https://scholars.lib.ntu.edu.tw/handle/123456789/61681
標題: | 自洽平均場理論於雙親性嵌段共聚物/溶劑系統之分析及其於奈米材料之應用 SCMF Analysis for The Amphiphilic Block Copolymer/Solvent System and Its Applications on Nanomaterials |
作者: | 張雍 CHANG, YUNG |
關鍵字: | 奈米材料;自洽平均場理論;共聚物;Nanomaterials;Copolymer;SCMF | 公開日期: | 2004 | 摘要: | 近年來,由於雙親性嵌段共聚物特殊之自組裝結構型態受到廣泛的研究及討論,對於奈米結構材料之製備與應用開啟了另一個新的途徑。但要如何精準的控制雙親性嵌段共聚物於材料製備過程中的奈米結構尺寸,仍尚未被完整而清楚地探討。在本研究中,由自洽平均場理論(self-consistent mean-field ; SCMF)出發,建立適當之理論模型來探討雙親性嵌段共聚物/溶劑系統中的特殊結構型態的變化與特定尺寸的控制,以及其應用於聚甲基倍半矽氧烷之奈米孔洞材料的孔洞尺寸分析。 本文第一部份運用自洽平均場理論計算來探討溶劑添加對於雙親性嵌段共聚物以球狀體心立方堆積(bcc)為穩定結構的影響,並分析微結構尺寸的標度性。當溶劑不具選擇性(中性溶劑)時,稀薄近似(dilution approximation)的使用需被檢驗並分析其如何受到溶劑濃度、共聚物雙親性質以及共聚物聚合度的影響。本研究有系統地分析中性溶劑在不同微結構區域的累積對於結構尺寸變化的影響。由理論計算的結果顯示,溶劑於微相分離區域界面的累積越多對於稀薄近似會產生較大的偏差,且其於微結構尺寸在靠近有序-無序轉變的情況下亦會產生較大的偏差。另一方面,本研究亦探討溶劑的選擇性與含量的變化對於球狀體心立方堆積的相區與結構尺寸的影響。增加溶劑的選擇性、A/B鏈段間的不相容性與共聚物的聚合度均會擴大球狀體心立方堆積的穩定相圖區域。由成份分佈的計算結果顯示,當溶劑的選擇性增加時,溶劑分散到親合鏈段的區域且與非親合鏈段開始產生排斥。 本文第二部份使用自洽平均場理論建立一適當的模型來探討並預測嵌段共聚物PS-b-P2VP於聚甲基倍半矽氧烷(MSSQ)材料中所生成的奈米孔洞之尺寸大小,可有助於製備特定尺寸大小的孔洞結構及薄膜特性的控制。由SCMF建立的理論計算模型可成左獄〝 Amphiphilic block copolymers have become new approaches for preparing nanomaterials with accessible self-assembled morphologies. However, the precise control on the length scale of microstructure from amphiphilic block copolymers has not been fully explored. In this thesis, self-consistent mean-field (SCMF) was employed to analyze phase and scale behavior of the amphiphilic block copolymer/solvent systems and its applications on pore morphology analysis of nanoporous methyl silsesquioxane. In the first part of this dissertation, the effects of solvent addition on body- centered cubic (bcc) spheres of block copolymers was investigated by SCMF calculations. For the case of amphiphilic block copolymer/neutral solvent system, the accuracy of the dilution approximation, the scaling behavior of the bcc structural sizes with copolymer volume fraction, the interaction parameter, and degree of copolymerization were analyzed. The study systematically analyzed the effects of neutral solvent accumulation at the interface on the resulting length scales of each segregated domain, such as the A-rich and B-rich phases, as well as the interfacial width for the block copolymer spheres in the bcc array. In particular, it was found that more solvent accumulation at the interfaces resulted in the increase of deviation from the dilution approximation. The solvent accumulation effects strongly affected the scaling behavior of the domain spacing and the matrix domain length when the order-disorder transition was approached. For the case of selective solvent, the influence of solvent selectivity, solvent content on ordered phase window, and the scaling behavior of the bcc structural sizes were examined. The increase of solvent selectivity, incompatibility of A/B segment and molecular weight of copolymer expanded the region of stable ordered SABCC from the results of constructed phase maps. It was found that unfavorable chain expelling occured and solvent partitions preferentially to favorable chain region as increasing the solvent selectivity from the predicted density profiles. In the second part of this dissertation, the prediction of pore size for the nanoporous MSSQ thin films by templating amphiphilic block copolymers, polystyrene-block –poly(2-vinyl pyridine)(PS-b-P2VP), was investigated. The simplified model from SCMF theory provided a successful methodology to demonstrate the effects of the copolymer composition, the MSSQ/porogen interaction, and the porogen loading ratio on the microdomain spacing and pore diameter with the body-centered-cubic sphere phase. For approaching higher pore density and smaller closed pore size in the MSSQ porous thin film, more composition fraction of the prepared PS block (fPS) and appropriate thermal curing temperature as well as smaller |
URI: | http://ntur.lib.ntu.edu.tw//handle/246246/52163 | 其他識別: | en-US |
顯示於: | 化學工程學系 |
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ntu-93-D89524011-1.pdf | 23.53 kB | Adobe PDF | 檢視/開啟 |
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