以耗散粒子動力學模擬奈米顆粒與雙嵌段共聚物複合材料於剪切流場下之形態轉換研究

Dissipative Particle Dynamics Simulation on the Shear-Induced Morphology Transitions of Nanoparticles within Diblock Copolymers Composites

周華展(Hua-Jan Chou)

指導教授 ： 張榮語

國立清華大學/工學院/化學工程學系/碩士(2013年)

摘要

本論文係利用耗散粒子動力學模擬，進行研究奈米顆粒於雙嵌段共聚物複合材料中，顆粒之體積分率與親和性對雙嵌段共聚物隨流場之形態轉換與黏度所造成的效應。研究使用親A嵌段共聚物奈米顆粒與無親性奈米顆粒兩種系統，分別在奈米顆粒體積分率為5%、10%、20%、30%、40%，且不同剪切速率下觀察與統計其高分子形態與黏度之數據。研究結果有二個方向。
一、形態結構
在高分子結構上，親A高分子奈米顆粒系統擁有比較多的形態結構，因為加入親A性奈米顆粒相當於增加A domain的效應，其顆粒會幫助雙嵌段共聚物自組裝結構進行有序-有序相轉換。而無親性奈米顆粒則不會產生有序相轉換的現象，但其顆粒會聚集在高分子層板界面之間降低高分子界面張力而使剪切稀化現象提早發生，又當顆粒濃度高至40%時，顆粒會呈現單層板狀結構橫斷高分子層板。
二、黏度數據
親A性奈米顆粒系統在高濃度下(≥30%)會是六角柱狀結構，其結構不會有剪切稀化現象發生，黏度較穩定不隨流場大小改變而改變，因此可以控制顆粒濃度而決定是否要有剪切稀化的發生。無親性奈米顆粒系統則會因為高分子界面張力降低，而提早發生剪切稀化的現象，且黏度相較於親A性系統都較低，又當奈米顆粒呈現單層板狀時會擁有此次研究最低的黏度。

關鍵字

耗散粒子動力學 ； 共聚物奈米複合材料 ； 自組裝 ； 形態結構 ； 剪切稀化

並列摘要

In this thesis, the impact of the volume fraction and affinity of nanoparticles that are in diblock copolymer composites, on the morphology transition and viscosity of diblock copolymers is investigated via the experiments done by dissipative particle dynamics simulation. The morphology and viscosity of A-affinity system and non-affinity system are analyzed under various condition combinations of the nanoparticle volume fraction and shear rate of those simulation systems.
1. For the morphology
The A-affinity system shows more structure types than the non-affinity on copolymer morphology. Because with the appearance of A-affinity nanoparticle, the effect of A domain can increase to activate the order-order transition of the diblock copolymer morphology, While non-affinity nanoparticle cannot activate the order-order transition. Nevertheless, the particles of non-affinity nanoparticle will congregate in copolymer lamellar to reduce interfacial tension of copolymer lamellar to stimulate the phenomenon of shear thinning. Besides, when the non-affinity particle concentration increases to 40%, a single-lamellar structure is formed by the particles to cut off the copolymer lamellar.
2. For the viscosity
A-affinity system is formed as hexagonal cylinder structure when the concentration is larger than 30%. The viscosity is stable and not changed as shear flow varying. Therefore, the occurrence of shear thinning can be controlled by varying the concentration of particles. On the other hand, in non-affinity system, the phenomenon of shear thinning can occur earlier due to decreased interfacial tension of copolymer. Because of decreased interfacial tension of copolymer, the viscosity is lower than in A-affinity system. The lowest viscosity is observed in this study when the nanoparticles are formed as a single-lamellar structure.

並列關鍵字

Dissipative particle dynamics ； Copolymer Nanocomposites ； Self-Assembly ； Morphology ； Shear Thinning

參考文獻

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