固液介面的研究是尋找分子在介面運動的束縛機制或是疏水機制的關鍵，但現階段實驗的探測儀器在尺度上尚無法滿足這個需求，造成現階段大部份的文獻皆是以微米尺度或是近奈米尺度的表面粗糙來進行說明，無法解釋液滴分子接觸固體表面但沒有在微米或是奈米尺度中沿著表面擴散的現象。為了進一步瞭解介面內部分子的運動機制，我們使用分子動力學模擬(molecular dynamic simulation)來了解分子在奈米尺度下的運動行為以及表面奈米粗糙結構的影響。本實驗以分子動力學模擬三種不同官能基碳鏈長度的三酸甘油酯(Triacylglycerides，簡稱TAGs)的運動行為，其分別為Tributyrin、Trioctanoin與Tripalmitin，三者具有官能基碳鏈長度的差異。我們使用了NERD的力場來進行TAG分子團的平衡，並將TAG液滴放置於平面鑽石基板與島狀鑽石基板進行吸附現象觀察。我們發現官能基碳鏈長度與溫度會影響TAG分子群體的運動侷限性，同時也形成獨特的排列形態。同時，我們進行了TAG液滴吸附於平面與島狀鑽石基板的模擬計算。我們發現液滴的擴散機制會受到二維奈米尺度的表面粗糙圖形影響。這些奈米尺度的介面現象提供了我們描述微觀下液滴接觸角、蓮花效應以及自潔表面機制的能力。

Study of solid-liquid interface are the key to find out molecular constrain mechanism and further hydrophobic mechanism. However, till recently research, we found that most of studies were base on micro-scale/near nano-scale surface roughness pictures to discuss interface phenomena, hardly to know the molecular behavior in the solid-liquid interface and not understand why droplet touch the solid surface without molecule spread along micro-scale/nano-scale surface. To understand molecular behavior in the solid-liquid interface, we use molecular dynamic simulation to reveal nano-scale molecular behavior and the effect of nano-scale surface roughness. In this research, molecular dynamic simulations(MD) was used to study the adsorption behavior of Triacylglycerides(TAGs), in which these TAGs are different in aliphatic chain length on functional group. NERD force field was used to simulate aliphatic chain of TAG molecule. Simulations reveal that aliphatic chain length and temperature influence the intermolecular constrain mechanism which induce different molecule aggregation phenomenon. In addition, adsorption of TAG droplet on flat and patterned diamond surface were also studied. It was found that 2-dimensional patterned nano-scale surface could limit molecule spreading while TAG droplet adsorbed to it. This nano-scale interface effect provides a way to explain droplet contact angle, lotus effect and also self-clean surface mechanism.

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