## 3 Results and Discussion
### Mesogen Orientation of PAz Films
#### 3.1.3. PAz Film with Top-Coated Amorphous Polymers  
Next, the surfaces of the PAz films (thickness: 100 nm) were covered with PBMA, P4 VP and PVP. PBMA was overlaid using cyclohexane and P4 VP and PVP with methanol, both of which are poor solvents for PAz. The thickness of the overlaid amorphous polymers was 100-200 nm. The coverage of the top surface of the PAz with the amorphous polymers was confirmed by static contact angle measurements using a water droplet. Table 2 lists the contact angles of the water droplets (\(\theta_{\mathrm{w}}\)) on various polymer surfaces. \(\theta_{\mathrm{w}}\) values from the literature are also shown in parentheses for comparison. The surface of the PAz was highly hydrophobic due to the homeotropic anchoring, where the alkyl tail was oriented toward the air. When the top surface was covered with the amorphous polymers, the resulting \(\theta_{\mathrm{w}}\) agreed well with the pure amorphous polymers, indicating that the top-coating was successfully performed. The PAz films covered with PBMA, P4 VP and PVP at room temperature consistently provided the same results as those for the glass substrate (see Section 3.1.2). The films covered with amorphous polymers indicated a random planar orientation state, whose typical domain size range was approximately some micrometers. Representative examples of the POM image are shown in Figure 3 for the PAz films covered with PBMA films 100 nm (a) and 400 nm (b) thick. Figure 4 shows the GI-SAXS data for the PAz film covered with PVP as an example. By covering the surface with the polymer film, the scattering spots became sharpened, indicating that the orientational disorder became more suppressed (compared with the data in Figure 2). A thicker topcoat film with a 400-nm thickness was also examined. The thickness of the topcoat layer did not significantly influence the results. \begin{table}
\begin{tabular}{c c} \hline
**Film** & **Contact Angle \(\theta_{\mathrm{w}}\) (c)** \\ \hline PAz & 104.6 \(\pm\) 0.3 (103.7 \(\pm\) 0.3 [24]) \\ PBMA & 97.8 \(\pm\) 0.2 (98.0 \(\pm\) 0.7 [19]) \\ P4 VP & 76.6 \(\pm\) 0.5 (70–75 [42]) \\ PVP & 34.6 \(\pm\) 1.7 (65.5 [43]) \\ PBMA on PAz & 98.2 \(\pm\) 0.3 \\ P4 VP on PAz & 75.6 \(\pm\) 0.8 \\ PVP on PAz & 37.8 \(\pm\) 0.7 \\ \hline \end{tabular}
\end{table} 
Table 2: Static contact angles of water droplets at room temperature. Figure 3: POM images of PAz of 100-nm thickness covered with PBMA films 100 nm (**a**) and 400 nm (**b**) thick. The three polymer layers (PBMA, P4 VP and PVP) on the top essentially gave the same anchoring effect, but small differences were observed when the PAz film was thickened to 400 nm. Figure 5 indicates the 2D GI-SAXS images of the PAz film covered with the three polymer layers. At room temperature, the X-ray images consistently gave the tilt layer structure ascribed to the smectic C phase, but the smectic layer with the PBMA topcoat indicated a more disordered orientation state, judging from the vague arc-scattering image (left) compared with the other two polymer topcoats. In the cases of P4 VP and PVP topcoats (middle and right), layer spacing was also observed in the out-of-plane direction (white arrow). This seems to show that P4 VP and PVP tend to induce homeotropically aligned mesogens partially in the contacting region with the polymer. We do not have clear explanations for the different characteristics between the PBMA and P4 VP or PVP at present. One plausible possibility is that the difference in \(T_{\mathrm{g}}\) can affect the anchoring behavior [44]. As the polarity of the polymers also differed, this was not the decisive factor to account for the present observations. Figure 4: GI-SAXS data for PAz film (thickness: 100 nm) covered with PVP (thickness: 100 nm) at room temperature (**a**) and 90 \({}^{\circ}\)C (**b**). In each part, left and right figures display 2D GI-SAXS patterns and 1D intensity profiles taken from the 2D data, respectively.