Confinement effect on enthalpy of fusion and melting point of organic phase change materials in cylindrical nanospace of mesoporous silica and carbon

Organic phase change materials (PCMs) were successfully confined into mesopores of host materials independently via vapor transportation to precisely investigate the changes in the enthalpy of fusion and the melting point of such confined PCMs under various conditions. Paraffins, fatty acids, and fatty alcohols with long hydrocarbon chains were employed as guest PCMs. Mesoporous silica SBA-15s and soft-templated mesoporous carbons with cylindrical mesopores were employed as host materials of the guest PCMs. It was elucidated that mesopore diameter, functional groups of both PCMs and functional groups of host materials result in significant changes in the enthalpy of fusion and the melting point of confined PCMs. Furthermore, it was concluded that the host materials with mesopores of diameter 10-20 nm and minimum interaction between PCM molecules and the functional group on the wall of mesopores of host materials are required to obtain an enthalpy of fusion of confined PCMs as much as 50% of that in its bulk phase.