Probing cellulose amphiphilicity

Medronho, Bruno; Duarte, Hugo; Alves, Luís; Antunes, Filipe E.; Romano, Anabela; Lindman, Björn

doi:10.3183/npprj-2015-30-01-p058-066

Cited by 40 publications

(26 citation statements)

References 57 publications

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“…This enhancement is ≈90% larger in IL/DMSO than in IL/Sulfn, in agreement with the observed order of k 3 . The results of several MD simulations indicate that that the IL cation interacts with the nonpolar domains of cellulose through dispersion interactions, while interacting electrostatically with the anions bound in the polar domains of cellulose . The effect of these hydrophobic interactions on cellulose accessibility/reactivity cannot be assessed from our calculations.…”

Section: Resultsmentioning

confidence: 90%

“…Figure shows the average number of species present in the solvation shell of the oligomer, taken at 0.5 nm from its surface. In principle, these species affect cellulose reactivity due to, e.g., hydrogen bonding between the hydroxyl group of the AGU, the Cl − of the IL, and the dipole of the MS . As Figure shows, the average numbers of the ions in IL/DMSO are larger than in IL/Sulfn.…”

Section: Resultsmentioning

confidence: 97%

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Probing Cellulose Acetylation in Binary Mixtures of an Ionic Liquid with Dimethylsulfoxide and Sulfolane by Chemical Kinetics, Viscometry, Spectroscopy, and Molecular Dynamics Simulations

Nawaz

Pires

Arêas

et al. 2015

Macro Chemistry & Physics

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Acetylation of microcrystalline cellulose (MCC) by ethanoic anhydride (Ac2O) in mixtures of the ionic liquid (IL) 1‐allyl‐3‐methylimidazolium chloride and the (structurally related) molecular solvents (MSs), dimethylsulfoxide (DMSO) and sulfolane (Sulfn), is studied. Values of the reaction third‐order rate constants, k3, are calculated from conductivity data; they are linearly dependent on c(IL), due to (cellulose‐solvent) complex formation, as corroborated by Fourier Transform Infrared (FTIR) spectroscopy. The observed order of reactivity (IL/DMSO > IL/Sulfn) is explained by examining differences in the following properties of the MCC‐IL/MS solutions: macroscopic (viscosity); microscopic (empirical polarity and basicity), and from the results of molecular dynamics simulations. The latter indicate faster reactant diffusion in IL/DMSO and more interaction between the biopolymer hydroxyl groups and the ions of the IL.

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Section: Resultsmentioning

confidence: 90%

Section: Resultsmentioning

confidence: 97%

Probing Cellulose Acetylation in Binary Mixtures of an Ionic Liquid with Dimethylsulfoxide and Sulfolane by Chemical Kinetics, Viscometry, Spectroscopy, and Molecular Dynamics Simulations

Nawaz

Pires

Arêas

et al. 2015

Macro Chemistry & Physics

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“…The amphiphilic character of cellulose chains has been a topic of some interest, especially regarding its relevance to their dissolution . The effect of experimental conditions, such as temperature, the nature of the coagulation medium and its polarity, was shown to alter the interaction between the polymer chains . This characteristic also raised many scientific questions regarding the interaction between the enzyme and the substrate, focusing on hydrophilic and hydrophobic planes of the cellulose crystal .…”

Section: Introductionmentioning

confidence: 99%

Cellulose emulsions and their hydrolysis

Alfassi

Rein

Cohen

2018

J of Chemical Tech & Biotech

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BACKGROUND The abundance and bio‐renewability of cellulose renders it as a sustainable source for bio‐fuels, yet its potential is not fully exploited. There is current interest in combined enzymatic processes in emulsified systems. Previous work described the formation of a stable non‐crystalline cellulose coating on emulsified oil droplets. This raises significant questions regarding enzyme–substrate interactions in such systems. The aim of this work is to evaluate the ability of the enzyme to attack the cellulose shell on the surface of an oil droplet. This ability is foreseen to be relevant for advanced cellulose conversion processes, such as in the simultaneous extraction of reaction products and/or esterification. RESULTS Cellulose amphiphilicity was harnessed to fabricate oil‐in‐water emulsions using aqueous hydrogel dispersion fabricated from conventional alkaline solution. The cellulose shell on the surface of the oil droplets presents a huge non‐crystalline surface. Altering the cellulose/oil ratio effects the emulsion dimensions and the rate of enzymatic hydrolysis, where the conversion of emulsions having lower oil content proved similar to that of regenerated cellulose gels (81 and 77% hydrolyzed cellulose after 4 h, respectively). CONCLUSION Cellulose‐coated oil‐in‐water emulsion droplets are introduced as a novel substrate for cellulose hydrolysis for advanced conversion processes. © 2018 Society of Chemical Industry

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“…Additionally, for aqueous systems, addition of urea, well known for eliminating hydrophobic interactions in many situations, increases markedly the cellulose solubility (Cai and Zhang 2005;Bergenstråhle-Wohlert et al 2012;Xiong et al 2014;Wernersson et al 2015). Furthermore, surfactant addition has been found to strongly reduce cellulose-cellulose association controlling the regeneration (Yan and Gao 2008;Medronho et al 2015).…”

Section: Amphiphilicity and Charges Control The Dissolution And Regenmentioning

confidence: 99%

“…Recently, the "hydrogen bond mechanism" has been intensively discussed in the literature and has been challenged by general arguments regarding interactions, as well as by simulations and experimental studies (Glasser et al 2012;Medronho et al 2015). In addition, computer simulations are providing a deepened understanding (Bergenstråhle et al 2010).…”

Section: Questioning Of Hydrogen-bond Mechanismmentioning

confidence: 99%

The Subtleties of Dissolution and Regeneration of Cellulose: Breaking and Making Hydrogen Bonds

Lindman

Medronho

2015

BioRes

Self Cite

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Cellulose dissolution and regeneration are old topics that have recently gained renewed attention. This is reflected in both applications -earlier and novel -and in scientific controversies. There is a current discussion in the literature on the balance between hydrogen bonding and hydrophobic interactions in controlling the solution behavior of cellulose. Some of the key ideas are recalled. Keywords Challenges and OpportunitiesIt is evident that today's society is placing an increasing demand on materials, which, in turn, is leading to a "carbon shortage" in certain industries. Industries need to become more resource-conscious and make use of what already exists, namely using other renewable and sustainable resources. The agro-forestal and related industries can indeed raise many resource challenges for society and suppliers in the near future. In this context, it is thus predicable that cellulose, as a widely abundant and versatile biopolymer, will assume a leading role. Cellulose is found in many different forms and applications. However, in some of these applications, cellulose dissolution and regeneration are key (and challenging) aspects. Due to the complexity of the biopolymeric network as well as to the partially crystalline structure and extended noncovalent interactions among molecules, chemical processing of cellulose is rather difficult. A wide variety of suitable solvents for cellulose is already available (Medronho and Lindman 2014). Nevertheless, most solvent systems have important limitations, and there is an intense activity in both industrial and academic research aiming to optimize existing solvents and develop new ones. The problem of obtaining a picture of molecular processes is not trivial since cellulose solvents are of remarkably different nature, and thus the understanding of the subtle balance between the different interactions involved becomes non-trivial. Thermodynamics and Kinetics"Cellulose itself is insoluble in water due to the many and strong hydrogen bonds". This and other similar statements have been extensively repeated in specialized literature. Furthermore, it is typically argued that "the key to the solution of this problem of cellulose solubility is to search for a solvent that can destroy effectively the interchain hydrogen bonding in cellulose". It is unquestionable that in solid cellulose there are multiple hydrogen bonds between the molecules that need to be broken in order to achieve dissolution. However, cellulose molecules are not transferred from the solid state to a

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Probing cellulose amphiphilicity

Cited by 40 publications

References 57 publications

Probing Cellulose Acetylation in Binary Mixtures of an Ionic Liquid with Dimethylsulfoxide and Sulfolane by Chemical Kinetics, Viscometry, Spectroscopy, and Molecular Dynamics Simulations

Probing Cellulose Acetylation in Binary Mixtures of an Ionic Liquid with Dimethylsulfoxide and Sulfolane by Chemical Kinetics, Viscometry, Spectroscopy, and Molecular Dynamics Simulations

Cellulose emulsions and their hydrolysis

The Subtleties of Dissolution and Regeneration of Cellulose: Breaking and Making Hydrogen Bonds

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