Stability of inclusion complex formed by cellulose in NaOH/urea aqueous solution at low temperature.
Stability of inclusion complex formed by cellulose in NaOH/urea aqueous solution at low temperature.
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DOI：
10.1016/j.carbpol.2012.10.004
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发表时间：
2013-02
影响因子：
11.2
通讯作者：
Xingzhen Qin;A. Lu;J. Cai;Lina Zhang
中科院分区：
文献类型：
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作者：
Xingzhen Qin;A. Lu;J. Cai;Lina Zhang
纤维素在预冷至- 12°C的7wt% NaOH/12wt%尿素水溶液中溶解，这是纤维素、尿素和NaOH形成包合物（ICs）的结果。然而，这种纤维素溶液是亚稳定的，可以形成IC聚集体。本文采用动态光散射和静态光散射的方法研究了溶剂组成和温度对纤维素ic在NaOH/尿素水溶液体系中稳定性的影响。随着NaOH浓度的增加，纤维素ic在NaOH/尿素水溶液体系中的稳定性先增强后降低。尿素的加入略微提高了ic的稳定性。此外，还对溶剂组成进行了优化，以减少ic的聚集现象。在9wt% NaOH/13wt%尿素体系中，单个纤维素集成电路的比例提高到0.96，表明纤维素集成电路是一个稳定的、较好的分散体系。此外，温度对集成电路的稳定性有很大影响。在10℃下，9wt% NaOH/13wt%尿素体系中纤维素的分子量较低，约为7.6×104g/mol，且以单组分纤维素为主。本研究为NaOH/尿素水溶液中以单组分纤维素为主的稀纤维素提供了更好的表征途径。
Cellulose has been demonstrated to be dissolved in 7wt% NaOH/12wt% urea aqueous solution pre-cooled to −12°C, as a result of the formation of inclusion complexes (ICs) associated with cellulose, urea and NaOH. However, this cellulose solution is meta-stable, and IC aggregate could form. In this work, the influences of solvent composition and temperature on the stability of the cellulose ICs in NaOH/urea aqueous solvent system were investigated by dynamic and static light scattering. The stability of cellulose ICs in NaOH/urea aqueous solvent system was firstly enhanced and then lessened with NaOH concentration increasing. The addition of urea slightly enhanced the stability of ICs. Furthermore, the solvent composition had been optimized to reduce the aggregation phenomenon of ICs. The proportion of single cellulose ICs in 9wt% NaOH/13wt% urea system increased to 0.96, indicating a stable and better dispersion system of the cellulose ICs. Moreover, temperature exhibited great effect on the IC stability. The molecular weight of cellulose in 9wt% NaOH/13wt% urea system at 10°C reached a low value about 7.6×104g/mol and the single cellulose ICs were predominant species in this case. This work provided a better pathway to characterize the dilute cellulose in NaOH/urea aqueous solution, in which the single cellulose ICs were predominant species.