Acid-catalyzed oligomerization via activated proton transfer to aromatic and unsaturated monomers in Nafion membranes: a step forward in the in situ synthesis of conjugated composite membranes
2016 (English)In: RSC Advances, ISSN 2046-2069, E-ISSN 2046-2069, Vol. 6, no 106, 104782-104792 p.Article in journal (Refereed) Published
An approach to perform controlled acid-catalyzed oligomerization via vapor pressure control of thereactions inside Nafion membranes is presented. The interaction of Nafion with several classes ofaromatic (pyrrol, furan, thiophene) and unsaturated (methyl-acetylene) gas phase monomers was studiedas a function of contact time and temperature by in situ vibrational (FTIR) and electronic (UV-Vis)spectroscopy with the support from theoretical linear response and time dependent DFT calculations tomonitor the vibrations and the effective number of conjugated double bonds. The formation ofH-bonded adduct as seen from IR spectroscopy transforms the hydrogen bonded species into positivelycharged oligomers through an activated proton transfer mechanism where oligomerization progressthrough increasing contact time with the respective gas phase reactants at room temperature. Theactivated proton transfer oligomerization proceeds through the stepwise growth propagation cycles viacarbocationic intermediates, finally leads to the formation of irreversible, conjugated charged oligomersas a product. The colored, conjugated oligomeric Nafion composite products are formed at roomtemperature as a function of reaction time and are irreversible after complete degassing of the gas phasereactants as well stable in ambient environment stored for many days in pure oxygen or air and cannotbe extracted with common solvents, appearing strongly encapsulated inside Nafion membranes. This iscrucial for future applications of the presented route for direct production of conjugated species insideNafion and thus production and control of composite membrane materials of interest in fuel cells andcatalysis.
Place, publisher, year, edition, pages
2016. Vol. 6, no 106, 104782-104792 p.
Engineering and Technology Nano Technology
IdentifiersURN: urn:nbn:se:uu:diva-307423DOI: 10.1039/c6ra23105eISI: 000388111900108OAI: oai:DiVA.org:uu-307423DiVA: diva2:1046925