3.6.1. Contact Angle Analysis

The contact angle of the water droplets on the surface of disks prepared by compacting ITR, FD ITR, as well as the ITR–OXA, ITR–SUC and ITR–TER cocrystals, was measured to estimate the wettability of these samples. The photos taken during this experiment showed that the shape of the water droplets remained spherical on the surface of all the disks (Figure 10), highlighting the hydrophobicity of these materials.

**Figure 10.** Representative images of water droplets on the surface of disks and contact angles of: (**a**) crystalline ITR, (**b**) freeze dried ITR (FD ITR), (**c**) the ITR–OXA cocrystal, (**d**), the ITR–SUC cocrystal and (**e**) the ITR–TER cocrystal.

The contact angle values of the samples were similar (Table 2), with ITR–SUC and ITR–TER showing the lowest and the highest values, respectively. The values did not change significantly after 10 min of evaluation, in comparison to the initial values, indicating that the prolonged contact of the disks with water droplets had no e ffect on their wettability. These results indicated that the samples investigated, regardless of the solid-state form, had poor wettability, as the values of the contact angle were greater than 90◦ [36].


**Table 2.** Contact angle of a water droplet at the start and end of the measurement as well as the statistical analysis indicating no di fference between the initial and final values.

**\*)** After 10 min of droplet deposition.

**(**
