Determination of empirical polarity parameters of the cellulose solvent N,N‐dimethylacetamide/LiCl by means of the solvatochromic technique

Spange, Stefan; Reuter, Anett; Vilsmeier, Elmar; Heinze, Thomas; Keutel, Dietmar; Linert, Wolfgang

doi:10.1002/(sici)1099-0518(199808)36:11<1945::aid-pola30>3.3.co;2-v

Cited by 22 publications

(28 citation statements)

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“…The above-mentioned dependence is also relevant to the properties/applications of the solid derivatives, e.g., films and fibers employed in separation and reverse osmosis (Cheng 1993;Kesting et al 1979); dyeing (Stana-Kleinschek et al 1999;Zollinger 1991); miscibility with other polymers, and chemical reactivity in further derivatization reactions (Klemm et al 1998;Spange et al 1998); gas sorption (Puleo et al 1989); nonlinear optics (Khudyakov et al 2009);and nano-composites (Moura et al 2011). Recently, we have shown that the properties of esters films of cellulose can be conveniently probed by using perichromic dyes, hereafter designated as ''probes''.…”

Section: Introductionmentioning

confidence: 99%

Employing perichromism for probing the properties of carboxymethyl cellulose films: an expedient, accurate method for the determination of the degree of substitution of the biopolymer derivative

et al. 2011

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The properties of films of carboxymethyl cellulose, CMC, of different degree of substitution, DS, have been examined by the use of perichromic indicators (probes). The film properties that have been determined are: empirical polarity, E T (33); ''acidity'', a; ''basicity'', b; and dipolarity/polarizability, p*. This has been achieved by employing the following perichromic probes: 4-nitroaniline, 4-nitroanisole, 4-nitro-N,N-dimethylaniline, and 2,6-dichloro-4-(2,4, 6-triphenyl-pyridinium-1-yl)phenolate, WB. The correlations between both E T (33)-or p* and DS were found to be linear; that between b and DS is a second order polynomial; no obvious correlation was found between a and DS. The polarities of CMC films are in the range of those of butyl alcohols. As models for CMC, we have employed cellulose plus CMC of high DS; oxidized cellulose with degree of oxidation = 0.5; sodium glucuronate. The former model behaved akin to CMC, but the plots of the perichromic properties versus DS showed different slopes/intercepts. FTIR data and molecular dynamics simulations on the solvation of WB have shown that this difference can be traced to more efficient hydrogen bonding between the film of the model and the probe. This affects the intra-molecular charge-transfer energy of the latter, leading to different responses to the variation of DS. Based on the excellent linear correlation between E T (33) and DS, for CMC from different origins, we suggest that perichromism is a simple, accurate, and expedient alternative for the determination of DS of the biopolymer derivative.

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Section: Introductionmentioning

confidence: 99%

Employing perichromism for probing the properties of carboxymethyl cellulose films: an expedient, accurate method for the determination of the degree of substitution of the biopolymer derivative

et al. 2011

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“…(DMAc) n ), and thus strong interactions between Li ? (DMAc) n Cl -ÁÁÁHO-Cell are believed to be responsible for cellulose dissolution (Morgenstern et al 1992;Spange et al 1998). When interactions between the anion and the OH groups of cellulose become very week by changing the electrolyte from LiCl to LiBr (the solution medium also becomes less basic), then LiBr/DMAc cannot dissolve cellulose and falls into regime A (Spange et al 1998).…”

Section: Connection Of Dissolution Efficiency To Cellulosesolvent Intmentioning

confidence: 99%

Cellulose dissolution: insights on the contributions of solvent-induced decrystallization and chain disentanglement

2016

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The dissolution of cellulose is a critical step for the efficient utilization of this renewable resource as a starting material for the synthesis of high value-added functional polymers and chemicals and also for biofuel production. The recalcitrance of semicrystalline cellulose microfibrils presents a major barrier to cellulose dissolution. Despite research efforts, important aspects of cellulose dissolution such as solvent-induced decrystallization and chain disentanglement are not well-understood. Here we address these fundamental issues with the practical goal of gaining insights into the swelling and dissolution of cellulose that cannot be obtained from macroscopic experimental data. To this end, we have used a newly-developed phenomenological model that captures the phenomena governing the dissolution of semicrystalline polymers as well as the thermodynamics and kinetics of dissolution. This model fits well experimental data for swelling and dissolution of cotton fibers in the ionic liquid [bmim]Cl, and allows the quantification of two important aspects, i.e., solvent effectiveness in cellulose (1) decrystallization and (2) chain disentanglement, the balance of which controls the mechanism and kinetics of cellulose dissolution. The activation parameters of cellulose decrystallization, estimated using the obtained decrystallization constant values, reveal that the decrystallization of cellulose in [bmim]Cl is associated with positive enthalpy and entropy and it is also very sensitive to temperature. When the solvent effectiveness in the disruption of cellulose crystals is relatively lower than its ability to disentangle the chains, the kinetics of dissolution are controlled by decrystallization. Furthermore, conditions that facilitate cellulose chain disentanglement, in addition to increasing the rate of dissolution, can result in faster decrystallization. The solvent effectiveness in chain disentanglement is the only factor that determines the decrease of the cellulose fiber radius. In cases where the fiber dissolution rate is lower than the decrystallization rate, the dissolution of cellulose is mostly controlled by the solvent ability to disentangle the chains. The insights obtained from this study improve the understanding of cellulose-solvent interactions underlying decrystallization and disentanglement and their contributions in controlling the kinetics of cellulose swelling and dissolution.

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“…Numerous solvatochromic indicator dyes are available [25]. In many reports where new solvents for cellulose are being evaluated, the Kamlet-Taft parameters are held as highly important [26][27][28][29]. In Table 1 Water cannot be used to break the bonds in cellulose, yet both water-water, carbohydratewater and carbohydrate-carbohydrate hydrogen bond strengths are around 5kcal/mol [32].…”

Section: Solubility Of Cellulosementioning

confidence: 99%

Direct Dissolution of Cellulose: Background, Means and Applications

Olsson¹,

Westman²

2013

Cellulose - Fundamental Aspects

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Determination of empirical polarity parameters of the cellulose solvent N,N‐dimethylacetamide/LiCl by means of the solvatochromic technique

Cited by 22 publications

References 0 publications

Employing perichromism for probing the properties of carboxymethyl cellulose films: an expedient, accurate method for the determination of the degree of substitution of the biopolymer derivative

Employing perichromism for probing the properties of carboxymethyl cellulose films: an expedient, accurate method for the determination of the degree of substitution of the biopolymer derivative

Cellulose dissolution: insights on the contributions of solvent-induced decrystallization and chain disentanglement

Direct Dissolution of Cellulose: Background, Means and Applications

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