Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
Investigation of side reactions during the conventional radical polymerisation of maleic anhydride and n-butyl vinyl ether
Thesis (MSc)--Stellenbosch University, 2021.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | English |
| Published: |
Stellenbosch : Stellenbosch University
2021
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613955992584192 |
|---|---|
| access_status_str | Open Access |
| author | Chagwedera, Ruvimbo Michelle |
| author2 | Klumperman, Bert |
| author_browse | Chagwedera, Ruvimbo Michelle Klumperman, Bert |
| author_facet | Klumperman, Bert Chagwedera, Ruvimbo Michelle |
| author_sort | Chagwedera, Ruvimbo Michelle |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MSc)--Stellenbosch University, 2021. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/110357 |
| institution | Stellenbosch University (South Africa) |
| language | English |
| last_indexed | 2026-06-10T12:44:22.712Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2021 |
| publishDateRange | 2021 |
| publishDateSort | 2021 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/110357 Investigation of side reactions during the conventional radical polymerisation of maleic anhydride and n-butyl vinyl ether Chagwedera, Ruvimbo Michelle Klumperman, Bert Pfukwa, Rueben Stellenbosch University. Faculty of Science. Dept. of Chemistry and Polymer Science. Free radical reactions Maleic anhydride Polymerization UCTD Thesis (MSc)--Stellenbosch University, 2021. ENGLISH ABSTRACT: The primary objective of this study is to investigate transfer to polymer reactions in the conventional radical polymerisation of maleic anhydride (MAnh) and n-butyl vinyl ether (n-BVE). Free radical polymerisation (FRP) of MAnh and n-BVE was conducted at 60 °C in an argon atmosphere using AIBN as the radical initiator. The volume of 1,4-dioxane was varied to achieve different initial monomer concentration. SEC and NMR techniques were employed to characterise the polymers. Transfer to polymer reactions results in the formation of the so-called mid chain radicals (MCRs). The occurrence of chain transfer to polymer was investigated through the characterisation of the side products formed. Among the various reactions that the MCRs can undergo, evidence of branching and β-fragmentation is presented in this study. The tertiary radicals on n-BVE units were more susceptible to monomer addition resulting in branch formation. Quaternary carbons were investigated using the attached proton test (ATP) experiment and the relative peak assignment was confirmed by gHSQC experiment. β-fragmentation resulted in the formation of macromonomers evidenced by the evolution of vinylic signals in the region 5.7 ppm to 7 ppm in the 1H NMR spectrum. Furthermore, an investigation into the dominant chain transfer mechanism was conducted by carrying out FRP in the presence of a preformed polymer. The preformed polymer was functionalised with pyrene to make it distinguishable from the fresh polymer sample that only contains MAnh and n-BVE. Any change in the profile of the dead polymer requires intermolecular chain transfer to have occurred. Changes in the molecular weight distribution (MWD) of the dead polymer was followed by SEC analysis with UV detection set at the absorption wavelength of pyrene. The profile of the dead polymer changed in all samples, including samples prepared at low initial monomer concentration. This observation suggests the occurrence of intermolecular chain transfer even at low initial monomer concentration, an observation that contradicts what has been previously reported for acrylate-based polymer system. This deviation is attributed to the structural rigidity of the anhydride ring that hinders free rotation of the polymer chains thus reducing the probability of intramolecular chain transfer. AFRIKAANSE OPSOMMING: Die hoofdoel van hierdie studie is om die oordrag na polimeerreaksies in die konvensionele radikale polimerisasie van maleïne-anhidried (MAnh) en n-butielvinieleter (n-BVE) te ondersoek. Vryradikale polimerisasie (FRP) van MAnh en n-BVE is by 60 °C in 'n argonatmosfeer uitgevoer met AIBN as die radikale inisieerder. Die volume 1,4-dioksaan is gevarieer om verskillende aanvanklike monomeerkonsentrasie te bereik. SEC en NMR tegnieke is gebruik om die polimere te karakteriseer. Oordrag na polimeerreaksies lei tot die vorming van die sogenaamde middelkettingradikale (MCRs). Die voorkoms van kettingoordrag na polimeer is ondersoek deur die karakterisering van die gevormde neweprodukte. Onder die verskillende reaksies wat die MCRs kan ondergaan, word bewyse van vertakking en β-fragmentering in hierdie studie aangebied. Die tersiêre radikale op n-BVE-eenhede was meer vatbaar vir monomeertoevoeging wat takvorming tot gevolg gehad het. Kwaternêre koolstowwe is ondersoek met behulp van die aangehegte proton toets (ATP) eksperiment en die relatiewe piek toewysing is bevestig deur gHSQC eksperiment. β-fragmentasie het gelei tot die vorming van makromonomome wat blyk uit die evolusie van viniese seine in die omgewing van 5,7 dpm tot 7 dpm in die 1H NMR spektrum. Verder is 'n ondersoek na die dominante kettingoordragmeganisme gedoen deur FRP in die teenwoordigheid van 'n voorgevormde polimeer uit te voer. Die voorgevormde polimeer is met pyreen gefunksionaliseer om dit te onderskei van die vars polimeermonster wat slegs MAnh en n-BVE bevat. Enige verandering in die profiel van die dooie polimeer vereis dat intermolekulêre kettingoordrag plaasgevind het. Veranderinge in die molekulêre gewigsverdeling (MWD) van die dooie polimeer is gevolg deur SEC-analise met UVopsporing wat ingestel is op die absorpsiegolflengte van pirene. Die profiel van die dooie polimeer het in alle monsters verander, insluitend monsters wat met lae aanvanklike monomeerkonsentrasie voorberei is. Hierdie waarneming dui op die voorkoms van intermolekulêre kettingoordrag selfs by lae aanvanklike monomeerkonsentrasie, 'n waarneming wat in stryd is met wat voorheen gerapporteer is vir akrielaat-gebaseerde polimeerstelsel. Hierdie afwyking word toegeskryf aan die strukturele rigiditeit van die anhidriedring wat die vrye rotasie van die polimeerkettings belemmer en sodoende die waarskynlikheid van intramolekulêre kettingoordrag verminder. Masters 2021-04-28T06:58:16Z 2023-05-03T03:00:11Z 2021-03 Thesis http://hdl.handle.net/10019.1/110357 en Stellenbosch University xi, 63 pages : illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Free radical reactions Maleic anhydride Polymerization UCTD Chagwedera, Ruvimbo Michelle Investigation of side reactions during the conventional radical polymerisation of maleic anhydride and n-butyl vinyl ether |
| title | Investigation of side reactions during the conventional radical polymerisation of maleic anhydride and n-butyl vinyl ether |
| title_full | Investigation of side reactions during the conventional radical polymerisation of maleic anhydride and n-butyl vinyl ether |
| title_fullStr | Investigation of side reactions during the conventional radical polymerisation of maleic anhydride and n-butyl vinyl ether |
| title_full_unstemmed | Investigation of side reactions during the conventional radical polymerisation of maleic anhydride and n-butyl vinyl ether |
| title_short | Investigation of side reactions during the conventional radical polymerisation of maleic anhydride and n-butyl vinyl ether |
| title_sort | investigation of side reactions during the conventional radical polymerisation of maleic anhydride and n butyl vinyl ether |
| topic | Free radical reactions Maleic anhydride Polymerization UCTD |
| url | http://hdl.handle.net/10019.1/110357 |
| work_keys_str_mv | AT chagwederaruvimbomichelle investigationofsidereactionsduringtheconventionalradicalpolymerisationofmaleicanhydrideandnbutylvinylether |