Rheological and NMR Studies of Cellulose Dissolution in the Ionic Liquid BmimAc

Lefroy, Katherine S.; Murray, Brent S.; Ries, Michael E.

doi:10.1021/acs.jpcb.1c02848

Cited by 16 publications

(16 citation statements)

References 66 publications

(188 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…When oil was added after cellulose dissolution (method A, inset Figure 4 b), the differences were relatively small but slightly more significant compared to BmimAc–oil mixtures in the absence of cellulose ( Figure 3 b), but when solutions were prepared by adding oil to BmimAc before cellulose dissolution (method B, Figure 4 c), Δδ was at least 10 times higher for the acidic proton H1 (compared to method A). Resonances shifted downfield (increased in δ) with the addition of oil, which surprisingly is the opposite of what happens when cellulose is dissolved in BmimAc 69 (where resonances shift upfield, Figure 3 c). This downfield shift indicates a decrease in electron density around the aromatic protons and therefore strengthening of the cation–anion H-bond, since the aromatic protons (H1, H2, and H3) are much more affected by the addition of oil compared to the rest of the IL protons.…”

Section: H Nmrmentioning

confidence: 82%

“…This has also been described as breakdown of IL clusters and ultimately ion pairs, which exist in the pure BmimAc solution but are disrupted when small amounts of cellulose are added (0.1−1 wt %). 69 Unlike cellulose, oil appears to lack any significant interaction with the IL and there is negligible change to cation−anion Hbonding, suggesting that oil has a minimal effect on IL clusters. Therefore, it was speculated that at these concentrations, oil will have little or no effect on the ability of BmimAc to dissolve cellulose, 68 unlike more polar solvents such as water.…”

Section: ■ Results and Discussionmentioning

confidence: 98%

“…Consequently, weakening of the cation–anion H-bond occurs as indicated by an increase in electron density around the aromatic protons (H1 in particular), leading to the upfield movement of δ (as indicated by a negative Δδ, Figure c). This has also been described as breakdown of IL clusters and ultimately ion pairs, which exist in the pure BmimAc solution but are disrupted when small amounts of cellulose are added (0.1–1 wt %) . Unlike cellulose, oil appears to lack any significant interaction with the IL and there is negligible change to cation–anion H-bonding, suggesting that oil has a minimal effect on IL clusters.…”

Section: H Nmrmentioning

confidence: 99%

“…Any weak cation–oil interactions are replaced with stronger cellulose–oil interactions, while the majority of the cellulose (dispersed in BmimAc) begins to dissolve. When oil is added after cellulose dissolution, the cellulose has already been molecularly dissolved, and therefore, the solution viscosity is much greater compared to pure BmimAc . Therefore, oil cannot be distributed as uniformly as in the absence of cellulose, and the volume of cellulose–oil interactions is reduced.…”

Section: H Nmrmentioning

confidence: 99%

See 3 more Smart Citations

Effect of Oil on Cellulose Dissolution in the Ionic Liquid 1-Butyl-3-methyl Imidazolium Acetate

2022

View full text Add to dashboard Cite

While ionic liquids (ILs) are well known to be excellent solvents for cellulose, the exact mechanism of dissolution has been a much disputed topic in recent years and is still not completely clear. In this work, we add to the current understanding and highlight the importance of hydrophobic interactions, through studying cellulose dissolution in mixtures of 1-butyl-3-methyl imidazolium acetate (BmimAc) and medium-chain triglyceride (MCT) oil. We demonstrate that the order in which constituents are mixed together plays a key role, through nuclear magnetic resonance (NMR) spectroscopic analysis. When small quantities of MCT oil (0.25–1 wt %) were introduced to BmimAc before cellulose, the effect on BmimAc chemical shift values was much more significant compared to when the cellulose was dissolved first, followed by oil addition. Rheological analysis also showed small differences in the viscosities of oil–cellulose–BmimAc solutions, depending on the order the constituents were added. On the other hand, no such order effect on the NMR results was observed when cellulose was replaced with cellobiose, suggesting that this observation is unique to the macromolecule. We propose that a cellulose–oil interaction develops but only when the cellulose structure has a sufficient degree of order and not when the cellulose is molecularly dispersed, since the hydrophobic cellulose plane is no longer intact. In all cases, cellulose–BmimAc–oil solutions were stable for at least 4 months. To our knowledge, this is the first work that investigates the effect of oil addition on the dissolving capacity of BmimAc and highlights the need for further re-evaluation of accepted mechanisms for cellulose dissolution in ILs.

show abstract

Section: H Nmrmentioning

confidence: 82%

Section: ■ Results and Discussionmentioning

confidence: 98%

Section: H Nmrmentioning

confidence: 99%

Section: H Nmrmentioning

confidence: 99%

See 2 more Smart Citations

Effect of Oil on Cellulose Dissolution in the Ionic Liquid 1-Butyl-3-methyl Imidazolium Acetate

2022

View full text Add to dashboard Cite

show abstract

“…Herein, we apply our method to ionic liquid solutions of cellulose, − PEO, , PMMA, and P(AN- co -IA) . The repeat unit chemical structures of these polymers are shown in Figure .…”

Section: Data Analysismentioning

confidence: 99%

Universality in Solution Properties of Polymers in Ionic Liquids

Sayko

Jacobs

Dobrynin

2022

ACS Appl. Polym. Mater.

View full text Add to dashboard Cite

Knowledge of the interaction parameters for polymers in different solvents is crucial for exploring the viscoelastic properties and processing capabilities of polymer solutions. Here, we apply a scaling theory of semidilute polymer solutions to quantify the solution properties of cellulose, poly(ethylene oxide), poly(methyl methacrylate), and poly-(acrylonitrile-co-itaconic acid) in different ionic liquids. The starting point of our approach is a scaling relationship between the solution correlation length ξ = lg ν /B and the number of repeat units g in a correlation blob for polymers with a repeat unit projection length l, chain segment fractal dimension 1/ν, and the corresponding interaction parameter B describing polymer−solvent affinity and assuming values B g , B th , and 1 in different solution regimes. In the framework of this approach, we obtain crossover concentrations to the semidilute solution regime, c*, the solution regime of overlapping thermal blobs, c th , and the concentrated solution regime, c**. The method takes advantage of the linear relationship of the specific viscosity η sp with the number of correlation blobs per chain N w /g in the unentangled Rouse regime for polymers with a weight-average degree of polymerization N w . The application of our approach to entangled solutions provides the chain packing number, P e , and completes the set of parameters {B g , B th , and P e } that uniquely describes the static and dynamic solution properties for a given polymer/solvent pair. This approach also allows us to identify a trend relating the B g parameter to the van der Waals volume of the ionic liquid anion, analogous to the Hofmeister series, and to obtain the temperature and solvent type dependence of the polymer excluded volume and Kuhn length.

show abstract

Broadband NMR Relaxometry as a Powerful Technique to Study Molecular Dynamics of Ionic Liquids

Fraenza

Greenbaum

2023

ChemPhysChem

View full text Add to dashboard Cite

Fast field cycling nuclear magnetic resonance (FFC NMR) relaxometry technique has been demonstrated to be a useful analytical tool to investigate molecular dynamics in very diverse systems during the last decades. Of particular importance has been its application in studying ionic liquids, upon which this review article is based. Some of the research carried out on ionic liquids during the last ten years using this technique is highlighted in this article with the aim of promoting the favorable features of FFC NMR applied toward understanding dynamics of complex systems.

show abstract

Rheological and NMR Studies of Cellulose Dissolution in the Ionic Liquid BmimAc

Cited by 16 publications

References 66 publications

Effect of Oil on Cellulose Dissolution in the Ionic Liquid 1-Butyl-3-methyl Imidazolium Acetate

Effect of Oil on Cellulose Dissolution in the Ionic Liquid 1-Butyl-3-methyl Imidazolium Acetate

Universality in Solution Properties of Polymers in Ionic Liquids

Broadband NMR Relaxometry as a Powerful Technique to Study Molecular Dynamics of Ionic Liquids

Contact Info

Product

Resources

About