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標題: | 奈米碳管在曲面和氣-液界面上的耗盡及疏水相互作用 Depletion and Hydrophobic Interaction of Carbon Nanotubes on the Curved Surface and Air-Liquid Interface |
作者: | Hsin-Chieh Lee 李欣潔 |
指導教授: | 江宏仁(Hong-Ren Jiang) |
關鍵字: | 耗盡相互作用力,奈米碳管,微膠囊,氣-液界面,疏水作用力,微氣泡,界面活性劑, depletion interaction,carbon nanotube,microcapsule,air-liquid interface,hydrophobic force,microbubble,surfactant, |
出版年 : | 2020 |
學位: | 博士 |
摘要: | 耗盡相互作用是在密集擁擠的大分子溶液中懸浮膠體顆粒之間產生的等效吸引力。在本篇論文中,提出在多壁奈米碳管之間引入耗盡作用力。具有疏水性質的多壁奈米碳管透過化學改質,將無毒且高度水溶性的大分子-聚乙二醇嫁接至表面上,使多壁奈米碳管變得可分散在水溶液中。我們發現通過控制聚乙二醇溶液的濃度,引入可調控的耗盡相互作用力於聚乙二醇嫁接的多壁奈米碳管之間使奈米碳管彼此聚集。由於在凹槽表面上耗盡區的重疊體積較大,因此聚乙二醇嫁接的多壁奈米碳管傾向聚集於在凹槽圖案化的表面。 我們亦在氣-液界面上觀察到多壁奈米碳管聚集的現象,進而針對在氣-液界面處的耗盡聚集進行了研究。本研究使用了聚苯乙烯顆粒當作研究氣-液界面處耗盡作用力。在有大分子溶液的氣-液界面處有觀察到大量聚苯乙烯顆粒的聚集,而顆粒在氣-液界面處的浸入深度會受顆粒的疏水性影響。本研究提出顆粒在氣-液界面處提供的耗盡區的大小取決於顆粒的疏水性。根據實驗結果,低疏水性的顆粒更容易在因耗盡作用力而聚集於氣-液界面處。 奈米碳管為中空管棒狀結構。許多研究指出,棒形奈米顆粒排列的取向受剪切力的方向影響。透過施與溶液剪切力使棒形奈米碳管呈現高度取向。高度取向會使奈米碳管的耗盡區具有較大重疊體積,使奈米碳管之間產生更大的耗盡吸引力。根據實驗結果,奈米碳管通過耗盡相互作用在氣-液界面聚集並通過流動增強奈米碳管的聚集。基於此概念,本研究提出了使用雷射直接進行光學加熱產生氣泡的方法,以創造具有氣-液界面和流動的系統,並產生奈米碳管微膠囊。此種在氣-液界面耗盡聚集的技術為微製造領域中提供一個製作微膠囊的方法。 另外,本研究也探討了奈米碳管與氣-液界面無耗盡作用力的疏水作用力。提出一種通過撞擊裝有乙醇-水溶液(不含界面活性劑)的容器以產生大量氣泡的方法。疏水性奈米碳管和親水性羧化奈米碳管可以通過疏水性奈米碳管與上升的微氣泡的附著過程而快速分離。本研究提出在沒有表面活性劑的情況下產生的微泡具有疏水性表面,並且微泡增強了乙醇溶液中的疏水物質分離的機制。根據實驗結果,使用不含界面活性劑溶液產生的微氣泡可以在短時間內實現疏水性奈米碳管的高效回收。這為根據表面性質不同而分離材料提供了一種的方法。 本篇論文中,成功地在奈米碳管之間引入了耗盡力,並進一步研究了奈米碳管在流動系統中與氣-液界面處的耗盡相互作用。根據實驗結果,奈米碳管通過耗盡相互作用而聚集在曲面和氣-液界面上。根據本研究的結果,奈米碳管可通過耗盡作用力應用於小物件的組裝及在表面上形成有序的微陣列。 Depletion interaction is an attraction generated between colloidal particles in a dense solution of macromolecules. In this thesis, the introduction of the depletion force between multi-walled carrbon nanotubes (MWCNT) is proposed. The hydrophobic MWCNTs are chemically modified to graft non-toxic and highly water-soluble macromolecule, polyethylene glycol (PEG), onto the surface. Thus, PEG-CNTs become dispersible in an aqueous solution. By controlling the concentration of the PEG solution, the tunable depletion interaction is introduced between the PEG-CNTs to aggregate with each other. PEG-CNTs tend to aggregate on the patterned surface by depletion interaction because of the larger overlapping volume of depletion zones that occur on the grooved surface. The aggregation of PEG-CNTs at the air-liquid interface is observed, and the depletion aggregation at the air-liquid interface is studied. Polystyrene (PS) particles are used to study depletion aggregation at the air-liquid interface. In the presence of macromolecules, large aggregations of PS particles are observed at the air-liquid interface of the solution. Since the immersion depth of the particles at the air-liquid interface is affected by the hydrophobicity of the particles, the size of the depletion zone provided by the particles at the air-liquid interface is proposed depending on the hydrophobicity of the particles. The concept that particles with low hydrophobicity at the air-liquid interface occurs a larger overlapping volume of depletion zones is proposed. The results show that particles with low hydrophobicity are more likely to aggregate at the air-liquid interface. In terms of structure, CNT is a rod-like structure. Many studies have pointed out that the orientation of the arrangement of rod-shaped nanoparticles is dominated by the direction of shear force. By applying the shearing force to the solution, the rod-shaped CNTs show a high degree of orientation. The high degree of orientation causes the CNTs with larger overlapping volumes of the depletion zone, thereby creating a greater depletion attraction between CNTs. According to the experimental results, CNTs aggregate at the air-liquid interface by depletion interaction, and flow enhances the aggregation of CNTs. Based on these concepts, a method of generating bubbles by direct optical heating using a laser is proposed to create a system with the air-liquid interface and flow to generate CNTs microcapsules by depletion interaction. This method of depletion aggregation on the air-liquid interface provides a method for fabricating microcapsules in the field of microfabrication. The hydrophobic interaction between the CNTs and the air-liquid interface without depletion interaction is also investigated. A method of generating a large number of microbubbles by impacting a container containing an ethanol-water solution (without surfactant) is proposed. Hydrophobic CNTs and hydrophilic carboxylated CNTs (aCNTs) can be quickly separated by the attachment process of hydrophobic CNTs and rising microbubbles. The mechanism that the microbubbles generated in the absence of surfactants have a hydrophobic surface and the microbubbles enhance the separation of hydrophobic material in the ethanol solution is proposed. The results show that the use of surfactant-free microbubbles can efficiently recover hydrophobic CNTs in a short time. This provides a potential method for separating different materials based on their surface properties. In this thesis, the depletion force is successfully introduced between CNTs, and the depletion interaction of CNTs in a flow system and the depletion interaction at air-liquid interfaces are further studied. It is demonstrated that CNTs aggregate on curved surfaces and air-liquid interfaces by the depletion interaction. According to the results of this study, CNTs can be used to assemble small components and form ordered microarrays on the surface by depletion interaction. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/18888 |
DOI: | 10.6342/NTU202003936 |
全文授權: | 未授權 |
顯示於系所單位: | 應用力學研究所 |
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