Fig. 4: Microscopic morphology and topography of films prepared with C2, C8 and C12 biobased optical ionogels.

a–c POM images and schematic representation of the LC director profiles of the droplets found in, respectively, C2, C8 and C12 films formed on top of glass slides. The red arrows indicate examples of radial droplets, the orange arrows indicate examples of escaped radial droplets, the purple arrows indicate examples of twisted radial droplets, and the green arrows indicate examples of axial droplets, where the droplet pole is perpendicular to the field of view. d–f Corresponding BF microscopy images of the films in (a–c). The scale bar in the optical microscopy images represents 50 µm. g–i Size distribution of droplets found in C2, C8 and C12 films, respectively. The histograms, the average and the standard deviation diameters were calculated for a large population of droplets (at least 1300 droplets) measured in at least 8 different regions of interest (ROI) of BF images of at least 2 independent films (C2: n = 2 films, 8 ROIs, total 1699 droplets; C8: n = 3 films, 9 ROIs, total 1323 droplets; C12: n = 7 films, 9 ROIs; total 2440 droplets). Polydispersity Index (PDI) was calculated as the ratio between the diameter standard deviation and the average diameter. j–l Atomic force microscopy (AFM) images (height retrace mode) showing the topography of the films’ surface and representative droplets (droplets with the most frequent diameter) found in each formulation (C2: 4 µm; C8: 10 µm; C12: 20 µm, according to the size distribution histograms in (g–i).