 181.5 J/g and a phase transition of solid–liquid at room temperature (30–40 °C), which better crystallization properties based on higher LHR and supercooling degree compared with pristine LA. The thermal cycling reliability and FTIR spectra demonstrated the thermal and chemical stability of PEG – LA even after 1000 cycles. Quantum DFT analysis verified the experimental results, exhibiting robust hydrogen bonding interactions that contribute to the thermal stability, phase transition processes, higher energy storage capacity, and reactivity of PEG – LA. These results highlight PEG – LA as a promising and effective PCM for various thermal energy storage applications.