Lovis 2000 m me rolling ball viscometer

The viscosity of the 0.1 wt% model particle suspension in water was measured using the Lovis 2000 M/ME rolling ball viscometer (Anton Paar, Graz, Austria) at 20 °C.

A total of five different natural deep eutectic solvents (NADES; Table 1) were prepared using the standard heating and stirring method [23 (link)]. For this purpose, the components of the desired NADES were weighed into a round bottomed flask at the selected molar ratio (Table 1), and stirred over a water bath for at least 30 min. To reduce viscosity and facilitate handling, the prepared solvents were diluted further with 25% ultrapure water before use (NADES/water, 75%:25% w:w).
The densities (ρ, kg m⁻³) of these mixtures (NADES/water, 75%:25% w:w) were determined in the temperature range between 5 °C and 60 °C (278.15–333.15 K), in increments of 5 °C at an ambient pressure of 0.1 MPa using a DMA 5000 M vibrating tube densimeter (Anton Paar, Graz, Austria). The set temperatures were stable within the interval ± 0.005 °C, while the repeatability of the measurements was within ±5 × 10⁻³ kg m⁻³.
In addition, the dynamic viscosities (η, mPa·s) were measured in the same temperature range (from 5 °C to 60 °C) using a Lovis 2000 M/ME rolling-ball viscometer (Anton Paar, Austria). The diameter of the capillary used was 1.8 mm and was chosen according to the optimal run time of the measurements. Gilded rolling-balls were used to avoid corrosion of the rolling balls. The capillary was calibrated with the viscosity standard before use.