Covalent organic frameworks (COFs) are a novel class of crystalline materials with regular porosity, high specific surface area, and various linkage chemistries. Conventional chemical syntheses of these materials lead to the formation of bulk powders characterized as polycrystalline aggregates. Synthesizing these materials as colloidal systems is an effective means to prevent aggregation and achieve larger single-crystalline domain sizes. In this thesis, I describe the effect of temperature and transimination catalyst strength on COF particle nucleation and particle growth. Morphology and crystallinity of the COF-300 particles were confirmed using X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The onset of colloidal light scattering, or the Tyndall Effect, was measured using Dynamic Light Scattering (DLS). Reaction temperature affects both the reaction rate and the solubility of the monomeric and oligomeric species. The higher solubility at higher temperatures is hypothesized to delay particle nucleation, or the onset of colloidal light scattering. DLS measurements confirmed these results. However, measurement of particle size using DLS and SEM showed little association between the particle size and reaction temperature. Stronger acids are similarly hypothesized to accelerate the chemical reaction, leading to a shorter induction delay and smaller particles. DLS measurements confirmed this hypothesis on the effect of acid catalyst on the induction delay; stronger acids led to a v shorter induction delay. However, preliminary SEM measurements suggest that stronger acid catalysts create larger COF-300 particles.
| Identifer | oai:union.ndltd.org:CALPOLY/oai:digitalcommons.calpoly.edu:theses-3844 |
| Date | 01 June 2021 |
| Creators | Posson, Brendan |
| Publisher | DigitalCommons@CalPoly |
| Source Sets | California Polytechnic State University |
| Detected Language | English |
| Type | text |
| Format | application/pdf |
| Source | Master's Theses |
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