From Cellulose Dissolution and Regeneration to Added Value Applications — Synergism Between Molecular Understanding and Material Development

Abstract

Modern society is now demanding greener materials due to depleting fossil fuels and increasing environmental awareness. In the near future, industries will need to become more resource-conscious by making greater use of available renewable and sustainable raw materials. In this context, agro-forestry and related industries can indeed contribute to solve many resource challenges for society and suppliers in the near future. Thus, cellulose can be predicted to become an important resource for materials due to its abundance and versatility as a biopolymer. Cellulose is found in many different forms and applications. However, the dissolution and regeneration of cellulose are key and challenging aspects in many potential applications. This chapter is divided into two parts i achievements in the field of dissolution and regeneration of cellulose including solvents and underlying mechanisms of dissolution and ii state-of-the-art production of value-added materials and their applications including manmade textile fibers, hydrogels, aerogels, and all-cellulose composites, where the latter is given special attention.Keywords: Cellulose, dissolution and regeneration, fiber, hydrogels, all-cellulose composites . IntroductionCellulose was isolated for the first time by the French chemist "nselme Payen in [ ], who extracted it from green plants and reported its elemental composition four years later [ ].Cellulose is the main component of the cell wall in higher plants, typically combined with © 2015 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.lignin, hemicelluloses, pectins, proteins, and water. "part from higher plants, cellulose can be synthesized by bacteria or be found in algae and tunicates. This readily available and renewable biopolymer is widely used in many applications such as paper, textiles, membranes, or packaging [ ]. Cellulose is the most abundant and studied biorenewable material with an estimated annual production of . x t [ ]. "fter more than years of research into the sugar of the plant cell wall , consumers, industries, and governments are increasingly demanding products from renewable and sustainable resources that are biodegradable, nonpetroleum based, carbon neutral, and, at the same time, generating low environmental, animal/ human health and safety risks [ ].Regarding its basic structure, cellulose is a linear syndiotactic homopolymer composed of D-anhydroglucopyranose units "GU , that are connected by -glycosidic bonds Figure [ ]. The size of the cellulose molecules can be defined by the average degree of polymerization DP . The average molecular weight is estimated from the product of the DP and the molecular mass of a single "GU. Each "GU bears three hydroxyl groups one primary and two secondary moieties that represent more than % by weight , with t...

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

“…Moreover, the anti-parallel chain model enables the formation of inter-chain and inter-plane H-bonds [117]. Cellulose regeneration from its solutions is based on exchange of solvent molecules with non-solvent molecules (coagulant) which initiates the reformation of cellulose [119]. It requires principally the same steps as native cellulose I crystallization: (1) formation of mini-sheets by van der Waals forces, (2) association of these sheets by H-bonding into "mini-crystals", (3) convergence Cellulose regeneration from its solutions is based on exchange of solvent molecules with non-solvent molecules (coagulant) which initiates the reformation of cellulose [119].…”

“…Cellulose regeneration from its solutions is based on exchange of solvent molecules with non-solvent molecules (coagulant) which initiates the reformation of cellulose [119]. It requires principally the same steps as native cellulose I crystallization: (1) formation of mini-sheets by van der Waals forces, (2) association of these sheets by H-bonding into "mini-crystals", (3) convergence Cellulose regeneration from its solutions is based on exchange of solvent molecules with non-solvent molecules (coagulant) which initiates the reformation of cellulose [119]. It requires principally the same steps as native cellulose I crystallization: (1) formation of mini-sheets by van der Waals forces, (2) association of these sheets by H-bonding into "mini-crystals", (3) convergence of these crystals to form the larger crystalline or amorphous arrangements [102].…”

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

“…[119][120][121] Typically, regeneration involves the use of non-solvents, which, upon contact with the dissolved cellulose dope, induce the precipitation (coagulation) of cellulose. The kinetics of coagulation are essentially controlled by the relative diffusion velocities of solvent from the cellulose dope to the coagulation medium and the counterpart reverse process, diffusion of the non-solvent into the cellulose dope.…”

Properties and Structure of Cellulosic Membranes Obtained from Solutions in Ionic Liquids Coagulated in Primary Alcohols

“…Therefore, many systems capable of dissolving this polymer have been developed, including NaOH/CS 2 , DMSO/TBAF, LiCl/DMAc, and N 2 O 4 /DMF [6,7], which have disadvantages such as volatility, toxicity, or flammability. Another system used to dissolve cellulose is NMMO/H 2 O, which, unlike previously mentioned ones, is environmentally friendly and cost-effective [6].…”