Non-covalent interactions of imidazolium-based ionic liquids with model pyrrolidones revealed by FTIR spectroscopy and quantum chemical model calculations

Result code in IS VaVaI

<a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F61389013%3A_____%2F20%3A00524775" target="_blank" >RIV/61389013:_____/20:00524775 - isvavai.cz</a>

Result on the web

<a href="https://www.sciencedirect.com/science/article/pii/S0167732220314021?via%3Dihub" target="_blank" >https://www.sciencedirect.com/science/article/pii/S0167732220314021?via%3Dihub</a>

DOI - Digital Object Identifier

<a href="http://dx.doi.org/10.1016/j.molliq.2020.113445" target="_blank" >10.1016/j.molliq.2020.113445</a>

Result language

angličtina

Original language name

Non-covalent interactions of imidazolium-based ionic liquids with model pyrrolidones revealed by FTIR spectroscopy and quantum chemical model calculations

Original language description

Certain ionic liquids (ILs), such as 1-butyl-3-methylimidazolium chloride (bmimCl) and 1-ethyl-3-methylimidazolium acetate (emimAc), are potent cellulose solvents, but the high viscosity of the resulting solutions is problematic in many applications. Organic co-solvents are often employed to alleviate this problem. However, our understanding of the intermolecular interactions determining the IL/co-solvent mixture performance is very limited, hampering the further development of this class of cellulose solvents. Herein, we applied infrared spectroscopy (IR), Raman spectroscopy, and quantum chemical model calculations to investigate the intermolecular interactions in differently concentrated mixtures of bmimCl and emimAc with amidic co-solvents, N-methyl-2-pyrrolidone (NMP) and N-vinyl-2-pyrrolidone (NVP). Based on the detailed analysis of the vibrational spectra of individual mixture components and the improved assignment of the relevant characteristic bands, we determined that bmim+-co-solvent and emim+-co-solvent associates, stabilized by the hydrogen bonds between amidic carbonyl oxygens and the CH groups of the imidazolium rings, are formed in the mixtures. In addition, the data pointed to concomitant disruption of the H-bonds between the IL counterions as the co-solvent concentration was increased, which may indicate partial dissociation of the IL ion pairs. Further, through an extensive deconvolution analysis, we quantified the molar fractions of the co-solvent molecules involved in the associate formation, finding that this fraction is significantly lower for emimAc than for bmimCl mixtures at all the studied concentrations. On the other hand, the influence of the amidic co-solvent structure was negligible, suggesting that also other (aprotic) amides may be applicable as co-solvents. Furthermore, the calculated molar ratio of IL to interacting co-solvent molecules highlighted the possible differences in the associate stoichiometry. The findings indicate that the lower affinity of the IL to co-solvents in emimAc-based mixtures may lead to the retaining of larger IL-rich clusters and, consequently, the comparatively better performance of the system in cellulose dissolution. Finally, increased temperature was found to influence all the studied systems similarly, inflicting about 20% decrease in the fraction of interacting co-solvent molecules at 85 °C as compared to room temperature. In summary, the results of this study provide important implications for the design of new solvent systems for cellulose dissolution.

Czech name

—

Czech description

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Type

J_imp - Article in a specialist periodical, which is included in the Web of Science database

CEP classification

—

OECD FORD branch

10404 - Polymer science

Project

<a href="/en/project/GA17-03810S" target="_blank" >GA17-03810S: Role of non-covalent interactions in miscibility of cellulose with synthetic polymers in complex solvent systems</a><br>

Continuities

I - Institucionalni podpora na dlouhodoby koncepcni rozvoj vyzkumne organizace

Publication year

2020

Confidentiality

S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Name of the periodical

Journal of Molecular Liquids

ISSN

0167-7322

e-ISSN

—

Volume of the periodical

312

Issue of the periodical within the volume

15 August

Country of publishing house

NL - THE KINGDOM OF THE NETHERLANDS

Number of pages

14

Pages from-to

1-14

UT code for WoS article

000559968600056

EID of the result in the Scopus database

2-s2.0-85085926215