Preparation and characterization of non-solvent halloysite nanotubes nanofluids

• Halloysite nanofluids were successfully synthesized through ion exchange approach.
• The morphology, dispersion, rheological behavior, as well as thermal stability of halloysite nanofluids were investigated.
• The halloysite nanofluids exhibited liquid-like behavior above 80°C without solvent.

In this paper, a novel type of clay mineral (halloysite) nanofluids was successfully synthesized through surface hydroxylated treatment and then tertiary amine and sulfonate anions. The halloysite (Hal) exhibits liquid-like behavior in the absence of solvent above 80 °C while it is a gel-like stickum at room temperature. Moreover, the morphology, rheological behavior, thermal and dispersion properties of the resultant Hal nanofluids were systematically characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray (EDX) analysis, X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), UV–Vis transmission spectra and rheological test. Rheological test results show that viscoelasticity (solid-like to liquid-like transition) of Hal nanofluids were regulated by temperature variation. The unique properties of the Hal nanofluids have made this material promising in the applications as rheological additives in industrial paints and polymer processing aids fields.