Principles of Cellulose Derivatization

Heinze, Thomas; Seoud, Omar A. El; Koschella, Andreas

doi:10.1007/978-3-319-73168-1_4

Cited by 10 publications

(10 citation statements)

References 107 publications

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“…These differences were further confirmed by AFM imaging using samples prepared by depositing diluted sample suspensions on freshly cleaved mica (Figure 2A, b and c). Although a few long platelets are present in multi-6F-EpC (7), their fraction is smaller than in EpC (8). As reported in the literature, 11,49 the thickness of EpC (8) platelets was found to be ~5 nm.…”

Section: Electron Microscopy (Em) and Atomic Force Microscopy (Afm)supporting

confidence: 53%

“…Figure 4 shows typical Raman spectra of 2F-EpC (4), 3F-EpC (5), 6F-EpC (6), multi-6F-EpC (7) and EpC (8). The bands located at ca.…”

Section: Raman Spectroscopymentioning

confidence: 99%

“…[3][4][5] Hence, the design of nanocellulose-based soft-matter materials relies on the formation of assembly-driven structures, and may prompt to changes in mechanical properties or bring additional functionality. [6][7][8][9][10] Production of cellulose nanocrystals and nanofibrillated cellulose, the main classes of nanocellulose, are both top-down methodologies, based on the isolation of nanocellulose from cellulosic biomass, which requires high energy consumption. 5 Moreover, functionalization of nanocellulose to meet requirements for specific applications often requires harsh chemical conditions (i.e.…”

Section: Introductionmentioning

confidence: 99%

“…Synthetic strategies for the regio-and stereoselective (deoxy)fluorination of monosaccharides have been successful. [30][31][32][33] In contrast, the corresponding top-down derivatization of cellulose 8,34 is complicated by solubility challenges, resulting in incomplete control of the sites and extent of fluorination. 35 The bottom-up chemical synthesis of structurally defined cellodextrins, including 3-fluorinated compounds, 32 has been achieved recently by automated glycan assembly.…”

Section: Introductionmentioning

confidence: 99%

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Bottom-up Chemoenzymatic Synthesis Towards Novel Fluorinated Cellulose-like Materials

Andrade¹,

Muñoz²,

Pergolizzi³

et al. 2020

Preprint

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Understanding the fine details of self-assembly of building blocks into complex hierarchical structures represents a major challenge en route to the design and preparation of soft matter materials with specific properties. Enzymatically-synthesised cellodextrins are known to have limited water solubility beyond DP9, a point at which they self-assemble into particles resembling the anti-parallel cellulose II crystalline packing. We have prepared and characterized a series of site-selectively fluorinated cellodextrins of different degrees of fluorination and substitution patterns by chemoenzymatic synthesis. The structural characterization of these materials at different length scales, combining advanced NMR and microscopy methods, showed that multiply 6-fluorinated cellodextrin chains assembled into particles presenting morphological and crystallinity features that are unprecedented for cellulose-like materials. In contrast, the introduction of a single fluorine atom per cellodextrin chain had a minor impact on materials structure. Our work emphasizes the strength of combining chemoenzymatic synthesis, fluorinated building blocks and advanced NMR and microscopy methods for the thorough characterization of hierarchical structures, leading to the controlled design of new biomaterials with specific properties.

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Section: Electron Microscopy (Em) and Atomic Force Microscopy (Afm)supporting

confidence: 53%

“…Figure 4 shows typical Raman spectra of 2F-EpC (4), 3F-EpC (5), 6F-EpC (6), multi-6F-EpC (7) and EpC (8). The bands located at ca.…”

Section: Raman Spectroscopymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Bottom-up Chemoenzymatic Synthesis Towards Novel Fluorinated Cellulose-like Materials

Andrade¹,

Muñoz²,

Pergolizzi³

et al. 2020

Preprint

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“…The processes of derivatization of natural polysaccharides are always accompanied by their preliminary activation in order to destroy the highly organized supramolecular structure, preventing the dissolution and melting of polysaccharides without decomposition [22]. These processes require the use of a large excess of organic solvents followed by their expensive regeneration and always begin as heterogeneous reactions in the preparation of hydrophobic derivatives [23,24]. Therefore, organic solid-state reactions based on the joint action of high pressure and shear strains in a solid mixture of reagents, including polymers [25][26][27], have numerous advantages since they are infinitely high-concentration reactions and proceed much more efficiently and faster frequently than solution reactions [28][29][30].…”

Section: Introductionmentioning

confidence: 99%

Hydrophobic Modification of Chitosan via Reactive Solvent-Free Extrusion

et al. 2021

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Hydrophobic derivatives of polysaccharides possess an amphiphilic behavior and are widely used as rheological modifiers, selective sorbents, and stabilizers for compositions intended for various applications. In this work, we studied the mechanochemical reactions of chitosan alkylation when interacting with docosylglycidyl and hexadecylglycidyl ethers in the absence of solvents at shear deformation in a pilot twin-screw extruder. The chemical structure and physical properties of the obtained derivatives were characterized by elemental analysis, FT-IR spectroscopy, dynamic light scattering, scanning electron microscopy, and mechanical tests. According to calculations for products soluble in aqueous media, it was possible to introduce about 5–12 hydrophobic fragments per chitosan macromolecule with a degree of polymerization of 500–2000. The length of the carbon chain of the alkyl substituent significantly affects its reactivity under the chosen conditions of mechanochemical synthesis. It was shown that modification disturbs the packing ability of the macromolecules, resulting in an increase of plasticity and drop in the elastic modulus of the film made from the hydrophobically modified chitosan samples.

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