Role and influence of hydrogen bonds in composite phase change materials: A critical review

Hydrogen bonds (H-bonds) in phase change materials (PCMs) had different effects on phase change behavior and heat storage characteristic. This review focused on the latest experimental progress of PCMs with H-bonds and the controversial effect of H-bonds on the phase change behavior and heat storage characteristic. Some scholars believed that the strong restriction brought by the strong H-bonds required a higher temperature to complete phase change process, and the phase change temperature increased. Conversely, others thought that the strong H-bonds would limit the phase change behavior and reduce the phase change temperature. Furthermore, the effect of H-bonds on phase change latent heat was as follows: for PCMs such as sugar alcohols, H-bonds were the source of phase change latent heat. For composite PCMs encapsulated with porous media, H-bonds would hinder the phase change process, resulting in limited latent heat. Type, strength and density of H-bonds would affect the heat storage characteristic. Meanwhile, the H-bonds could improve other properties, such as, encapsulation capability, morphological stability, thermal stability, mechanical properties, etc. This work could provide basis and support for an in-depth understanding of the internal relationship between H-bonds structure and properties regulation of PCMs.