1 research outputs found
Liquid Crystalline Phase Behavior and Sol–Gel Transition in Aqueous Halloysite Nanotube Dispersions
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