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- Maurina Morais, Eduardo, 1989
(författare)
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Exploring new protic ionic liquids: From synthesis to fundamental properties
- 2023
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The ionic liquid community frequently leverages the selling point that more than a million new ionic liquids could conceivably be created. Nonetheless, the number of commercially available compounds is orders of magnitude lower. This highlights the fact that only a small number of all possible ionic liquids are actively being researched, a reality particularly noticeable in the niche field of protic ionic liquids. In such a scenario, research focusing on the development of even a small number of viable alternatives to the popular alkylammonium- and imidazolium-based cations could potentially have a big impact, by paving the way for the synthesis of new families of ionic liquids. However, for these new alternatives to be widely used by the community, they must be easy to synthesize and have desirable properties. In this thesis, I discuss the challenges that I have encountered and the lessons that I have learned while trying to explore the chemical space of protic ionic liquids. This exploration started with the development of a procedure for the synthesis of pure and dry protic ionic liquids, which was used to make new triazolium-based protic ionic liquids. Additionally, this first work highlights the importance of using air-free techniques to analyze these hygroscopic compounds. Later, these insights were used to develop a new setup for the determination of ionic conductivity in ionic liquids. The latter was used in conjunction with pulsed-field gradient nuclear magnetic resonance diffusion experiments and density functional theory experiments to understand the differences in transport properties between triazolium- and imidazolium-based protic ionic liquids. Finally, we once again turned our attention to the imidazolium cation and explored how simple modifications to its electronic structure, by means of functionalization with electron-withdrawing groups, can enhance its acidity, and how that affects the properties of these nitro- and cyano-functionalized protic ionic liquids. This thesis aims to highlight the importance of developing new methods for the synthesis and analysis of protic ionic liquids, as well as to explore how computational modeling can be used to rationalize the observed differences in the physicochemical properties of these compounds.
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- Maurina Morais, Eduardo, 1989, et al.
(författare)
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Solvent-free synthesis of protic ionic liquids. Synthesis, characterization and computational studies of triazolium based ionic liquids
- 2022
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Ingår i: Journal of Molecular Liquids. - : Elsevier BV. - 0167-7322. ; 360
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Tidskriftsartikel (refereegranskat)abstract
- A series of triazolium and imidazolium based protic ionic liquids were synthesized using a solvent-free method designed to address several limitations encountered with other commonly used methods. Using this method, pure (98–99% m/m) and dry (128–553 ppm of water) protic ionic liquids were synthesized (in a laboratory scale) without the need for purification methods that require heating the ionic liquid, hence avoiding the common issue of thermal decomposition. This method was also designed to allow for the accurate measurement of acid and base, and for the controlled mixing of both compounds, which is essential to avoid producing impure protic ionic liquids with excess of either acid or base. The system is constructed of only glass and chemically resistant polymer (PTFE and PVDF) parts, which avoid other contaminants that can result from unwanted reactions involving the reagents with common laboratory tools (metallic objects, paper, plastic, etc.). This process is described in detail in the paper as well as in a video. The resulting ionic liquids were carefully analyzed by spectroscopic and thermal methods designed to avoid water absorption, which is known to affect their properties. To complement this experimental characterization, computational chemistry tools were used to assess the ionic liquids’ properties, as well as to assign vibrational modes.
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- Maurina Morais, Eduardo, 1989
(författare)
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Synthesis of protic ionic liquids. Challenges and solutions for the synthesis of pure compounds.
- 2022
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The urgent need to diversify our energy matrix is responsible for a renewed interest in fuel cell technology, which can use hydrogen gas, a renewable green fuel, as an energy source. This technology is currently a commercially available option, however, it still requires technological improvements before it can be widely used for different applications. One way this technology could potentially be improved is by increasing its temperature range of operation by developing new, anhydrous proton conducting materials. Protic ionic liquids, which are organic salts with low melting temperatures, are interesting candidates for this application, since they can conduct protons in the operational conditions of fuel cells and without the need of water. These compounds can be synthesized by a simple acid-base neutralization reaction, but certain considerations must be taken in order to obtain high quality (dry and pure) protic ionic liquids. In this thesis, a series of triazolium and imidazolium based protic ionic liquids were synthesized using a solvent-free method designed to address several limitations encountered with other commonly used methods. Using this method, pure (98-99% m/m) and dry (128-553 ppm of water) protic ionic liquids were synthesized (in a laboratory scale) without the need for purification methods that require heating the ionic liquid, hence avoiding the common issue of thermal decomposition. This method was also designed to allow for the accurate measurement of acid and base, and for the controlled mixing of both compounds, which is essential to avoid producing impure protic ionic liquids with excess of either acid or base. The system is consists of only glass and chemically resistant polymer(PTFE and PVDF) parts, which avoids other contaminants that can result from unwanted reactions involving the reagents with common laboratory tools (metallic objects, paper, plastic, etc.). The resulting ionic liquids were carefully analyzed by spectroscopic and thermal analysis methods designed to avoid water absorption, which is known to affect their properties. To complement this experimental characterization, computational chemistry tools were used to assess the ionic liquids’ properties, as well as to assign vibrational modes.
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- Maurina Morais, Eduardo, 1989, et al.
(författare)
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Transport Properties of Protic Ionic Liquids Based on Triazolium and Imidazolium: Development of an Air-Free Conductivity Setup
- 2023
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Ingår i: Molecules. - 1420-3049 .- 1420-3049. ; 28:13
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Tidskriftsartikel (refereegranskat)abstract
- The dynamical properties of four protic ionic liquids, based on the ethyltriazolium ([C (Formula presented.) HTr (Formula presented.) ]) and the ethylimidazolium ([C (Formula presented.) HIm]) cation, were investigated. The associated anions were the triflate ([TfO]) and the bistriflimide ([TFSI]). Ionic conductivity values and self-diffusion coefficients were measured and discussed, extending the discussion to the concept of fragility. Furthermore, in order to allow the measurement of the ionic conductivity of very small volumes (<0.5 mL) of ionic liquid under an inert and dry atmosphere, a new setup was developed. It was found that the cation nature strongly affected the transport properties, the [C (Formula presented.) HTr (Formula presented.) ] cation resulting in slower dynamics than the [C (Formula presented.) HIm] one. This was concluded from both conductivity and diffusivity measurements while for both properties, the anion had a lesser effect. By fitting the conductivity data with the Vogel–Fulcher–Tammann (VFT) equation, we could also estimate the fragility of these ionic liquids, which all fell in the range of very fragile glass-forming materials. Finally, the slower dynamics observed in the triazolium-based ionic liquids can be rationalized by the stronger interactions that this cation establishes with both anions, as deduced from the frequency analysis of relevant Raman signatures and density functional theory (DFT) calculations.
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