耗散粒子動力學模擬奈米棒狀顆粒與雙嵌段共聚物共混於剪切流場下之相態變化

Shear-Induced Microphase Transition of Nanorod/Diblock Copolymer Blends via Dissipative Particle Dynamics Simulations

羅予祥(Yu-Hsiang Lo)

指導教授 ： 張榮語

國立清華大學/工學院/化學工程學系/碩士(2012年)

https://doi.org/10.6843/NTHU.2012.00183

摘要

本論文透過耗散粒子動力學方法，模擬奈米棒狀顆粒與雙嵌段共聚物共混系統的相態變化，分析該系統在剪切流場下的微相分離結構以及排向性轉換的機制。同時藉由改變奈米棒狀顆粒對雙嵌段共聚物的親和性，包括雙親性Janus棒狀顆粒、親A嵌段性之棒狀顆粒和無親性之棒狀顆粒，探討並比較不同親和性奈米顆粒對系統結構排向性轉換和流變性質如黏度的影響。
研究結果發現，共混系統受剪切流場誘導，依流場強度分別具有橫斷、平行和垂直三種排向性的層板狀微相結構，不同親和性奈米顆粒會使共混系統延遲或提早發生剪切稀化(shear thinning)現象。此外，由於雙親性Janus棒狀顆粒傾向垂直處於微相分離介面中，能夠同時吸引兩端嵌段分子，所統計出的剪切黏度大於其他親和性奈米顆粒。因此，本論文模擬透過添加奈米顆粒以及剪切流場的誘導，提升材料的加工或機械性質，有助於未來高分子奈米複合材料的應用與研究。

關鍵字

耗散粒子動力學 ； Janus奈米顆粒 ； 剪切流場 ； 雙嵌段共聚物 ； 高分子共混

並列摘要

The shear-induced microphase separation and orientational transitions of diblock copolymer/nanorod blends subjected to steady shear flow, are modeled and simulated via Dissipative Particle Dynamics method. We have tailored the affinity between nanorods and diblock copolymer, and investigated three types of nanocomposites which are containing amphiphilic Janus nanorods, A-affinity nanorods and non-affinity nanorods, respectively. The aim of our present study is to understand that how these different affinity of nanorods affect the orientational transitions of nanocomposites and rheological properties.
The results show that the shear field can be used to induce lamellar phase orientational transitions, such as transverse alignment at zero shear, parallel alignment at low shear rate and perpendicular alignment at high shear rate. The presence of nanorods delays or advances the shear-thinning phenomenon. Especially, since amphiphilic Janus nanorods tend to anchor at the interface of microphase separation, it can attract both blocks of diblock copolymer, therefore increase the viscosity of nanocomposites. Our simulations provide a possible approach to enhance the mechanical and processing properties by applying shear field and adding nanorods, that might help us study further the application of nanocomposites in the future.

並列關鍵字

Dissipative Particle Dynamics ； Janus Nano-particle ； Shear Field ； Diblock Copolymer

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