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Nanoencapsulation of n-octadecane phase change material with silica shell through interfacial hydrolysis and polycondensation in miniemulsion

Liang, Shuen, Li, Qianbiao, Zhu, Yalin, Chen, Keping, Tian, Chunrong, Wang, Jianhua, Bai, Ruke
Energy 2015 v.93 pp. 1684-1692
Fourier transform infrared spectroscopy, X-ray diffraction, chemical composition, condensation reactions, crystal structure, differential scanning calorimetry, encapsulation, energy, enthalpy, heat, hydrolysis, melting, nanocapsules, nanoemulsions, silica, temperature, thermal conductivity, thermal stability
Nanoencapsulation of n-octadecane phase change material with silica shell was performed through interfacial hydrolysis and polycondensation of tetraethyl orthosilicate in miniemulsion. The chemical composition and crystallinity of the synthesized n-octadecane@SiO2 nanocapsules were characterized by FT-IR spectroscopy and XRD analysis. DSC (differential scanning calorimetry) and TG results demonstrated that the as-prepared nanocapsules have high heat storage capability and good thermal stability. The melting enthalpy and encapsulation ratio of the nanocapsules were as high as 109.5 J g−1 and 51.5%, respectively. Most importantly, n-octadecane@SiO2 nanocapsules with different morphologies and sizes (169–563 nm) have been conveniently obtained via tuning water-to-ethanol ratio in continuous phase of the miniemulsion. With decreasing size of the n-octadecane@SiO2 nanocapsules, the phase change temperatures move to lower values due to Gibbs–Thomson effect. Moreover, the as-prepared nanocapsules possess high thermal conductivity, and can maintain their phase transition properties perfectly after 500 melting–solidifying thermal cycles, making them ideal candidates as thermal energy storage materials.