The relevance of structural features of cellulose and its interactions to dissolution, regeneration, gelation and plasticization phenomena

Abstract

aCellulose is the most abundant polymer and a very important renewable resource. Since cellulose cannot be shaped by melting, a major route for its use for novel materials, new chemical compounds and renewable energy must go via the solution state. Investigations during several decades have led to the identification of several solvents of notably different character. The mechanisms of dissolution in terms of intermolecular interactions have been discussed from early work but, even on fundamental aspects, conflicting and opposite views appear. In view of this, strategies for developing new solvent systems for various applications have remained obscure. There is for example a strong need for using forest products for higher value materials and for environmental and cost reasons to use water-based solvents. Several new water-based solvents have been developed recently but there is no consensus regarding the underlying mechanisms. Here we wish to address the most important mechanisms described in the literature and confront them with experimental observations. A broadened view is helpful for improving the current picture and thus cellulose derivatives and phenomena such as fiber dissolution, swelling, regeneration, plasticization and dispersion are considered. In addition to the matter of hydrogen bonding versus hydrophobic interactions, the role of ionization as well as some applications of new knowledge gained are highlighted.

The structure of galactoglucomannan impacts the degradation under alkaline conditions

“…This can be explained by that the OH 2 hydroxyl group is equatorial in Glc, but axial in Man. Similar coordination has been seen previously in simulations of cellobiose, and has been suggested to induce deprotonation of cellulose in alkali solvents systems (Bialik et al 2016;Lindman et al 2017). Furthermore, Glc experienced an even higher coordination of OH -in the Gal substituted oligomer (MGLM), possibly a consequence of that the Glc and Gal groups can coordinate a OH -together as showed in Fig.…”

Cellulose in Ionic Liquids and Alkaline Solutions: Advances in the Mechanisms of Biopolymer Dissolution and Regeneration

“…Physical dissolution of cellulose requires disruption of the inter-and intramolecular H-bonds between the hydroxyl groups of the AGUs, as well as the solvophobic interactions present [40]. Briefly, the dissolution proceeds by a cooperative mechanism: the interaction of the anion with the hydroxyl groups of the AGU leads to H-bond disruption and the development of a negative charge on cellulose.…”

“…The development of new, advanced, environmentally friendly solvents for cellulose dissolution and subsequent regeneration rests on a clear understanding of both mechanisms. The complex interplay between H-bonding, ionization effects, and hydrophobic interactions is crucial to control dissolution, regeneration, gelation, and related phenomena [40]. As shown above, cellulose dissolution mechanism has been investigated in detail in recent years [10,40,70,81,[89][90][91][92][93][94][95][96][97][98][99][100][101].…”

The use of aminated cotton fibers as an unconventional sorbent to remove anionic dyes from aqueous solutions

“…At high pH value, the functional groups of sorbents (-OH, -NH 2 ) can be deprotonated, as a result of which the sorbent gains a negative charge (Lindman et al 2017;Pan et al 2019) and this inhibits the binding process of anionic dyes. At high pH, very low sorption efficiency of anionic dyes on CFs and ACFs may also result from competition of dyes with OHions (Jóźwiak et al 2020).…”