Self-Assembly Synthesis of Microencapsulated n-Eicosane Phase-Change Materials with Crystalline-Phase-Controllable Calcium Carbonate Shell

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• 作者：Shiyu Yu ; Xiaodong Wang ; Dezhen Wu
• 刊名：Energy & Fuels
• 出版年：2014
• 出版时间：May 15, 2014
• 年：2014
• 卷：28
• 期：5
• 页码：3519-3529
• 全文大小：661K
• 年卷期：v.28,no.5(May 15, 2014)
• ISSN：1520-5029

文摘

Novel microencapsulated phase-change materials based on an n-eicosane core and calcium carbonate (CaCO₃) wall have been synthesized through a self-assembly method. The resultant microcapsules presented rhombohedral and spherical morphologies when the synthesis was performed at different concentrations of surfactant. These two types of the n-eicosane microcapsules also exhibited a well-defined core鈥搒hell structure. X-ray diffraction patterns and Fourier transform infrared spectra confirmed that the rhombohedral microcapsules achieved a calcite CaCO₃ shell, whereas the shell of spherical microcapsules were composed of the vaterite CaCO₃. The crystalline phase of the CaCO₃ shell could be controlled by the concentration of surfactant, sodium dodecylbenzenesulfonate, and a crystalline transition from calcite to vaterite occurred when the synthesis was carried out at the surfactant concentration of 3.0 mmol/L. The investigation of phase-change behaviors demonstrated that the encapsulation of n-eicosane enhanced its crystallinity in the 伪-form and thus led to an increase in crystallization temperature. The spherical microcapsules also exhibited higher encapsulation efficiency and energy-storage efficiency than the rhombohedral ones. The thermal conductivity of the n-eicosane microcapsules was significantly enhanced due to the fabrication of a highly thermally conductive CaCO₃ shell, and accordingly, the supercooling of n-eicosane was suppressed. Considering the easy availability and low cost of CaCO₃, this synthetic technology is worthy extending to the encapsulation of other PCMs with a CaCO₃ shell, and it also exhibits a good prospect in the industrial manufacture of microencapsulated PCMs with inorganic shells.