Dodd, Liam
(2023)
Advancing the Synthetic and Analytical Techniques of Inverse Vulcanisation.
PhD thesis, University of Liverpool.
|
Text
201110520_Nov2023.pdf - Author Accepted Manuscript Download (13MB) | Preview |
Abstract
Inverse vulcanisation is a diverse and versatile polymerisation reaction that reacts elemental sulfur with an olefinic organic compound to generate polymers that can contain large amounts of sulfur by mass. Such reactions usually entail a bulk polymerisation where sulfur is heated beyond its melting point, to temperatures where radical capped sulfur chains form. Upon cooling these chains are unstable, but they can be reacted with carbon – carbon double bonds to create inverse vulcanised polymers: organic units interconnected by chains of sulfur atoms. Normally the organic component would contain multiple olefinic moieties, such that the product is crosslinked, which is generally more stable than the less common examples of linear inverse vulcanised polymers. Inverse vulcanised polymers have a great many applications that make them attractive next generation materials, and many of these properties can be tuned by controlling how much sulfur is used in the synthesis. Even more exciting is the wide library of reactive olefins that are amenable to inverse vulcanisation, each bringing a new product polymer with a different complement of properties. What makes inverse vulcanisation so much more attractive, is that sulfur is an industrial by-product that is produced in vast excesses with supply greatly outweighing demand. Thus, elemental sulfur is remarkably cheap, and since the olefinic reactant can come from a renewable source, inverse vulcanisation can meet the principles of green chemistry. However, inverse vulcanisation suffers from a poorly understood mechanism, little to no regimentation in how syntheses are conducted, and severe issues in the analysis and understanding of the structure of the product polymers, which are issues that the work carried out in contribution to this thesis aimed to remedy with three topics. The first topic examine in this thesis is the catalysis of inverse vulcanisation, which can improve the yield and reaction time of inverse vulcanisation whilst inducing reaction in otherwise unreactive comonomers, and giving product polymers of better properties. By varying the catalyst structure, conclusions were drawn about what makes an effective catalyst and how such catalysts might work. As a follow on from the first, the second topic investigates metal free amine catalysts, which circumvent sustainability concerns of metal containing catalysts as well as metal contamination of the environment. As a natural branch to this project, previously under-investigated alkyne crosslinkers were studied, as well as a dispersion polymerisation method, useful for highly reactive crosslinkers. The final topic is the use of Raman spectroscopic analysis for characterisation of inverse vulcanised polymer structure, something near impossible by other means and which carries of wealth of critical but otherwise hard to obtain information, such as the sulfur chain length, the homogeneity, and the unpolymerized elemental sulfur content of the product polymer.
| Item Type: | Thesis (PhD) |
|---|---|
| Divisions: | Faculty of Science and Engineering > School of Physical Sciences |
| Depositing User: | Symplectic Admin |
| Date Deposited: | 23 Apr 2024 15:53 |
| Last Modified: | 23 Apr 2024 15:53 |
| DOI: | 10.17638/03178613 |
| Supervisors: |
|
| URI: | https://livrepository.liverpool.ac.uk/id/eprint/3178613 |
Dimensions
Dimensions
