臺灣博碩士論文加值系統

過去，耗散粒子動力學 (Dissipative Particle Dynamics, DPD)已經很成功地模擬在高分子的相態(Phase)與形態(Morphology)的變化。到目前為止，高分子在剪切流場(Shear Flow)下，還是比較少討論，然而，其原因在於DPD模擬在剪切流場上的應用還沒有被注意。SLLOD演算法已經在傳統的分子動力學模擬(Molecular Dynamics Simulations, MD)上，已經很廣泛地被用來呈現剪切與拉伸流場(Shear and Elongation Flows)，因此，本研究的目的透過耗散粒子動力學模擬，瞭解高分子在剪切流場下，其形態變化，更重要地，對在平衡態下的形態，比較兩者之間的差異性。
本研究使用雙嵌段共聚物(Diblock Copolymer)在不同剪切率(Shear Rate)下計算其黏度(Viscosity)與順向性(Orientation)，發現當剪切率越大其黏度則會遞減，而鏈段則是會趨近於某個方向。在形態變化方面，發現剪切流場可將其形態誘導成水平分層並留有在平衡態下的結構，因此本研究發現可利用剪切流場將形態誘導成某一方向以提高其應用價值。

In the past, Dissipative Particle Dynamics (DPD) has successfully simulated the changes in phase and morphology of polymers. However, the topic of polymer under shear flow has not been studied much up until this point because of the fact that the application of DPD simulation under shear flow has not garnered much attention thus far. Sllod algorithm is used very commonly in the traditional Molecular Dynamics Simulations (MD) to represent shear and elongation flows. Therefore, the objective of this research is to understand the phase change of polymer under shear flow using DPD. And most importantly, compare the differences between the two under equilibrium condition.

In this research, the viscosity and alignment of diblock copolymer are determined under different shear rates. The results are that the viscosity decreases with increasing shear rates and the polymer chains tend to align to a certain direction. For changes in morphology, it is found that shear flow can induce horizontal stratification and maintain equilibrium structure of polymer. Therefore, the application of shear flow can induce the morphology of polymer into a certain alignment which can lead to a wider application of polymer.

摘要 I
Abstract II
目錄 III
圖目錄 VI
表目錄 XIV
第一章 緒論 1
1.1前言 1
1.2 研究動機與目的 5
1.3 雙嵌段共聚物簡介 6
第二章 文獻回顧 10
2.1 耗散粒子動力學模擬文獻回顧 10
2.2 非平衡分子動力學模擬文獻回顧 14
2.3 耗散粒子動力學加入流場模擬文獻回顧 16
第三章 研究方法 23
3.1 耗散粒子動力學基本理論架構 23
3.1.1 耗散粒子動力學的基本假設與模擬流程 24
3.1.2 運動方程式的數值方法 27
3.1.3 週期性邊界與最小鏡像法 28
3.2 耗散粒子動力學作用力場 30
3.2.1 粒子間作用力 30
3.2.2 粒子內作用力 32
3.3 耗散粒子動力學參數定義方法 33
3.4 非平衡分子動力學模擬 38
3.4.1 SLLOD演算法理論架構 39
3.4.2 Lees-Edwards週期性邊界 40
3.4.3 NEMD的計算 42
第四章 模擬系統架構 44
4.1 初步系統架構 44
4.2初步系統驗證與成果 45
4.2.1 DPD系統驗證 45
4.2.2 NEMD系統驗證 46
4.2.3 NEDPD簡單粒子系統之初步成果 49
4.3高分子鏈模擬系統架構 56
4.3.1 高分子鏈段系統之驗證 57
第五章 結果與討論 62
5.1雙嵌段共聚物在剪切流場下流變性質的計算 62
5.1.1 不同shear rate下黏度之計算 62
5.1.2 不同shear rate下順向性之計算 64
5.2雙嵌段共聚物在剪切流場下之形態變化 66
5.2.1 不同shear rate下之形態變化 66
5.2.2 雙嵌段共聚物在平衡態與流場下的形態之比較 82
5.2.3 雙嵌段共聚物在流場下的形態對黏度變化之影響 85
第六章 結論與未來展望 86
參考文獻 88
附錄I 91

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