Preparation and characterization of novel MicroPCMs (microencapsulated phase-change materials) with hybrid shells via the polymerization of two alkoxy silanes

MicroPCMs (microencapsulated phase-change materials) were successfully synthesized using MPS (3-(trimethoxysilyl) propyl methacrylate) and VTMS (vinyltrimethoxysilane) as raw materials for hybrid shells, and n-octadecane as core materials. DSC (differential scanning calorimeter) results show that two types of crystals form in core materials of all MicroPCMs during crystallization. The weight ratio of MPS–VTMS, and pH values play significant roles on the performance of final product: n-Octadecane content of MicroPCMs increases from 58.7 wt.% to 76.0 wt.% and their thermal degradation temperature (2 wt.% weight loss) increases from 182.6 °C to 188.9 °C with the weight ratio of MPS–VTMS decreasing from 8:0 to 2:6 in neutral synthesis systems. However, the encapsulation of n-octadecane failed when only using VTMS as hybrid shell precursor; When the weight ratio of MPS–VTMS is fixed to 2:6, the encapsulation efficiency decreases in acidic or basic synthesis systems. The optimized final product, i.e., MicroPCMs obtained with the weight ratio of MPS–VTMS equaling to 2:6 in neutral conditions, display a best thermal properties with highest melting and crystallization latent heat of 166.74 J g−1 and 169.35 J g−1, and the n-octadecane content decreases only by 7.0 wt.% and 10.8 wt.% after thermal treatment and thermal cycling test, respectively. •MicroPCMs containing n-octadecane as core material were successfully synthesized.•MPS and VTMS were used as raw materials for hybrid shells.•Effect of the weight ratio of MPS–VTMS and pH values were investigated.