The regulation of the thermal conductivity of thermal energy storage materials has become a primary challenge to expand the range of utilization for different application scenarios. In this study, organic-shell microcapsule (paraffin@melamine formaldehyde) was initially prepared by polymerization, followed by the deposition of anatase TiO on the organic-shell microcapsule using atomic layer deposition (ALD) to form organic-inorganic double-shell microcapsule. The effect of the thickness of the TiO shell on the equivalent thermal conductivity of the microcapsules was investigated by utilizing ALD's precise and controllable characteristics for the coating thickness. The obtained double-shell microcapsules indicated a drop in thermal storage capacity, but a substantial boost in thermal stability. Moreover, the thermal conductivity of microcapsules can be tuned in the range between 0.1837 and 0.7529 W m K within 1500 ALD cycle treatment. Furthermore, the parameters of ALD, such as reaction temperature and exposure time, were varied to obtain an amorphous TiO shell, and the impacts of different crystal form of TiO on the heat transfer properties of microcapsules were concluded by comparison. Double-shell microcapsules exhibited superior mechanical properties compared to single-shell structure. The findings can stimulate significant research interest in broadening the applications of thermal storage microcapsules.

中文翻译：

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原子层沉积触发的有机-无机双壳蓄热微胶囊热导率的调控

储热材料导热系数的调控已成为扩大不同应用场景的利用范围的首要挑战。本研究首先通过聚合制备有机壳微胶囊（石蜡@三聚氰胺甲醛），然后利用原子层沉积（ALD）在有机壳微胶囊上沉积锐钛矿型TiO，形成有机-无机双壳微胶囊。利用 ALD 涂层厚度精确可控的特性，研究了 TiO2 壳的厚度对微胶囊等效导热系数的影响。所获得的双壳微胶囊的蓄热能力下降，但热稳定性大幅提高。此外，微胶囊的热导率可以在1500次ALD循环处理内调整在0.1837至0.7529 W·m·K之间。此外，改变ALD的参数，如反应温度和暴露时间，获得非晶态TiO壳，并通过比较得出不同晶型的TiO对微胶囊传热性能的影响。与单壳结构相比，双壳微胶囊表现出优异的机械性能。这些发现可以激发人们对扩大蓄热微胶囊应用的重大研究兴趣。