Figure 3.
Dark field optical microscopy images of precursors cast on glass slides (from 2 wt% CNC suspensions in 0.2 M SnCl4 in ethanol or water): (a) ethanolic suspension SnCl4/EtOH/CNC, (b) aqueous suspension containing acid: SnCl4/H2O/CNC/1M HCl, (c) aqueous suspension SnCl4/H2O/CNC after 1 h stirring and (d) aqueous suspension SnCl4/CNC/H2O after overnight stirring. The image (d) does not show any contrast, which indicates film homogeneity and absence of macroscopic aggregates. Scale bars: 0.2 mm.