Figure 4: Influence of the TBAB concentration on the photo-induced effect.
From: Spatially and temporally reconfigurable assembly of colloidal crystals
Images are acquired 150 s after illumination and the initial colloid volume fraction is 0.05. For these colloids, the particle zeta potential is a known function of TBAB concentration. (a–c) Images show PMMA colloid migration away from the illuminated region, thereby generating a void region of low colloid concentration. (d–f) Images show PMMA colloid migration towards the illuminated region, thereby leading to concentration and assembly. Scale bar, 5 μm. (g) For TBAB concentrations under 7.5 μM, ϕ decreases from its initial volume fraction, indicating depletion of particles within the region of interest. Above 7.5 μM TBAB, the volume fraction increases monotonically to a higher final volume fraction. (h) Final volume fraction values are extracted from g and plotted against their TBAB concentrations. There is a distinct transition between 7.5 and 8.75 μM TBAB; depletion is observed below this transition and assembly is observed above. The error bars indicate s.d.
