以膠體液滴乾燥法製備自組成結構 及相關展透現象之研究

The percolation of self-assembly structures formed by colloidal droplet evaporation

林子民(Zih-Min Lin)

指導教授 ： 許經夌

中原大學/理學院/應用物理研究所/碩士(2009年)

https://doi.org/10.6840/CYCU.2009.00763

摘要

本實驗利用聚苯乙烯膠體溶液(Polystyrene colloidal solution)的自組成(self-assembly)方式，使粒子在基板上產生不同的圖案(pattern)
，而在液滴乾燥(droplet evaporation)過程中會因為coffee-ring
、Marogoni effect、random pinning等效應的影響使粒子在基板上的排列發生改變；而在理論部份，則採用蒙地卡羅法(Monte Carlo method)來模擬粒子的自組成行為，經由統計後可知，覆蓋率在20~30%時會有展透(percolation)的機率產生，此模擬結果和實驗上所觀察到的情形相符；但在光學顯微鏡的動態觀察中，可看出聚苯乙烯粒子在液滴乾燥過程中會固定(pinning)在基板上，此現象是造成粒子最後產生的圖案和模擬所得到的圖形結果不同的主要原因；另一方面，將金屬奈米粒子膠體溶液滴在電極上，並以同樣的方法製備出奈米網路結構，再利用原子力顯微鏡(Atom Force Microscope，AFM)觀察樣品的表面形貌，可看出樣品呈無序堆疊(disordered aggregation)的多層膜結構，而此結果造成在電性量測上，無法看出有明顯的轉變(transition)產生。

關鍵字

自組成 ； 馬倫哥尼效應 ； 展透 ； 咖啡環 ； 蒙地卡羅法

並列摘要

In our experiments various self-assembled particle film patterns on substrates were fabricated by using polystyrene colloidal droplet evaporation. The aggregation patterns are affected by “coffee-ring”, “Marogoni effect”, and “random pinning” phenomena during the droplet evaporation. We simulated the particle self-assembly behaviors by a lattice gas model with the Monte Carlo method. According to the results of the simulation, we found that the percolation may occur when the particle coverage is between 20% and 30%. These simulated results correspond with our experimental observations. However, our real-time optical microscope observation showed that the polystyrene particles would be pinning randomly on the substrates during the droplet evaporation. It caused different experimental patterns compared with the simulate results. Furthermore, we made self-assembly nanonetwork structures by colloidal metal nanoparticles. Nanostructure analysis of the atomic force microscope (AFM) showed that the nanoparticles aggregated to disordered multilayer structures. Hence, the percolation transition of electrical resistivity was difficult to be observed.

並列關鍵字

Marogoni effect ； self-assembly ； coffee-ring ； Monte Carlo method ； percolation

參考文獻

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