| Title: |
Generation and Rearrangement of Thioethers for Self-Reinforcing Thermosets and Semi-crystalline Thermoplastic Photopolymers |
| Authors: |
Commisso, Alex |
| Contributors: |
Scott, Timothy; Thurber, Greg Michael; Love, Brian J; Ziff, Robert M |
| Publication Year: |
2023 |
| Collection: |
University of Michigan: Deep Blue |
| Subject Terms: |
Thioether; 3D Printing; Stereolithography; Chemical Engineering; Engineering |
| Description: |
In an effort toward long-term sustainability of plastics, the development of robust polymeric materials with longer lifespans is required. The life cycle of polymeric materials can be expanded by programming polymers with chemical functionalities that afford recyclability or the ability to self-heal and self-reinforce. The versatile nature of thioether chemistry enables facile coupling and rearrangement of covalent bonds due to the reactivity of thiolate anions and thiyl radicals. In this thesis, I will detail two approaches using the versatile thioether chemistry to improve sustainability of polymers: the design of stimuli-responsive self-reinforcing thiol-ene thermosets and the development of recyclable thermoplastic cyclic allylic sulfide resins for stereolithographic additive manufacturing. To produce sustainable polymers that can respond to their environment, two-stage self-reinforcing films incorporating hexaarylbimidazole (HABI) as a mechanophore were investigated. Using orthogonal thiol-ene chemistries, we first generated thioethers through selective polymerization of the thiol/acrylate using nucleophilic thiol-Michael addition. Then, the network-bound HABI was activated to initiate the in situ thiol/allyl radical thiol-ene addition to yield cross-linking via locally generated thioethers. This two-stage network was demonstrated first using light as a stimulus with HABI acting as a thiol-ene photoinitiator. Then demonstrated the mechanically labile nature of HABI for use as a mechanophore in the two-stage polymer. The modification of monomer types and stoichiometric ratios affords almost limitless possibilities for the properties of the first and second stage polymer which can be tailored to a wide variety of applications. Facile generation of thioethers is possible through thiol-ene chemistry but thioethers also possess the ability to be rearranged using addition-fragmentation chain transfer in allyl sulfide functionalities. Here, we evaluated cyclic allylic sulfide (CAS) monomers in thermoplastic ... |
| Document Type: |
thesis |
| File Description: |
application/pdf |
| Language: |
English |
| Relation: |
https://hdl.handle.net/2027.42/176625; https://dx.doi.org/10.7302/7474 |
| DOI: |
10.7302/7474 |
| Availability: |
https://hdl.handle.net/2027.42/176625; https://doi.org/10.7302/7474 |
| Accession Number: |
edsbas.6813F8DA |
| Database: |
BASE |