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Synthesis and Characterization of Poly(phenylene oxide) Functionalized with various Imidazolium Cations via Alkyl Spacer units

Dalvig, Nils LU (2017) KTE720 20162
Centre for Analysis and Synthesis
Abstract
Anion exchange membranes consisting of a Poly(phenylene oxide) polymer backbone functionalized with various imidazolium cations, 1-methylimidazole, 1,2,4,5-tetramethyl-1H-imidazole, imidazo[1,2-a]pyridine, 1-methylbenzimidazole and 1-methyl-mesitylbenzimidazole, via alkyl spacer units were prepared and analyzed for anion conductivity, water absorption properties, cation aggregation, thermal stability and chemical stability.
Structural analysis via 1H NMR spectroscopy showed that the prepared membranes were completely functionalized and SAXS analysis showed that most samples formed cation aggregates, thus creating phase separation between the conductive functional groups and the nonconductive polymer backbone. Conductivity measurements... (More)
Anion exchange membranes consisting of a Poly(phenylene oxide) polymer backbone functionalized with various imidazolium cations, 1-methylimidazole, 1,2,4,5-tetramethyl-1H-imidazole, imidazo[1,2-a]pyridine, 1-methylbenzimidazole and 1-methyl-mesitylbenzimidazole, via alkyl spacer units were prepared and analyzed for anion conductivity, water absorption properties, cation aggregation, thermal stability and chemical stability.
Structural analysis via 1H NMR spectroscopy showed that the prepared membranes were completely functionalized and SAXS analysis showed that most samples formed cation aggregates, thus creating phase separation between the conductive functional groups and the nonconductive polymer backbone. Conductivity measurements carried out on the membranes in Br‒ form verified this and showed high conductivity values.
Thermal stability analysis showed that the samples had thermally decomposed at temperatures above operational levels in fuel cells. There were two degradation steps for all samples. The first step was the degradation and loss of the functional groups and the second corresponding to the decomposition of the polymer backbone.
Water uptake and conductivity results of the membranes in OH‒ form showed that only membranes functionalized with imidazolium cations TMeIm and MeMesBim maintained desirable properties. The rest had shown worse results than desired. This indicated some level of degradation had taken place while in the OH‒ form.
Stability analysis was carried out by immersing the membranes in 1 M aq NaOH at 60 °C for 4 and 8 days respectively. Results showed that the membranes functionalized with MeIm, ImPyr, and MeBim had undergone degradation. Due to lack of samples, an error during thermal analysis and poor solubility of membranes for structural analysis after undergoing stability testing, made it impossible to fully determine the chemical stability of the membranes functionalized with TMeIm and MeMesBim. (Less)
Popular Abstract (Swedish)
Anjonbytarmembran bestående av polyfenylenoxid funktionaliserad med följande imidasolgrupper, 1-metylimidasol (MeIm), 1,2,4,5-tetrametyl-1H-imidasol (TMeIm), imidaso[1,2-a]pyridin (ImPyr), 1-metylbensimidasol (MeBim) och 1-metyl-mesitylbensimidasol (MeMesBim), via en alkyl kedja tillverkades och analyserades med avseende på följande egenskaper; anjonisk ledningsförmåga, vattenabsorption, katjonaggregering, termisk stabilitet och kemisk stabilitet.
Strukturell analys via 1H NMR spektroskopi visade att membranen var fullständigt funktionaliserade och SAXS analys visade att katjonerna aggregerade i de flesta proverna. Detta tydde på att det bildades en fasseparation mellan polymerkedjan och de ledande funktionella grupperna.... (More)
Anjonbytarmembran bestående av polyfenylenoxid funktionaliserad med följande imidasolgrupper, 1-metylimidasol (MeIm), 1,2,4,5-tetrametyl-1H-imidasol (TMeIm), imidaso[1,2-a]pyridin (ImPyr), 1-metylbensimidasol (MeBim) och 1-metyl-mesitylbensimidasol (MeMesBim), via en alkyl kedja tillverkades och analyserades med avseende på följande egenskaper; anjonisk ledningsförmåga, vattenabsorption, katjonaggregering, termisk stabilitet och kemisk stabilitet.
Strukturell analys via 1H NMR spektroskopi visade att membranen var fullständigt funktionaliserade och SAXS analys visade att katjonerna aggregerade i de flesta proverna. Detta tydde på att det bildades en fasseparation mellan polymerkedjan och de ledande funktionella grupperna. Ledningsmätningar av membranen i Br‒ form bekräftade detta.
Termisk analys visade att alla prover bröts ner vid högre temperaturer än den typiska drifttemperaturen för en bränslecell. Det fanns två nedbrytningssteg för varje prov. Det första steget visade nedbrytning och dekomposition av den funktionella gruppen, emedan det andra steget visade på nedbrytningen av polymerkedjan.
Vattenupptag och jonledningsresultat för prover i OH‒ form visade att bara membranen som var funktionaliserade med TMeIm och MeMesBim hade bra egenskaper. De andra materialen visade sämre resultat än förväntat. Detta antydde att någon sorts nedbrytning skedde när membranet förvarades i OH‒ lösning.
Kemisk stabilitet mättes genom att förvara membranen i 1 M NaOH vattenlösning vid 60 °C i 4 respektive 8 dagar. Resultaten visade att membranen funktionaliserade med MeIm, ImPyr och MeBim bröts ner. På grund av brist på material var det inte möjligt att bedöma den kemiska stabiliteten för membranen som var funktionaliserad med TMeIm och MeMesBim. (Less)
Please use this url to cite or link to this publication:
author
Dalvig, Nils LU
supervisor
organization
course
KTE720 20162
year
type
H2 - Master's Degree (Two Years)
subject
keywords
polymer technology, polymer science
language
English
id
8913409
date added to LUP
2017-07-13 11:16:21
date last changed
2017-07-13 11:16:21
@misc{8913409,
  abstract     = {Anion exchange membranes consisting of a Poly(phenylene oxide) polymer backbone functionalized with various imidazolium cations, 1-methylimidazole, 1,2,4,5-tetramethyl-1H-imidazole, imidazo[1,2-a]pyridine, 1-methylbenzimidazole and 1-methyl-mesitylbenzimidazole, via alkyl spacer units were prepared and analyzed for anion conductivity, water absorption properties, cation aggregation, thermal stability and chemical stability. 
Structural analysis via 1H NMR spectroscopy showed that the prepared membranes were completely functionalized and SAXS analysis showed that most samples formed cation aggregates, thus creating phase separation between the conductive functional groups and the nonconductive polymer backbone. Conductivity measurements carried out on the membranes in Br‒ form verified this and showed high conductivity values.
Thermal stability analysis showed that the samples had thermally decomposed at temperatures above operational levels in fuel cells. There were two degradation steps for all samples. The first step was the degradation and loss of the functional groups and the second corresponding to the decomposition of the polymer backbone. 
Water uptake and conductivity results of the membranes in OH‒ form showed that only membranes functionalized with imidazolium cations TMeIm and MeMesBim maintained desirable properties. The rest had shown worse results than desired. This indicated some level of degradation had taken place while in the OH‒ form.
Stability analysis was carried out by immersing the membranes in 1 M aq NaOH at 60 °C for 4 and 8 days respectively. Results showed that the membranes functionalized with MeIm, ImPyr, and MeBim had undergone degradation. Due to lack of samples, an error during thermal analysis and poor solubility of membranes for structural analysis after undergoing stability testing, made it impossible to fully determine the chemical stability of the membranes functionalized with TMeIm and MeMesBim.},
  author       = {Dalvig, Nils},
  keyword      = {polymer technology,polymer science},
  language     = {eng},
  note         = {Student Paper},
  title        = {Synthesis and Characterization of Poly(phenylene oxide) Functionalized with various Imidazolium Cations via Alkyl Spacer units},
  year         = {2017},
}