Dissolution of cellulose in aqueous NaOH/urea solution: role of urea
Dissolution of cellulose in aqueous NaOH/urea solution: role of urea
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DOI：
10.1007/s10570-014-0221-7
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发表时间：
2014-06-01
期刊：
影响因子：
5.7
通讯作者：
Cheng, Gongzhen
中科院分区：
文献类型：
--
作者：
Xiong, Bi;Zhao, Pingping;Cheng, Gongzhen
尿素可以提高纤维素在碱溶液中的溶解度和稳定性，但其作用还没有定论。为了揭示尿素在溶液中的作用，采用核磁共振技术研究了尿素与溶液中其他组分的相互作用。化学位移和纵向弛豫时间的结果表明：（1）尿素与纤维素和NaOH没有强的直接相互作用;（2）尿素对水的结构动力学没有太大的影响。尿素可能通过货车范德华力发挥作用。它可以积聚在纤维素疏水区，以防止溶解的纤维素分子重新聚集。纤维素和尿素分子自组装的驱动力可能是疏水相互作用。在纤维素溶解过程中，OH-破坏氢键，Na+水化稳定亲水羟基，尿素稳定纤维素的疏水部分。
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.