Litesizer 500 device

The electrophoretic light-scattering
measurements were performed on a Litesizer 500 device (Anton Paar)
using a 40 mW semiconductor laser operating at a 658 nm wavelength.
The samples were prepared via the following procedure. A 1.8 mL amount
of IL solutions of various concentrations was mixed with 0.2 mL of
h-HNT dispersion of 100 mg/L particle dose. The samples were allowed
to rest for 2 h at room temperature before measuring the electrophoretic
mobilities, which occurred after a 1 min equilibration time in the
device. The measurements were performed in 700 μL omega-shaped
plastic cuvettes (Anton Paar). The reported data are the average of
the results of five individual measurements. In all cases, the obtained
electrophoretic mobility (u) data were converted
to zeta potentials (ζ) with the Smoluchowski equation^{60 (link)} where η is the dynamic viscosity, ε
is the dielectric constant of the medium, and ε₀ is
the permittivity of the vacuum. The charge density of the particles
(σ) at the slip plane was determined with the Debye–Hückel
model^{61 (link)} where κ is the inverse
Debye length.^{60 (link)}

Hydrodynamic diameter (D_h) and intensity-weighted size distribution of the droplets in the formulations were analyzed by DLS using Litesizer 500 device (Anton Paar GmbH, Graz, Austria). The formulations were taken from the previous experiment and poured carefully into a quartz cell (Hellma Analytics, Müllheim, Germany) to avoid air bubbles. The measurements were performed at a light wavelength of 658 nm, a detection angle of 175° (backscattering), and the temperature was set to 25 °C. D_h and the broadness of the intensity size distribution, called the polydispersity index (PDI), were derived from the intensity curve fitting by applying the autocorrelation function using Kalliope Software (Anton Paar GmbH).

The size distribution and zeta potential of the IBs used in this study were analyzed with a Litesizer™ 500 device (Anton Paar, Graz, Austria). Samples were resuspened in ultrapure water and were treated with a Labsonic^®M sonicator for 1 min, with a 0.5 pulse regime at 40% amplitude. Fresh suspensions were always prepared prior analysis and transferred to single use cuvettes for dynamic light scattering (DLS) measurements, or alternatively, to omega cuvettes (Anton Paar, Graz, Austria) for the zeta potential measurements. Samples were analyzed in triplicates, averaging 30 single measurements.