Spontaneous formation of fractal structures on triglyceride surfaces with reference to their super water-repellent properties
Spontaneous formation of fractal structures on triglyceride surfaces with reference to their super water-repellent properties
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DOI：
10.1021/jp065589o
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发表时间：
2007-01-25
影响因子：
3.3
通讯作者：
Tsujii, Kaoru
中科院分区：
文献类型：
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作者：
Fang, Wenjun;Mayama, Hiroyuki;Tsujii, Kaoru
烷基乙烯酮二聚体（AKD）是一种蜡，它能自发形成分形表面，并显示出超强的拒水性。在甘油三酯的这项工作中也发现了这种防水和分形表面的形成。由于这些蜡的晶体相变进行了很好的研究，我们研究了它们的分形表面的形成，通过接触角测量，差示扫描量热法（DSC），和X射线衍射（XRD）。从随时间变化的接触角测量，它被发现，形成超疏水表面的分形结构自发地发生在甘油三酯表面上，在不同的温度。新固化的甘油三酯表面几乎是透明的，并且它们对水的初始接触角接近110度。在特定温度下孵育一定时间后，表面变得粗糙和浑浊。超疏水表面粗糙度较高，呈分形结构，维数约为。2.2通过盒计数法从扫描电子显微镜（SEM）图像计算。DSC和XRD测量清楚地观察到甘油三酯熔体凝固后从亚稳态到稳定的结晶相的转变。这种相变和晶体生长导致了分形晶体结构和超拒水性。确保初始样品固化到亚稳态并在合适的温度下固化表面是成功制备分形甘油三酯表面的关键因素。
Alkylketene dimer (AKD), a kind of wax, has been known to form fractal surfaces spontaneously and show super water-repellency. Such formation of water-repellent and fractal surfaces was also found in this work for triglycerides. Since the crystal phase transitions of these waxes were well studied, we studied the formation of their fractal surfaces through contact angle measurements, differential scanning calorimetry (DSC), and X-ray diffraction (XRD). From time-dependent contact angle measurements, it was found that the formation of super water-repellent surfaces with fractal structures occurred spontaneously also on the triglyceride surfaces at different temperatures. The freshly solidified triglyceride surfaces were almost transparent, and their initial contact angles of water were close to 110 degrees. The surfaces then became rough and clouded after being incubated for a certain time at a specified temperature. The super water-repellent surfaces were quite rough and showed fractal structures with the dimension of ca. 2.2 calculated from the scanning electron microscopic (SEM) images by the box-counting method. The phase transformation from a metastable state to a stable cystalline one after the solidification from the melt of triglycerides was clearly observed by DSC and XRD measurements. The fractal crystalline structures and the super water-repellency resulted from this phase transformation and the crystal growth. Ensuring the initial sample solidified into the metastable state and curing the surface at an appropriate temperature are key factors for the successful preparation of fractal triglyceride surfaces by the solidification method.