氧化鋁矽奈米管之力學性質探討與海水淡化應用

本研究第一部分以多尺度模擬方法探討氧化鋁矽奈米管的機械性質。藉由分子力學與材料力學中位能項的對應，我們可以將化學鍵當作樑，進而以結構力學的方法來預測奈米管的機械性質。本研究所使用的方法亦可幫助瞭解鍵結強度與奈米管結構對整體機械強度的貢獻比例，並由von Mises應力分布來找出奈米管結構與整體機械強度的關係。　　在大多數文獻中對氧化鋁矽奈米管的研究都是基於沒有缺陷的模型，然而實驗上已經發現實際合成的氧化鋁矽奈米管具有許多不同的缺陷。因此我們接續第一部分的研究，發展了一個缺陷氧化鋁矽奈米管模型，希望藉由其來對氧化鋁矽奈米管缺陷、結構穩定性及機械性質之間的關係做一定量探討。我們模型中使用的奈米管缺陷是根據文獻上的實驗結果。對結構穩定性及機械強度的探討是使用多尺度模擬工具，包含密度泛函理論、分子建模及奈米尺度連續體方法。我們的研究也找出了對氧化鋁矽奈米管穩定性及機械強度最有影響的缺陷結構，希望提供其他研究者一個改進材料的方向。　　本研究第三部分是進行氧化鋁矽奈米管在海水淡化上之效能及應用性的初步評估，包含水的滲透率與阻鹽效果的探討。

關鍵字

Imogolite ；奈米尺度連續體方法；彈性係數；缺陷模型；計算化學

並列摘要

We investigated the mechanical properties of single-walled aluminosilicate nanotubes (AlSiNTs) using a multiscale computational method and then conducted a comparison with single-walled carbon nanotubes (SWCNTs). By comparing the potential energy estimated from molecular and macroscopic material mechanics, we were able to model the chemical bonds as beam elements for the nanoscale continuum modeling. The proposed approach also enabled the creation of hypothetical nanotubes to elucidate the relative contributions of bond strength and nanotube structural topology to overall nanotube mechanical strength. Our results indicated that it is the structural topology rather than bond strength that dominates the mechanical properties of the nanotubes. Finally, we investigated the relationship between the structural topology and the mechanical properties by analyzing the von Mises stress distribution in the nanotubes. Most existing theoretical studies on the mechanical properties of AlSiNTs are based on defect-free models, despite the fact that experiment results have revealed a variety of defects in AlSiNTs. Herein we developed a method for the modeling of defective AlSiNTs to enable the quantitative investigation of relationships among defect structures, structural stability, and mechanical properties of AlSiNTs. The defect structures dealt with in the proposed models are based on experimental findings. Our assessment of the stability and mechanical strength of nanotubes is based on multiscale computational tools, including density functional theory, molecular modeling, and nanoscale continuum modeling. Our study also identified the defect structure with the most pronounced impact on the stability and mechanical properties of AlSiNTs. In the last part of the study, we investigated the performance and applicability of aluminosilicate nanotube membrane, including water permeability and salt rejection for AlSiNTs with various sizes.

並列關鍵字

Imogolite ； Nanoscale continuum modeling ； Elastic modulus ； Defective model ； Computational chemistry

參考文獻

49 Kang, D. Y., Tong, H. M., Zang, J., Choudhury, R. P., Sholl, D. S., Beckham, H. W., Jones, C. W. & Nair, S. Single-Walled Aluminosilicate Nanotube/Poly(vinyl alcohol) Nanocomposite Membranes. ACS Appl. Mater. Interfaces 4, 965-976 (2012).

18 Ozden, S., Ge, L. H., Narayanan, T. N., Hart, A. H. C., Yang, H., Sridhar, S., Vajtai, R. & Ajayan, P. M. Anisotropically Functionalized Carbon Nanotube Array Based Hygroscopic Scaffolds. ACS Appl. Mater. Interfaces 6, 10608-10613 (2014).

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國際替代計量

氧化鋁矽奈米管之力學性質探討與海水淡化應用

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