Novel PEG[sub.6000]–Silica-MWCNTs Shape-Stabilized Composite Phase-Change Materials for Thermal-Energy Storage

• Published in: Polymers 2023-07, Vol.15 (14)
• Main Authors: Nistor, Cristina Lavinia, Gifu, Ioana Catalina, Anghel, Elena Maria, Ianchis, Raluca, Cirstea, Cristiana-Diana, Nicolae, Cristian Andi, Gabor, Augusta Raluca, Atkinson, Irina, Petcu, Cristian
• Format: Article
• Language: English
• Subjects: Force and energy; Heat storage; Silica
• ISSN: 2073-4360; 2073-4360
• DOI: 10.3390/polym15143022

This paper describes the preparation of new PEG[sub.6000]–silica-MWCNTs composites as shape-stabilized phase change materials (ssPCMs) for application in latent heat storage. An innovative method was employed to obtain the new organic–inorganic hybrid materials, in which both a part of the PEG chains, used as the phase change material, and a part of the hydroxyl functionalized multiwall carbon nanotubes (MWCNTs-OH), used as thermo-conductive fillers, were covalently connected by newly formed urethane bonds to the in-situ-generated silica matrix. The study’s main aim was to investigate the optimal amount of PEG[sub.6000] that can be added to the fixed sol–gel reaction mixture so that no leakage of PEG occurs after repeated heating–cooling cycles. The findings show that the optimum PEG[sub.6000]/NCOTEOS molar ratio was 2/1 (~91.5% PEG[sub.6000]), because both the connected and free PEG chains interacted strongly with the in-situ-generated silica matrix to form a shape-stabilized material while preserving high phase-transition enthalpies (~153 J/G). Morphological and structural findings obtained by SEM, X-ray and Raman techniques indicated a distribution of the silica component in the amorphous phase (~27% for the optimum composition) located among the crystalline lamellae built by the folded chains of the PEG component. This composite maintained good chemical stability after a 450-cycle thermal test and had a good storage efficiency (~84%).