Liquid Crystalline Phase Behavior and Sol–Gel Transition in Aqueous Halloysite Nanotube Dispersions
writer：Zhiqiang Luo, Hongzan Song, Xiaorui Feng, Mingtao Run, Huanhuan Cui, Licun Wu, Jungang Gao, and Zhig
keywords：Liquid Crystalline ， Sol?Gel Transition
source：期刊
specific source：Langmuir, 2013, 29, 12358–12366
Issue time：2013年
The liquid crystalline phase behavior and sol?gel 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?gel 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.