Factors Affecting the Nonsolvent-Induced Phase Separation of Cellulose from Ionic Liquid-Based Solutions

Abstract

In the present work, we report for the first time an in-depth study of the factors influencing porous cellulose film structure formation during the nonsolvent-induced phase separation (NIPS) process from biopolymer solutions in ionic liquid-based solvents. The length of the alkyl chain of the ionic liquid’s cation, the solvent/co-solvent ratio, and the type of the cellulose precursor used were found to have great influence both on cellulose solution formation and properties and to the NIPS process with water acting as nonsolvent. In the undiluted form, both studied ionic liquids proved to dissolve almost equally well the cellulose; however, due to differences in viscosities of the formed biopolymer solutions and due to differences in miscibility with water of the two ionic liquids, the used ionic liquid had a strong influence on the film’s porous structure formation. The use of increasing amounts of an aprotic co-solvent, here dimethylsulfoxide, improved biopolymer solubilization and also led to the formation of a more pronounced macroporous structure during the NIPS process. The cellulose type also affected the porous structure generation during the NIPS process: with the increase of the molecular weight of the precursor, the viscosity of the formed biopolymer solution increased and the tendency to generate macroporous structures decreased.

Cotton as Precursor for the Preparation of Porous Cellulose Adsorbers

“…The modified Langmuir model takes into account the influence of concentration of the solute in bulk solution on the desorption process. [ 39 ] For example, this model was successfully used at the evaluation of the adsorption properties against Pb 2+ of cellulose–boehemite films. [ 40 ] The modified Langmuir isotherms obtained with our experimental data are presented in Figure S2, Supporting Information.…”

Solution-Based Processing for Scaffold Fabrication in Tissue Engineering Applications: A Brief Review

“…They found that the gelation time and the properties of the hydrogels were influenced by the amount of the nonsolvent, silk concentration, and incubation temperature. Recently, Wittmar et al [ 66 ] studied for the first time the NIPS process starting from biopolymer solutions in ionic liquid-based solvents, with or without acetone as a co-solvent, to produce porous cellulose film structures. The results demonstrated that cellulose with a high polymerization degree generated more compact films under identical NIPS conditions, as Figure 4 shows.…”

“… Influence of the cellulose type on the porous film structure (cross-section of 8 wt % cellulose-based films) [ 66 ]. Reprint with permission from ACS.…”

Wood-Based Cellulose-Rich Ultrafiltration Membranes: Alkaline Coagulation Bath Introduction and Investigation of Its Effect over Membranes’ Performance

“…The steady interest towards ionic liquids (ILs) as cellulose and biomass solvent media is supported with such characteristics as their potential recyclability, low vapour pressure, and good chemical and thermal stability [20][21][22][23]. The challenges regarding ILs' high price and high viscosity can be mitigated successfully by the addition of a cosolvent [13,16,21,[24][25][26][27].…”