Dissolution of cellulose in aqueous NaOH/urea solution: role of urea

Urea can improve the solubility and stability of cellulose in aqueous alkali solution, while its role has not come to a conclusion. To reveal the role of urea in solution, NMR was introduced to investigate the interaction between urea and the other components in solution. Results from chemical shift...

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Bibliographic Details
Published in:Cellulose (London) 2014, Vol.21 (3), p.1183-1192
Main Authors: Xiong, Bi, Zhao, Pingping, Hu, Kai, Zhang, Lina, Cheng, Gongzhen
Format: Article
Language:English
Subjects:
Bioorganic Chemistry
Cellulose
Ceramics
Chemistry
Chemistry and Materials Science
Composites
Dissolution
Glass
hydrogen bonding
Hydrogen bonds
hydrophobic bonding
Hydrophobicity
Hydroxyl groups
Natural Materials
NMR
Nuclear magnetic resonance
nuclear magnetic resonance spectroscopy
Organic Chemistry
Original Paper
Physical Chemistry
Polymer Sciences
Self-assembly
sodium
Sodium hydroxide
solubility
Sustainable Development
urea
Ureas
Van der Waals forces
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Summary:Urea can improve the solubility and stability of cellulose in aqueous alkali solution, while its role has not come to a conclusion. To reveal the role of urea in solution, NMR was introduced to investigate the interaction between urea and the other components in solution. Results from chemical shifts and longitudinal relaxation times show that: (1) urea has no strong direct interaction with cellulose as well as NaOH; (2) urea does not have much influence on the structural dynamics of water. Urea may play its role through van der Waals force. It may accumulate on the cellulose hydrophobic region to prevent dissolved cellulose molecules from re-gathering. The driving force for the self-assembly of cellulose and urea molecules might be hydrophobic interaction. In the process of cellulose dissolution, OH⁻ breaks the hydrogen bonds, Na⁺ hydrations stabilize the hydrophilic hydroxyl groups and urea stabilizes the hydrophobic part of cellulose.
ISSN:0969-0239
1572-882X
DOI:10.1007/s10570-014-0221-7