Quantum-chemical simulation of interaction of polycaproamide with a lithium chloride solution in dimethylacetamide

Zelenkovskii, V. M.; Fen’ko, L. A.; Bildyukevich, A. V.

doi:10.1134/s1560090406010064

Cited by 4 publications

(8 citation statements)

References 8 publications

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“…In consideration of all the above results, the mechanisms of the variation of DMAc and Li + cations can be depicted as follows. When cellulose is dissolved in the DMAc/LiCl cosolvent system, hydrogen bonds can be formed between the hydroxyl protons and the Cl – anions, the Li + –Cl – ion pairs, − are thereafter split and the Li + cations are further solvated by DMAc, which led to the red shift of carbonyl stretch vibration and upfield shift of the 7 Li NMR signal and downfield shift of the carbonyl carbon 13 C NMR signal.…”

Section: Resultsmentioning

confidence: 99%

“…With consideration of the above results and discussion, the mechanism for the dissolution of cellulose in the DMAc/LiCl cosolvent system can be depicted as that shown in Figure . Li + and Cl – form ion pairs in DMAc/LiCl system. − When cellulose is dissolved in the DMAc/LiCl cosolvent system, the hydroxyl protons of cellulose will form strong hydrogen bonds with the Cl – , during which the intermolecular hydrogen-bonding networks of cellulose is broken with simultaneously splitting the Li + –Cl – ion pairs. Then, the Li + cations get further solvated by free DMAc molecules, and the further solvated Li + cations accompany the hydrogen-bonded Cl – to meet the electric balance.…”

Section: Resultsmentioning

confidence: 99%

“…In the DMAc/LiCl system, LiCl was confirmed to remain in the Li + –Cl – ion pair form. − Investigations on the cellulose/DMAc/LiCl system have provided information about the interactions between the dissolved cellulose and DMAc/LiCl system. When cellulose was dissolved in DMAc/LiCl, the Cl – anions were observed to replace the OH···O hydrogen bonds between cellulose chains with the OH···Cl – hydrogen bonds .…”

Section: Introductionmentioning

confidence: 99%

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Dissolution Mechanism of Cellulose in N,N-Dimethylacetamide/Lithium Chloride: Revisiting through Molecular Interactions

et al. 2014

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Understanding the interactions between solvent molecules and cellulose at a molecular level is still not fully achieved in cellulose/N,N-dimethylacetamide (DMAc)/LiCl system. In this paper, cellobiose was used as the model compound of cellulose to investigate the interactions in cellulose/DMAc/LiCl solution by using Fourier transform infrared spectroscopy (FTIR), (13)C, (35)Cl, and (7)Li nuclear magnetic resonance (NMR) spectroscopy and conductivity measurements. It was found that when cellulose is dissolved in DMAc/LiCl cosolvent system, the hydroxyl protons of cellulose form strong hydrogen bonds with the Cl(-), during which the intermolecular hydrogen bonding networks of cellulose is broken with simultaneous splitting of the Li(+)-Cl(-) ion pairs. Simultaneously, the Li(+) cations are further solvated by free DMAc molecules, which accompany the hydrogen-bonded Cl(-) to meet electric balance. Thereafter, the cellulose chains are dispersed in molecular level in the solvent system to form homogeneous solution. This work clarifies the interactions in the cellulose/DMAc/LiCl solution at molecular level and the dissolution mechanism of cellulose in DMAc/LiCl, which is important for understanding the principle for selecting and designing new cellulose solvent systems.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Dissolution Mechanism of Cellulose in N,N-Dimethylacetamide/Lithium Chloride: Revisiting through Molecular Interactions

et al. 2014

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“…When LiCl is added to DMAc, however, DMAc molecules surround Li + and leave Cl -free. [40][41][42] The Cl -ions penetrate between the cellulose chains by breaking up hydrogen bonds between hydroxyl groups because the ionic interaction is greater than hydrogen bonding. In consequence, the cellulose molecules are fully solvated by polarpolar interactions between polymer and solvent molecules.…”

Section: Resultsmentioning

confidence: 99%

Molecular Characterization on the Anomalous Viscosity Behavior of Cellulose Solutions in N,N-Dimethyl Acetamide and Lithium Chloride

Khaliq

Kim

2016

Macromol. Res.

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The physical properties of dilute cellulose solutions in N,N-dimethyl acetamide (DMAc) including 9 wt% lithium chloride (LiCl) were investigated in terms of concentration, temperature and molecular weight of cellulose. Over the concentration range of 0.01 to 2.5 g/dL, the viscosity of the cellulose solutions exhibited a lower critical solution temperature (LCST) behavior which proved thermoreversible between 30 and 60 o C. The LCST behavior was further supported by dynamic light scattering measurement. In the extremely dilute concentration range, 0.01 to 0.08 g/dL, the reduced viscosity (η red ) of cellulose solutions was increased with decreasing concentration. The anomalous coil expansion with decreasing concentration could be explained by the increase of the conductivity of cellulose solutions with decreasing concentration, which was also verified by dynamic light scattering experiment. In the concentration range of 0.1 and 2.5 g/dL, both cellulose solutions gave a drastic increase of η red in the vicinity of the critical concentration (C*), 0.9 g/dL. The slope of the curve of η red vs. concentration was higher for the cellulose of higher molecular weight, but it did not change with temperature between 30 and 60 o C.

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“…23−25 Quantum mechanical (QM) calculations of LiCl− DMA clusters also reveal strong DMA−Li + interactions. 26 For Cl − anions, experimental evidence does not indicate strong coupling to DMA. QM calculations suggest that the anions primarily interact with the methyl hydrogens of DMA.…”

Section: ■ Introductionmentioning

confidence: 99%

Preferential Interactions between Lithium Chloride and Glucan Chains in N,N-Dimethylacetamide Drive Cellulose Dissolution

2013

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Naturally occurring cellulose is crystalline as a consequence of the strong interactions between the glucan chains that comprise it and therefore is insoluble in most solvents. One of the few solvent systems able to dissolve cellulose is lithium chloride (LiCl) dissolved in N,N-dimethylacetamide (DMA). By an integrated application of all-atom molecular dynamics (MD) simulations, reaction path optimization, free-energy calculations, and a force-matching analysis of coarse-grained atomistic simulations, we establish that DMA-mediated preferential interactions of Li(+) cations and Cl(-) anions with glucan chains enable cellulose dissolution in LiCl/DMA. The relatively weak solvation of Li(+), Cl(-), and glucan chains by DMA results in strong effective interactions of Li(+) and Cl(-) ions with the glucans, leading to cellulose dissolution. The small size of the Li(+) cations allows them to strongly couple to multiple interaction sites on the glucan chains of cellulose, including the spatially restricted regions around the ether linkages connecting neighboring glucose residues. Li(+) cations were thus identified as the main component responsible for driving cellulose dissolution. The mechanism for explaining the solubility of cellulose in the LiCl/DMA system deduced from the analysis of atomistic-scale simulations conducted in this work is also consistent with most of the empirical observations related to cellulose dissolution in salt/amide solvent systems.

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Quantum-chemical simulation of interaction of polycaproamide with a lithium chloride solution in dimethylacetamide

Cited by 4 publications

References 8 publications

Dissolution Mechanism of Cellulose in N,N-Dimethylacetamide/Lithium Chloride: Revisiting through Molecular Interactions

Dissolution Mechanism of Cellulose in N,N-Dimethylacetamide/Lithium Chloride: Revisiting through Molecular Interactions

Molecular Characterization on the Anomalous Viscosity Behavior of Cellulose Solutions in N,N-Dimethyl Acetamide and Lithium Chloride

Preferential Interactions between Lithium Chloride and Glucan Chains in N,N-Dimethylacetamide Drive Cellulose Dissolution

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