Liquid Crystalline Phase Behavior and Sol鈥揋el Transition in Aqueous Halloysite Nanotube Dispersions

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• 作者：Zhiqiang Luo ; Hongzan Song ; Xiaorui Feng ; Mingtao Run ; Huanhuan Cui ; Licun Wu ; Jungang Gao ; Zhigang Wang
• 刊名：Langmuir
• 出版年：2013
• 出版时间：October 8, 2013
• 年：2013
• 卷：29
• 期：40
• 页码：12358-12366
• 全文大小：540K
• 年卷期：v.29,no.40(October 8, 2013)
• ISSN：1520-5827

文摘

The liquid crystalline phase behavior and sol鈥揼el transition in halloysite nanotubes (HNTs) aqueous dispersions have been investigated by applying polarized optical microscopy (POM), macroscopic observation, rheometer, small-angle X-ray scattering, scanning electron microscopy, and transmission electron microscopy. The liquid crystalline phase starts to form at the HNT concentration of 1 wt %, and a full liquid crystalline phase forms at the HNT concentration of 25 wt % as observed by POM and macroscopic observation. Rheological measurements indicate a typical shear flow behavior for the HNT aqueous dispersions with concentrations above 20 wt % and further confirm that the sol鈥揼el transition occurs at the HNT concentration of 37 wt %. Furthermore, the HNT aqueous dispersions exhibit pH-induced gelation with more intense birefringence when hydrochloric acid (HCl) is added. The above findings shed light on the phase behaviors of diversely topological HNTs and lay the foundation for fabrication of the long-range ordered nano-objects.