The PMPs when doped lost their ability to rotate the polarized light (Figure 1) but improved their bending capabilities and mechanical properties (Figure 2). In fact the doped material could bend more as compared with control when irradiated with laser light (Figure 1 A). Furthermore, the ZnO nanoparticles could improve the material ability to store energy indicating that the sample had higher strength as compared to control (Figure 1 B).
Figure 1 – PMP observed using polarized microscopy Azo-LC-PMP (A, B) and doped PMP (C, D) samples tilted of 45 degrees (A, C) or parallel to one of the two polarizers (B, D).
Figure 2 – Comparison between the maximum bending (A) and Storage Modulus (B) of Azo-LC-PMP and ZnO doped AZO-LC-PMP films. The graphs show the increased efficiency of the doped PMPs in terms of bending and Storage modulus of the two formulations.
Interestingly, such doped material could self-vibrate (Figure 3) when stimulated with laser light at 457 nm even if the nematic configuration was apparently disturbed by the nanoparticles.
Figure 3 – Self-vibrating Zno-Doped PMP