以耗散粒子動力學模擬雙成分奈米顆粒與雙嵌段高分子複合材料於剪切流場下之形態轉換研究

Dissipative Particle Dynamics Simulations on the Shear-Induced Morphological Transitions of Binary Nanoparticles within Diblock Copolymers Composite

李孟竹(Li, Meng Chu)

指導教授 ： 張榮語

國立清華大學/工學院/化學工程學系/碩士(2015年)

https://doi.org/10.6843/NTHU.2015.00570

摘要

本論文係利用耗散粒子動力學模擬，進行研究雙奈米顆粒於雙嵌高分子複合材料中，親性雙奈米顆粒之體積分率對雙嵌段隨流場之形態轉換與奈米顆粒聚集所造成的效應。研究於對稱型雙嵌段高分子中各別添加親性奈米顆粒，體積分率為0.5%、1%、2%、3%、4%，且不同剪切速率下觀察與統計其高分子形態與奈米顆粒聚集情形。另外將親A的奈米顆粒接枝視為大顆奈米顆粒，觀察其影響。
研究結果發現，其自組裝結構會受到流速、奈米顆粒濃度和奈米顆粒聚集情況影響。隨著流速增加，使嵌段高分子鏈段被拉伸，使層板結構轉變。相較流速，奈米顆粒濃度的增加對高分子鏈段拉伸的影響較小。奈米顆粒濃度的改變主要影響著奈米顆粒的聚集情形，隨著奈米顆粒濃度增加，奈米顆粒聚集程度是上升的。奈米顆粒濃度和聚集程度會共同影響系統的熵值，進而影響系統的結構轉變。
將雙成分奈米顆粒其中親A的奈米顆粒變更為大顆奈米顆粒時，從結構相態觀察，由密度分佈圖大顆奈米顆粒較易集中於A層中間，使得A層的末端距離減小，出現網狀結構。當奈米濃度增加，大顆奈米顆粒易集中於A層中間和彼此吸引，造成聚集程度是上升，而將層板結構破壞，而產生穿孔層板的情形。

關鍵字

耗散粒子動力學 ； 高分子奈米複合材料 ； 自組裝行為 ； 剪切流場 ； 形態結構

並列摘要

In this thesis, the impact of the binary nanoparticle volume fraction and shear-induced diffusion on the morphology transition of binary nanoparticles within symmetric diblock copolymers composite is investigated via the experiments done by dissipative particle dynamics simulation. The morphology of two different size of A-affinity nanoparticle is also analyzed under various condition combinations of the nanoparticle volume fraction and shear rate of those simulation systems.
The results show that the self-assembly of nanoparticle mixtures in polymer matrix is a cooperative assembly that is affected by various factors. The tensile properties of diblock copolymer increase with increasing shear rate activating the morphology transition. On the contrary, the tensile properties of diblock copolymer are not related to the nanoparticle volume fraction, but nanoparticle aggregation. It shows that with increasing nanoparticle volume fraction aggregation increases. These results suggest that both volume fraction and aggregation effect translational entropy which contributes to the morphology transition.
As the size of A-affinity nanoparticle increasing, the larger particles concentrate in the center of the domain which makes the end-to-end distance of A chain segment decrease with net structure. On the other hand, a phase transition from the lamellar to perforated layer (PLs) phase can be obtained by increasing nanoparticle volume fraction .

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