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/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 mesoporous silica (MS) with trimethylchlorosilane. Fourier-transformed infrared spectroscopy (FTIR), N2 adsorption-desorption isotherm, and thermogravimetric analysis (TGA) confirmed successful methylation of MS. 1-Octadecanol (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 of OD/MS to 85.6 J/g of 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.