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Revisiting the dissolution of cellulose in H3PO4(aq) through cryo-TEM, PTssNMR and DWS

Alves, Luís ; Medronho, Bruno LU ; Filipe, Alexandra ; Romano, Anabela ; Rasteiro, Maria G. ; Lindman, Björn LU ; Topgaard, Daniel LU ; Davidovich, Irina and Talmon, Yeshayahu (2021) In Carbohydrate Polymers 252.
Abstract

Cellulose can be dissolved in concentrated acidic aqueous solvents forming extremely viscous solutions, and, in some cases, liquid crystalline phases. In this work, the concentrated phosphoric acid aqueous solvent is revisited implementing a set of advanced techniques, such as cryo-transmission electronic microscopy (cryo-TEM), polarization transfer solid-state nuclear magnetic resonance (PTssNMR), and diffusing wave spectroscopy (DWS). Cryo-TEM images confirm that this solvent system is capable to efficiently dissolve cellulose. No cellulose particles, fibrils, or aggregates are visible. Conversely, PTssNMR revealed a dominant CP signal at 25 °C, characteristic of C-H bond reorientation with correlation time longer than 100 ns and/or... (More)

Cellulose can be dissolved in concentrated acidic aqueous solvents forming extremely viscous solutions, and, in some cases, liquid crystalline phases. In this work, the concentrated phosphoric acid aqueous solvent is revisited implementing a set of advanced techniques, such as cryo-transmission electronic microscopy (cryo-TEM), polarization transfer solid-state nuclear magnetic resonance (PTssNMR), and diffusing wave spectroscopy (DWS). Cryo-TEM images confirm that this solvent system is capable to efficiently dissolve cellulose. No cellulose particles, fibrils, or aggregates are visible. Conversely, PTssNMR revealed a dominant CP signal at 25 °C, characteristic of C-H bond reorientation with correlation time longer than 100 ns and/or order parameter above 0.5, which was ascribed to a transient gel-like network or an anisotropic liquid crystalline phase. Increasing the temperature leads to a gradual transition from CP to INEPT-dominant signal and a loss of birefringence in optical microscopy, suggesting an anisotropic-to-isotropic phase transition. Finally, an excellent agreement between optical microrheology and conventional mechanical rheometry was also obtained.

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author
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organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Anisotropy, Cellulose dissolution, cryo-TEM, DWS, Liquid crystalline phase, Phosphoric acid, PTssNMR
in
Carbohydrate Polymers
volume
252
article number
117122
publisher
Elsevier
external identifiers
  • scopus:85091946838
ISSN
0144-8617
DOI
10.1016/j.carbpol.2020.117122
language
English
LU publication?
yes
id
f96b7e48-a40b-488a-9703-c45041e23914
date added to LUP
2020-10-26 12:13:25
date last changed
2020-10-28 16:15:28
@article{f96b7e48-a40b-488a-9703-c45041e23914,
  abstract     = {<p>Cellulose can be dissolved in concentrated acidic aqueous solvents forming extremely viscous solutions, and, in some cases, liquid crystalline phases. In this work, the concentrated phosphoric acid aqueous solvent is revisited implementing a set of advanced techniques, such as cryo-transmission electronic microscopy (cryo-TEM), polarization transfer solid-state nuclear magnetic resonance (PTssNMR), and diffusing wave spectroscopy (DWS). Cryo-TEM images confirm that this solvent system is capable to efficiently dissolve cellulose. No cellulose particles, fibrils, or aggregates are visible. Conversely, PTssNMR revealed a dominant CP signal at 25 °C, characteristic of C-H bond reorientation with correlation time longer than 100 ns and/or order parameter above 0.5, which was ascribed to a transient gel-like network or an anisotropic liquid crystalline phase. Increasing the temperature leads to a gradual transition from CP to INEPT-dominant signal and a loss of birefringence in optical microscopy, suggesting an anisotropic-to-isotropic phase transition. Finally, an excellent agreement between optical microrheology and conventional mechanical rheometry was also obtained.</p>},
  author       = {Alves, Luís and Medronho, Bruno and Filipe, Alexandra and Romano, Anabela and Rasteiro, Maria G. and Lindman, Björn and Topgaard, Daniel and Davidovich, Irina and Talmon, Yeshayahu},
  issn         = {0144-8617},
  language     = {eng},
  month        = {01},
  publisher    = {Elsevier},
  series       = {Carbohydrate Polymers},
  title        = {Revisiting the dissolution of cellulose in H<sub>3</sub>PO<sub>4</sub>(aq) through cryo-TEM, PTssNMR and DWS},
  url          = {http://dx.doi.org/10.1016/j.carbpol.2020.117122},
  doi          = {10.1016/j.carbpol.2020.117122},
  volume       = {252},
  year         = {2021},
}