Rational Fabrication of High-Performance and Scalable Opal Crystals for Thermo-Fluidic Applications
Inverse opals have continuously attracted interest as a scalable, ordered porous material capable of enhancing energy, fluid, mass, or ion transport in a wide variety of applications. In particular, in heat transfer applications they have been used as porous coatings for condensers and boilers for i...
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| Format: | Thesis |
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Massachusetts Institute of Technology
2022
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| Online Access: | https://hdl.handle.net/1721.1/138999 http://orcid.org/0000-0002-1890-4863 |
| _version_ | 1811091963325186048 |
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| author | Díaz-Marín, Carlos D. |
| author2 | Wang, Evelyn N. |
| author_facet | Wang, Evelyn N. Díaz-Marín, Carlos D. |
| author_sort | Díaz-Marín, Carlos D. |
| collection | MIT |
| description | Inverse opals have continuously attracted interest as a scalable, ordered porous material capable of enhancing energy, fluid, mass, or ion transport in a wide variety of applications. In particular, in heat transfer applications they have been used as porous coatings for condensers and boilers for increased efficiency in steam power plants and in two-phase thermal management devices with the potential of enabling next-generation electronic devices with high power density. However, several challenges remain with the fabrication of high-performance inverse opals due to limitations and defects of the initial opal template that ultimately prevent these structures from fulfilling their potential.
In this thesis, we first present a review of opal fabrication techniques and their implementation in heat transfer applications. We highlight previous challenges using these methods to achieve highly permeable structures in a simple way and we introduce slope self-assembly as a means to overcome several of these challenges. Despite its potential, we describe how fundamental understanding of this method is lacking, which limits its use with an arbitrary sphere size.
Second, in order to address this limited understanding, we develop a scaling-based model to elucidate the self-assembly process. Our model predicts the existence of two regimes: a gravity-driven flow regime for small colloidal particles, where the process is dominated by fluid flow, and a capillary-driven regime for large colloidal particles where the capillary forces between spheres dominate the process. With this model, we are able to predict and control the opal coverage on the substrate as a function of the experimental parameters.
Third, we perform experimental validation of our model by fabricating opal samples under different combinations of sphere sizes, colloidal concentrations, slope angles, and temperatures and analyze these samples with a custom image processing code. Our results confirm the validity of our model: for spheres smaller than 2 μm, the process is dominated by gravity-driven flow and the coverage can be controlled by changing the temperature, angle of inclination of the substrate, colloidal concentration, and sphere diameter, while for spheres larger than 10 μm the process is dominated by the capillary-driven flow and it can be controlled by changing the initial volume of solution, the concentration, and the sphere size.
Finally, we use the insights generated by our model to rationally fabricate millimeter-scale samples with monolayer coverage with sphere sizes between 500 nm to 10 μm, which is 10 times larger than the sphere size possible with the vertical deposition method, which has been commonly used for thermo-fluidic applications. Even larger, centimeter-scale samples are possible with some sphere stacking or small uncovered areas. Additionally, we show how this method can be used in a copper substrate, showing its applicability in heat transfer applications. Lastly, we highlight some future opportunities based on our work including the fabrication of multi-porous structures and the experimental tuning of the crystallinity of the opals while maintaining large-scale area coverage. |
| first_indexed | 2024-09-23T15:10:43Z |
| format | Thesis |
| id | mit-1721.1/138999 |
| institution | Massachusetts Institute of Technology |
| last_indexed | 2024-09-23T15:10:43Z |
| publishDate | 2022 |
| publisher | Massachusetts Institute of Technology |
| record_format | dspace |
| spelling | mit-1721.1/1389992022-01-15T03:11:21Z Rational Fabrication of High-Performance and Scalable Opal Crystals for Thermo-Fluidic Applications Díaz-Marín, Carlos D. Wang, Evelyn N. Massachusetts Institute of Technology. Department of Mechanical Engineering Inverse opals have continuously attracted interest as a scalable, ordered porous material capable of enhancing energy, fluid, mass, or ion transport in a wide variety of applications. In particular, in heat transfer applications they have been used as porous coatings for condensers and boilers for increased efficiency in steam power plants and in two-phase thermal management devices with the potential of enabling next-generation electronic devices with high power density. However, several challenges remain with the fabrication of high-performance inverse opals due to limitations and defects of the initial opal template that ultimately prevent these structures from fulfilling their potential. In this thesis, we first present a review of opal fabrication techniques and their implementation in heat transfer applications. We highlight previous challenges using these methods to achieve highly permeable structures in a simple way and we introduce slope self-assembly as a means to overcome several of these challenges. Despite its potential, we describe how fundamental understanding of this method is lacking, which limits its use with an arbitrary sphere size. Second, in order to address this limited understanding, we develop a scaling-based model to elucidate the self-assembly process. Our model predicts the existence of two regimes: a gravity-driven flow regime for small colloidal particles, where the process is dominated by fluid flow, and a capillary-driven regime for large colloidal particles where the capillary forces between spheres dominate the process. With this model, we are able to predict and control the opal coverage on the substrate as a function of the experimental parameters. Third, we perform experimental validation of our model by fabricating opal samples under different combinations of sphere sizes, colloidal concentrations, slope angles, and temperatures and analyze these samples with a custom image processing code. Our results confirm the validity of our model: for spheres smaller than 2 μm, the process is dominated by gravity-driven flow and the coverage can be controlled by changing the temperature, angle of inclination of the substrate, colloidal concentration, and sphere diameter, while for spheres larger than 10 μm the process is dominated by the capillary-driven flow and it can be controlled by changing the initial volume of solution, the concentration, and the sphere size. Finally, we use the insights generated by our model to rationally fabricate millimeter-scale samples with monolayer coverage with sphere sizes between 500 nm to 10 μm, which is 10 times larger than the sphere size possible with the vertical deposition method, which has been commonly used for thermo-fluidic applications. Even larger, centimeter-scale samples are possible with some sphere stacking or small uncovered areas. Additionally, we show how this method can be used in a copper substrate, showing its applicability in heat transfer applications. Lastly, we highlight some future opportunities based on our work including the fabrication of multi-porous structures and the experimental tuning of the crystallinity of the opals while maintaining large-scale area coverage. S.M. 2022-01-14T14:43:42Z 2022-01-14T14:43:42Z 2021-06 2021-06-30T15:16:14.266Z Thesis https://hdl.handle.net/1721.1/138999 http://orcid.org/0000-0002-1890-4863 In Copyright - Educational Use Permitted Copyright MIT http://rightsstatements.org/page/InC-EDU/1.0/ application/pdf Massachusetts Institute of Technology |
| spellingShingle | Díaz-Marín, Carlos D. Rational Fabrication of High-Performance and Scalable Opal Crystals for Thermo-Fluidic Applications |
| title | Rational Fabrication of High-Performance and Scalable Opal Crystals for Thermo-Fluidic Applications |
| title_full | Rational Fabrication of High-Performance and Scalable Opal Crystals for Thermo-Fluidic Applications |
| title_fullStr | Rational Fabrication of High-Performance and Scalable Opal Crystals for Thermo-Fluidic Applications |
| title_full_unstemmed | Rational Fabrication of High-Performance and Scalable Opal Crystals for Thermo-Fluidic Applications |
| title_short | Rational Fabrication of High-Performance and Scalable Opal Crystals for Thermo-Fluidic Applications |
| title_sort | rational fabrication of high performance and scalable opal crystals for thermo fluidic applications |
| url | https://hdl.handle.net/1721.1/138999 http://orcid.org/0000-0002-1890-4863 |
| work_keys_str_mv | AT diazmarincarlosd rationalfabricationofhighperformanceandscalableopalcrystalsforthermofluidicapplications |