On the mechanism of the unwanted acetylation of polysaccharides by 1,3-dialkylimidazolium acetate ionic liquids: part 2—the impact of lignin on the kinetics of cellulose acetylation

Abushammala, Hatem; Bacher, Markus; Korntner, Philipp; Potthast, Antje; Rosenau, Thomas; Laborie, Marie‐Pierre

doi:10.1007/s10570-017-1322-x

Cited by 19 publications

(19 citation statements)

References 19 publications

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“…The surface energy of CNCs is dependent on the carbon backbone of the cellulose chains but more importantly on the surface hydroxyl groups, which are more often subjected to chemical and physical treatments [10,43]. Small degrees of chemical modifications have been shown to have a major impact on the surface properties of cellulose [44].…”

Section: Resultsmentioning

confidence: 99%

Nano-Brushes of Alcohols Grafted onto Cellulose Nanocrystals for Reinforcing Poly(Butylene Succinate): Impact of Alcohol Chain Length on Interfacial Adhesion

Abushammala

2020

Polymers

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Despite the many interesting properties of cellulose nanocrystals (CNCs), their hydrophilicity is one of the main challenges for their processing with hydrophobic polymers and matrices. To overcome this challenge, this paper describes the preparation of brush-like CNCs with tailored surface properties by grafting alcohols of different chain lengths onto their surfaces. Ethanol, 1-butanol, 1-hexanol, and 1-octanol were grafted on the CNC surface using 2,4-toluene diisocyanate (TDI) as a linker. The CNCs were characterized for their structural, morphological, surface, and thermal properties. Because of the grafting, the water contact angle of the CNCs significantly increased from 32° to up to 120°, which was dependent on the chain length of the grafted alcohol. The thermal stability of the CNCs was also improved, mainly as a result of the reaction of TDI with the CNC hydroxyl groups. Later, the CNCs were used to reinforce films of poly(butylene succinate) (PBS), which were then characterized using dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA). An increase of up to two-fold in the storage modulus was observed using DMA, which was dependent on the chain length of the grafted alcohol. However, no change in the glass transition temperature or degradation temperature of PBS was detected. This approach is proved efficient for tailoring the surface properties of CNCs towards excellent interfacial adhesion in their composites.

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Section: Resultsmentioning

confidence: 99%

Nano-Brushes of Alcohols Grafted onto Cellulose Nanocrystals for Reinforcing Poly(Butylene Succinate): Impact of Alcohol Chain Length on Interfacial Adhesion

Abushammala

2020

Polymers

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“…Analysis of this cellulose-rich residue from [EMIm][OAc] treatment results in acetyl value of 3 wt % (back-titration). This might arise from the inherent xylan and/or lignin composition of the residue or from an acetylation reaction occurring during pulping as previously observed with [EMIm][OAc] treatment and its thermal degradation product 1-acetylimidazol [8,9]. It appears that some of the native TC acetyl groups, value (2.53 ± 0.06 mmol/g), have partitioned between lignin (0.51 ± 0.01 mmol/g), cellulose rich pulp (0.7 ± 0.02 mmol/g) and other fractions cleaved during the process.…”

Section: Discussionmentioning

confidence: 99%

“…Although acetyl groups were detected in the cell wall of Miscanthus x giganteus , however, after pulping with 1-butylimidazolium hydrogen sulfate, acetyl groups were not detected in the isolated lignin [7]. In the case of wood pulping with dialkyl imidazolium salts such as 1-ethyl-3-methylimidazolium acetate ([EMIm][OAc]), acetyl transfer was revealed as an important side-reaction [8,9,10]. [EMIm][OAc] swells lignocellulose effectively, eventually causing derivatization of its structural polymers [11,12,13].…”

Section: Introductionmentioning

confidence: 99%

“…In particular, xylan deacetylation and lignin acetylation have been observed [10]. In [EMIm][OAc], imidazole, a degradation product of imidazolium, plays the role of acetyl transfer onto cellulose [8], a side-reaction catalyzed by lignin [9]. Although the source of the acetic acid is not known, acetate cleavage in lignocellulose and the presence of acetates in [EMIm][OAc] are both potential sources of acetic acid for this side-reaction [9].…”

Section: Introductionmentioning

confidence: 99%

“…In [EMIm][OAc], imidazole, a degradation product of imidazolium, plays the role of acetyl transfer onto cellulose [8], a side-reaction catalyzed by lignin [9]. Although the source of the acetic acid is not known, acetate cleavage in lignocellulose and the presence of acetates in [EMIm][OAc] are both potential sources of acetic acid for this side-reaction [9]. When pulping a grass with [EMIm][OAc], any native acetylation of lignin (and of heteropolysaccharides) will thus likely affect the process and resulting lignin structure.…”

Section: Introductionmentioning

confidence: 99%

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Acetyl Groups in Typha capensis: Fate of Acetates during Organosolv and Ionosolv Pulping

et al. 2018

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During biomass fractionation, any native acetylation of lignin and heteropolysaccharide may affect the process and the resulting lignin structure. In this study, Typha capensis (TC) and its lignin isolated by milling (MWL), ionosolv (ILL) and organosolv (EOL) methods were investigated for acetyl group content using FT-Raman, 1 H NMR, 2D-NMR, back-titration, and Zemplén transesterification analytical methods. The study revealed that TC is a highly acetylated grass; extractive free TC (TC extr ) and TC MWL exhibited similar values of acetyl content: 6 wt % and 8 wt % by Zemplén transesterification, respectively, and 11 wt % by back-titration. In contrast, lignin extracted from organosolv and [EMIm][OAc] pulping lost 80% of the original acetyl groups. With a high acetyl content in the natural state, TC could be an interesting raw material in biorefinery in which acetic acid could become an important by-product.

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On the Mechanism of the Reactivity of 1,3‐Dialkylimidazolium Salts under Basic to Acidic Conditions: A Combined Kinetic and Computational Study

et al. 2018

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Comprehensive spectroscopic kinetic studies illustrate an alternative mechanism for the traditional free-carbene intermediated H/D exchange reaction of 1,3-dialkylimidazolium salts under neutral (D 2 O) and acidic conditions (DCl/ D 2 O3 5wt% solution). The deuteration of high purity [bmim]Cl in D 2 Oi ss tudied at different temperatures,i n absence of catalyst or impurities,toyield an activation energy. DFT transition-state modelling,o fasmall water cluster and [bmim] cation, also yields an activation energy which strongly supports the proposed mechanism. The presence of basic impurities are shown to significantly enhance the exchange reaction, which brings into question the need for further analysis of technical purities of ionic liquids and the implications for aw ide range of chemical reactions in such media.Supportinginformation and the ORCID identification number(s) for the author(s) of this article can be found under: https://doi.

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On the mechanism of the unwanted acetylation of polysaccharides by 1,3-dialkylimidazolium acetate ionic liquids: part 2—the impact of lignin on the kinetics of cellulose acetylation

Cited by 19 publications

References 19 publications

Nano-Brushes of Alcohols Grafted onto Cellulose Nanocrystals for Reinforcing Poly(Butylene Succinate): Impact of Alcohol Chain Length on Interfacial Adhesion

Nano-Brushes of Alcohols Grafted onto Cellulose Nanocrystals for Reinforcing Poly(Butylene Succinate): Impact of Alcohol Chain Length on Interfacial Adhesion

Acetyl Groups in Typha capensis: Fate of Acetates during Organosolv and Ionosolv Pulping

On the Mechanism of the Reactivity of 1,3‐Dialkylimidazolium Salts under Basic to Acidic Conditions: A Combined Kinetic and Computational Study

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