Restricted dissolution and derivatization capacities of cellulose fibres under uniaxial elongational stress

Abstract

The authors are grateful to the publisher, Elsevier, for letting the manuscript being archived in this Open Access repository. The final publication is available at http://www.sciencedirect.com/International audienceCellulose is a future major source of materials and biofuel but its extraction and its chemical or enzymatic treatments are difficult, polluting and inefficient tasks. The accessibility of the reagents to cellulose chains is indeed limited. Classical evocated reasons for this lack of accessibility are pore structure, tight hydrogen bond arrays, crystallinity and presence of resistant materials like lignin. Studying dissolution of cotton hairs and regenerated cellulose fibres in various solvents under uniaxial tension, we found that tension is preventing these fibres to dissolve in chemicals that would dissolve the same cellulose fibres tension-free. We show that what is controlling dissolution is not the degree of swelling since, at the same degree of swelling, fibres under tension do not dissolve while fibres without tension do. An important result is that when a fibre under tension (thus swollen but not dissolved) is breaking, it is immediately dissolving. Under tension, when the solvent is present around cellulose chains, it is activated to solvate the chains only when tension stress is released. A chemical reaction like acetylation of cellulose fibre under tension also gives an interesting result. The degree of substitution remains very low while the same experiment performed without tension leads to higher degree of substitution followed by the dissolution of the fibre (even increasing further the DS due to homogeneous reaction). We postulate that the lack of dissolution capacity or reacting activity under tension can be due to the hampering of local conformational movements, cellulose chains being not able to perform axial movements. The availability of performing local conformational movements could be a main component of cellulose activation

Rotation and contraction of native and regenerated cellulose fibers upon swelling and dissolution: the role of morphological and stress unbalances

“…Regenerated cellulose fibers do not show any rotation and as was reported in a recent work (Le Moigne et al 2009), the morphology before total dissolution is a large homogeneous swelling (Fig. 7b).…”

“…To check the effect of preventing rotation (Fig. 5b), cotton hairs were fixed under low tension at both ends as was previously achieved in (Le Moigne et al 2009). …”

“…We recently reported (Le Moigne et al 2009) that the contraction forces occurring during swelling and dissolution are so high that they can break a fiber when it is maintained at its two ends. As shown on Fig.…”

Cellulose is not just cellulose: a review of dislocations as reactive sites in the enzymatic hydrolysis of cellulose microfibrils

“…hydrolysis within these regions would progress faster when a higher shear force was imparted. That the absence of tension in ''loose'' fibrils is important in increasing their reactivity was also discussed by LeMoigne et al (2010). They postulated that fibrils would have increased reactivity if the cellulose chains that form the fibrils were not under tension and thus were able to perform axial or local conformational movements.…”

Microwave‐Assisted Derivatization of Cellulose, 2 – The Surprising Effect of the Structure of Ionic Liquids on the Dissolution and Acylation of the Biopolymer

“…[1][2][3] It dissolves, however, in several "special" solvents without formation of covalent bonds, for example, in LiCl/ N,Ndimethylacetamide, [4][5][6][7] quaternary ammonium fl uorides/ dimethyl sulfoxide (DMSO), [ 8 ] and N -methylmorpholine-N -oxide. [ 9 ] Relatively recently, a new class of solvents, namely, ionic liquids (ILs), has been used in order to dissolve various types of cellulose, including microcrystalline cellulose (MCC) and fi brous cellulose (eucalyptus, bacterial cellulose, etc.). [10][11][12][13] Interest in these solvents has increased greatly due to their high chemical and thermal stabilities, nonfl ammability, and extremely low vapor pressure.…”