Studies of hydrogels and concentrated aqueous ionic solutions by optical Kerr effect
Abstract/Contents
- Abstract
- A comprehensive understanding of water and its properties is vital for many Earth processes, ranging from the vast scales of climate and geology to the molecular impact on life. It is essential to have a deep knowledge of water to address critical issues such as climate change, energy, and medicine. This research is specifically focused on two main questions: how water impacts polymer structure and how salt affects water properties. All the data were collected using optical heterodyne-detected optical Kerr effect (OHD-OKE). The ultrafast dynamics of acrylamide monomers (AAm), polyacrylamide (PAAm), and polyacrylamide hydrogels (PAAm-HG) in water were investigated using OHD-OKE. In this study, the systems' dynamics slowed with increasing concentration. AAm samples exhibited tetra-exponential decays, mostly following Debye-Stokes-Einstein behavior except at the highest concentration. Low PAAm concentrations displayed a single power law decay, while high PAAm concentrations and all PAAm-HG concentrations exhibited two power laws. PAAm and PAAm-HG displayed nearly identical dynamics at high concentrations, indicating similar chain-chain interactions. The dynamics of concentrated lithium chloride and lithium bromide aqueous solutions were studied at moderate to high concentrations. While pure water decayed biexponentially, LiCl/LiBr-water decays were tetra-exponential at all concentrations. The faster two decays originated from water dynamics, while the slower two decays reflected ion-water network dynamics. The fastest decay was the same as pure water at all concentrations. The second decay matched pure water at lower concentrations but slowed with increasing concentration. The slower dynamic, the third- and fourth-time constants, arose from ion-water complexes and an extended ion-water network at the highest concentrations. Comparisons with simulations enabled the assignment of dynamics to specific ion-water structures. The concentration-dependent bulk viscosity and ion-water network dynamics were directly correlated, providing an atomistic-level understanding of viscosity.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2023; ©2023 |
| Publication date | 2023; 2023 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Van Wyck, Stephen Jedidiah |
|---|---|
| Degree supervisor | Fayer, Michael D |
| Thesis advisor | Fayer, Michael D |
| Thesis advisor | Cui, Bianxiao |
| Thesis advisor | Zare, Richard N |
| Degree committee member | Cui, Bianxiao |
| Degree committee member | Zare, Richard N |
| Associated with | Stanford University, School of Humanities and Sciences |
| Associated with | Stanford University, Department of Chemistry |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Stephen J. Van Wyck. |
|---|---|
| Note | Submitted to the Department of Chemistry. |
| Thesis | Thesis Ph.D. Stanford University 2023. |
| Location | https://purl.stanford.edu/xc632jn4938 |
Access conditions
- Copyright
- © 2023 by Stephen Jedidiah Van Wyck
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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