Abstract
We have identified cellulose solvents, comprised of binary mixtures of molecular solvents and ionic liquids that rapidly dissolve cellulose to high concentration and show upper-critical solution temperature (UCST)-like thermodynamic behaviour - upon cooling and micro phase-separation to roughly spherical microparticle particle-gel mixtures. This is a result of an entropy-dominant process, controllable by changing temperature, with an overall exothermic regeneration step. However, the initial dissolution of cellulose in this system, from the majority cellulose I allomorph upon increasing temperature, is also exothermic. The mixtures essentially act as ‘thermo-switchable’ gels. Upon initial dissolution and cooling, micro-scaled spherical particles are formed, the formation onset and size of which are dependent on the presence of traces of water. Wide-angle X-ray scattering (WAXS) and 13C cross-polarisation magic-angle spinning (CP-MAS) NMR spectroscopy have identified that the cellulose micro phase-separates with no remaining cellulose I allomorph and eventually forms a proportion of the cellulose II allomorph after water washing and drying. The rheological properties of these solutions demonstrate the possibility of a new type of cellulose processing, whereby morphology can be influenced by changing temperature.
Original language | English |
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Article number | e202100635 |
Number of pages | 13 |
Journal | ChemPhysChem |
Volume | 23 |
Issue number | 7 |
Early online date | 25 Feb 2022 |
DOIs | |
Publication status | Published - 5 Apr 2022 |
MoE publication type | A1 Journal article-refereed |
Keywords
- cellulose regeneration
- ionic liquids
- renewable resources
- spherulite
- UCST
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OtaNano - Nanomicroscopy Center
Seitsonen, J. (Manager) & Rissanen, A. (Other)
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