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Nanoconfined Water and Water-Mediated Ion Transport in Model Lyotropic Liquid Crystals
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| 자료유형 | 학위논문 |
|---|---|
| 서명/저자사항 | Nanoconfined Water and Water-Mediated Ion Transport in Model Lyotropic Liquid Crystals. |
| 개인저자 | Jackson, Grayson L. |
| 단체저자명 | The University of Wisconsin - Madison. Chemistry. |
| 발행사항 | [S.l.]: The University of Wisconsin - Madison., 2018. |
| 발행사항 | Ann Arbor: ProQuest Dissertations & Theses, 2018. |
| 형태사항 | 326 p. |
| 기본자료 저록 | Dissertations Abstracts International 81-02B. Dissertation Abstract International |
| ISBN | 9781085559539 |
| 학위논문주기 | Thesis (Ph.D.)--The University of Wisconsin - Madison, 2018. |
| 일반주기 |
Source: Dissertations Abstracts International, Volume: 81-02, Section: B.
Advisor: Mahanthappa, Mahesh K. |
| 이용제한사항 | This item must not be sold to any third party vendors. |
| 요약 | The ill-defined pore morphologies and connectivities of conventional membrane materials has hampered a clear understanding of the relationship between pore geometry, pore interfacial chemistry, and ultimate membrane performance. A host of empirical studies have suggested that membranes with sub-5 nm pores are ideal for applications in water purification or ion transport. Formed by the aqueous self-assembly of ionic amphiphiles, lyotropic liquid crystal (LLC) network (N) phases are candidate membrane materials by virtue of their percolating, sub-3 nm pores. The well-defined pore structures and interfacial chemical functionalities of LLCs also make them an attractive platform for fundamental studies of water-mediated H+ transport and water dynamics in nanoporous materials. Recent studies have demonstrated that dicarboxylate gemini amphiphiles stabilize N-phase LLCs, yet their utility in practical applications remains untested.In this thesis, we explore amphiphile design criteria for the stabilization of N-phase LLCs and investigate how water dynamics depend on nanopore geometry and interfacial chemistry. We specifically investigate the ability of gemini amphiphiles to serve as "value-added" components that direct the self-assembly of conventional single-tail amphiphiles into N-phase LLCs as a function of gemini loading, molecular structure, and surfactant counterion identity. These studies reveal that the unique molecular conformations adopted by the dicarboxylate gemini amphiphiles enable them to function as highly anisotropic inclusions that drive LLC N-phase formation.We further utilize LLC self-assemblies as a platform to explore the relationship between H+ conductivity and nanopore geometry. Through the rational design and synthesis of a gemini bis(sulfonic acid) amphiphile and a highly branched sulfonic acid amphiphile, we investigate H+ conductivity in LLCs with either convex or concave nanopores, respectively. We observe that proton conductivity is maximized through intermediate-diameter nanopores and is further increased in convex nanopores. In order to understand this surprising result, we investigate confined water dynamics in the convex nanopores of gemini dicarboxylate LLCs using quasielastic neutron scattering (QENS). We find that water diffusion depends most sensitively on pore size or water content, but is also affected by the identity of the surfactant counterion. Subsequent studies of water dynamics in alkylsulfonate LLCs establish that water diffusion is systematically faster in sulfonated nanopores, and that, independent of pore interfacial chemistry, water diffusion is slower in convex nanopores. From these studies emerge new design criteria suggesting that membranes with convex nanopores may function as highly efficient ion transporting and water purification membranes. |
| 일반주제명 | Chemistry. Polymer chemistry. Materials science. |
| 언어 | 영어 |
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