Ionic liquid interactions with cellulose and the effect of water

Abstract

Abstract Ionic Liquids (ILs) have been used to address issues such as recyclability, cost-effectiveness, and tailored thermophysical properties. This is most relevant to recent efforts directed at dissolving cellulose for filament spinning and bioproduct development. Herein, we introduce a simple method to investigate how interactions between cellulose films (roughness, Rh = 37 nm) and ILs specifically 1-butyl-3-methylimidazolium acetate ([bmim][OAc]), 1-butyl-3-methylimidazolium chloride ([bmim][Cl]), 1-ethyl-3-methylimidazolium acetate ([emim][OAc]), and 1-ethyl-3-methylimidazolium chloride ([emim][Cl]), along with their water mixtures (0, 5, and 10 wt%) affect thermophysical properties relevant to cellulose dissolution (surface tension, γ; contact angle, θ; diffusivities, D; and bulk density, ρ) at 363.15 K and 0.1 MPa under argon and air atmospheres. Thermophysical properties relevant to cellulose dissolution were measured at 363.15 K and 0.1 MPa under argon (surface tension, γ, contact angle, θ), and air (diffusivities, D and bulk density, ρ ) atmospheres to reveal the effect of the IL counter ions on the involved interactions with water. In general, water increased γ, θ , but reduced D , which supports experimental observations indicating the detrimental effect of water on IL-cellulose interactions. The [emim] + cation (in [emim][OAc] and [emim][Cl]), produced a lower contact angle with cellulose while the interfacial properties ( γ, θ, D ) for ILs with the [OAc] − anion were marginally affected by water. By contrast, the two ILs carrying [Cl] − anions exhibited a significant reduction in D (from 11.7 $$\cdot {10}^{-13}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>·</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>13</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> to 2.9 $$\cdot {10}^{-13} {m}^{2}{s}^{-1}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mrow> <mml:mo>·</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>13</mml:mn> </mml:mrow> </mml:msup> <mml:msup> <mml:mrow> <mml:mi>m</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msup> <mml:msup> <mml:mrow> <mml:mi>s</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> ) in the cation shift from [emim] + to [bmim] + at 363.15 K and 0.1 MPa, with 0% water content. Overall, we present a methodical approach rooted in experimental and theoretical approaches to facilitate our understanding of ionic liquids (ILs), especially within the domain of bioprocessing. Graphical Abstract

Topics & Concepts