Organocatalyzed ring opening polymerization and the design of materials for topological trapping
Abstract/Contents
- Abstract
- Ring-opening polymerization (ROP) is a highly useful route to well-defined, high molecular weight polymers. In recent years, strongly nucleophilic neutral bases such as N-heterocyclic carbenes (NHCs) have been shown to catalyze ring opening polymerization with control over the topology of the polymer product. This mechanism has been termed Zwitterionic Ring Opening Polymerization (ZROP). Here, new catalysts and monomers have been explored for these processes. Two types of organocatalysts were developed. A recently reported superbase, cyclopropenimine, was tested for activity with a number of monomers. It was discovered that this catalyst polymerizes lactide not through ZROP, but through anionic ROP initiated by a previously unreported mechanism. It was demonstrated that cyclopropenimines deprotonate lactide to form the corresponding enolate, which serves as the initiator and endgroup for the polymerization. Additionally, an electrophilic co-catalyst for lactide polymerization based on a cationic bis(imidazolium) structure was discovered. Furthermore, a class of cyclic phosphotriesters was synthesized as a substrate for NHC-catalyzed polymerization. Mechanistic studies were consistent with the existing interpretation of ZROP. The topology of the polymer products was found to be highly impacted by slight changes in monomer structure. One of these monomers, 2-isoproxy-1,3,2-dioxophospholane 2-oxide (iPP), yielded high molecular weight cyclic products. To further interrogate the polymer architecture, a crosslinked polyacrylate network was formed in-situ with the poly(iPP). In this way cyclic macromolecules were topologically trapped, preventing their extraction by solvent washing. The gel platform used for this trapping protocol was optimized and this process was explored as a way to sort polymers based on their topology. Finally, the properties of these gels, a unique form of interpenetrating network, were studied.
Description
| Type of resource | text |
|---|---|
| Form | electronic; electronic resource; remote |
| Extent | 1 online resource. |
| Publication date | 2016 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Associated with | Stukenbroeker, Tyler |
|---|---|
| Associated with | Stanford University, Department of Chemistry. |
| Primary advisor | Waymouth, Robert M |
| Thesis advisor | Waymouth, Robert M |
| Thesis advisor | Kool, Eric T |
| Thesis advisor | Wender, Paul A |
| Advisor | Kool, Eric T |
| Advisor | Wender, Paul A |
Subjects
| Genre | Theses |
|---|
Bibliographic information
| Statement of responsibility | Tyler Stukenbroeker. |
|---|---|
| Note | Submitted to the Department of Chemistry. |
| Thesis | Thesis (Ph.D.)--Stanford University, 2016. |
| Location | electronic resource |
Access conditions
- Copyright
- © 2016 by Tyler Scott Stukenbroeker
- License
- This work is licensed under a Creative Commons Attribution Non Commercial 3.0 Unported license (CC BY-NC).
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