Methylated mesoporous silica loaded with 1-octadecanol as a new shape-stabilized phase change material for enhanced thermal energy storage efficiency

Here, a 1-octadecanol (OD)/methylated mesoporous silica (OD/M-MS) shape-stabilized phase-change material (SSPCM) was prepared with enhanced thermal energy storage. The M-MS was synthesized by methylation of low-cost MS with trimethylchlorosilane. Fourier-transformed infrared spectroscopy (FTIR), N2 adsorption-desorption isotherm, and thermogravimetric analysis confirmed successful methylation of MS. OD was then impregnated into the pores of MS and M-MS to form OD/MS and OD/M-MS SSPCMs, and their thermal properties were thoroughly characterized and compared. FTIR result of OD/MS revealed interfacial hydrogen bond (H-bond) interactions between the hydroxyl group (-OH) on the OD molecules and silanol groups (Si-OH) on the MS surface. These interactions prevented the free movement and ordered arrangement of OD molecules for crystallization, thus declining the heat storage capacity. By methylating the MS surface, the H-bond interactions were suppressed and the OD/M-MS could recover the thermal performance. The heat storage capacity increased by 96.8% from 43.5 J g-1of OD/MS to 85.6 J g-1of OD/M-MS. Moreover, a test of 400 accelerated thermal cycles proved good thermal reliability for OD/M-MS SSPCM. This work provides an effective strategy to achieve OD/M-MS SSPCM with low cost and high thermal performance, promising for large-scale thermal energy storage applications.