Phase-separation of cellulose from ionic liquid upon cooling : preparation of microsized particles

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Xia , J , King , A W T , Kilpelainen , I & Aseyev , V 2021 , ' Phase-separation of cellulose from ionic liquid upon cooling : preparation of microsized particles ' , Cellulose , vol. 28 , no. 17 , pp. 10921-10938 . https://doi.org/10.1007/s10570-021-04230-w

Title: Phase-separation of cellulose from ionic liquid upon cooling : preparation of microsized particles
Author: Xia, Jingwen; King, Alistair W. T.; Kilpelainen, Ilkka; Aseyev, Vladimir
Contributor organization: Department of Chemistry
Doctoral Programme in Chemistry and Molecular Sciences
Synthesis and Analysis
Helsinki Institute of Sustainability Science (HELSUS)
Polymers
Date: 2021-11
Language: eng
Number of pages: 18
Belongs to series: Cellulose
ISSN: 0969-0239
DOI: https://doi.org/10.1007/s10570-021-04230-w
URI: http://hdl.handle.net/10138/336085
Abstract: Cellulose is an historical polymer, for which its processing possibilities have been limited by the absence of a melting point and insolubility in all non-derivatizing molecular solvents. More recently, ionic liquids (ILs) have been used for cellulose dissolution and regeneration, for example, in the development of textile fiber spinning processes. In some cases, organic electrolyte solutions (OESs), that are binary mixtures of an ionic liquid and a polar aprotic co-solvent, can show even better technical dissolution capacities for cellulose than the pure ILs. Herein we use OESs consisting of two tetraalkylphosphonium acetate ILs and dimethyl sulfoxide or gamma-valerolactone, as co-solvents. Cellulose can be first dissolved in these OESs at 120 degrees C and then regenerated, upon cooling, leading to micro and macro phase-separation. This phenomenon much resembles the upper-critical solution temperature (UCST) type thermodynamic transition. This observed UCST-like behavior of these systems allows for the controlled regeneration of cellulose into colloidal dispersions of spherical microscale particles (spherulites), with highly ordered shape and size. While this phenomenon has been reported for other IL and NMMO-based systems, the mechanisms and phase-behavior have not been well defined. The particles are obtained below the phase-separation temperature as a result of controlled multi-molecular association. The regeneration process is a consequence of multi-parameter interdependence, where the polymer characteristics, OES composition, temperature, cooling rate and time all play their roles. The influence of the experimental conditions, cellulose concentration and the effect of time on regeneration of cellulose in the form of preferential gel or particles is discussed.
Subject: Cellulose regeneration
Spherulite
UCST
Phosphonium acetate
SINGLE POLYSTYRENE CHAIN
METHYLMORPHOLINE-N-OXIDE
COIL-GLOBULE TRANSITION
THERMOREVERSIBLE GELS
X-RAY
DISSOLUTION
REGENERATION
CRYSTALLIZATION
SPHERULITES
MORPHOLOGY
116 Chemical sciences
Peer reviewed: Yes
Rights: cc_by
Usage restriction: openAccess
Self-archived version: publishedVersion


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