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Microencapsulation of paraffin with melamine formaldehyde shell (Pn@MF) shows the drawbacks of low thermal conductivity. Hence, we constructed SiO2 shells on Pn@MF phase change microcapsules by interfacial polycondensation to obtain Pn@MF@SiO2 double‐shelled microcapsules. The effect of tetraethoxysilane (TEOS) contents on the performance of Pn@MF@SiO2 was discussed in detail. As the TEOS contents increased, the thermal conductivity of Pn@MF@SiO2 gradually increased, reaching up to 0.376 W m−1 K−1. The Pn@MF@SiO2 have exhibited superior leakage‐proof properties and thermal reliability through double‐shelled protection, and the highest reduction in leakage rate reached 45.06 % compared to Pn@MF microcapsules. The Pn@MF@SiO2‐3 with the lowest enthalpy still exhibit a latent heat storage capacity of more than 176 J/g, which displayed outstanding latent heat storage/release capability and good anti‐permeable property. [ABSTRACT FROM AUTHOR]

A series of paraffin@poly(methyl methacrylate) phase‐change microcapsules (Pn@PMMA) were synthesized by suspension polymerization. The prepared Pn@PMMA had excellent latent heat storage and release properties (ΔHm=183.2 J/g, ΔHc=181.9 J/g), excellent thermal stability and cycle durability of at least 100 cycles. The effects of emulsifier type, cross‐linking agent content and core/shell mass ratio on structure and properties of Pn@PMMA were investigated by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT‐IR) and differential scanning calorimetry (DSC). The morphology of Pn@PMMA exhibited spherical profile with styrene‐maleic anhydride (SMA) as emulsifier and the agglomeration was significantly reduced. The enthalpy of the microcapsules was significantly improved with the addition of crosslinker. The anti‐permeability of Pn@PMMA subsequently further improved with continued increasing amount of cross‐linker. Besides, the enthalpy and anti‐leaking property of the microcapsules progressively reduced with the core/shell mass ratio decreased, while the thermal conductivity gradually increased. Therefore, the results showed that the Pn@PMMA with the enthalpy of 183.2 J/g and the leakage rate of 4.72 %, which displayed a high thermal reliability potential for thermal energy storage and temperature regulation. [ABSTRACT FROM AUTHOR]

A series of paraffin (Pn)@silica (SiO2) microencapsulated phase change materials (MEPCM) were synthesized by sol‐gel process using tetraethyl orthosilicate (TEOS) and silane coupling agent as precursors. The morphology and chemical compositions of Pn@SiO2 microcapsules were characterized by SEM and FT‐IR, and thermal energy storage capacity was tested by DSC. The results showed that the Pn@SiO2 microcapsules modified with 3‐methacryloxypropyltrimethoxysilane (MPS) had a desirable phase transition enthalpy (184.12 J/g). Meanwhile, the contact angle and leakage rate of Pn@SiO2 microcapsules were analyzed, and the data indicated the contact angle of Pn@SiO2 microcapsules was significantly improved and the leakage rate of Pn@SiO2 microcapsules was reduced to different degrees by modification with silane coupling agents. The main reason is that the modification of silane coupling agents improves the wettability of silica on the surface of paraffin wax, which makes the aggregation of silica on the surface of paraffin more efficient. Among them, the Pn@SiO2 microcapsules modified by MPS showed the most significant reduction in leakage rate, which was reduced from 8.38 % to 1.24 %. Pn@SiO2 microcapsules modified by MPS not only showed outstanding latent heat‐storage/release capability with a high capacity but also exhibited good shape stability, high thermal stability and excellent phase‐change reliability and durability. [ABSTRACT FROM AUTHOR]