## 3 Results and Discussion
### Phase Separation and Structural Transformation of Polymer Blends at the Nanoscale  
Phase separation and the structural transformation behaviors of PS\({}^{1}\)/PVA blends confined in AAO\({}^{2}\) nanochannels are experimentally investigated herein. The effects of domain size and the mass ratios of PS\({}^{1}\)/PVA blends were investigated to clarify characteristic behaviors confined in the AAO\({}^{2}\) template, which influence the obtained morphologies of PS\({}^{1}\) nanostructures. Figure 5a,A and b,B show the SEM images of the cross-sectional PS\({}^{1}\)/PVA blends prepared by the advanced high-shear process. PVA dispersed phases with the domain size in the range of nanodomain and microdomain were prepared with the difference in PVA mass ratios of 10 and 30 wt% respectively. In the case of PS\({}^{1}\)/PVA (90/10 wt%) blend, PVA nanodomain was formed having a diameter in the range of 10-30 nm. For the PS\({}^{1}\)/PVA (70/30 wt%) blend, PVA microdomain was produced showing the smallest and average diameters of 300 nm and of 30 \(\upmu\)m, respectively. Figure 5c,C presents the mapping image of the ATR of the PS\({}^{1}\)/PVA film precursors. These results indicate that the uniform dispersion of the PVA in the PS\({}^{1}\) matrix was able to be prepared by using the high-shear process. However, the non-uniform area indicated signal distortion due to scattering of Infrared radiation (IR). Figure 4: Differential scanning calorimetry (DSC) thermograms of polymer films and nanostructures of (**a**) PS\({}^{1}\) and (**b**) PS\({}^{2}\). Figure 6A illustrates the top view images of PS1-VANs surface morphologies produced by thermal nanoimprint process. The obtained smooth surface of the PS1-VANs can be prepared using the neat PS1 film precursors. PS1-VAPNs can be produced using the PS1/PVA (90/10 wt%) precursor films followed by the selective removal of PVA segment as shown in Figure 6B,b. In the case of the PVA microdomain, the PS1-VANs with the nanopepapods-like form was replicated consisting of nanorods and nanospheres (See Figure 6C,c). The microholes on the imprinted film surface were observed because of the removal of the PVA segment. Transformation of PS1 nanostructures from nanocolumns into the nanorods and the nanospheres was induced by the Rayleigh instability due to the interfacial interaction of PS1 and PVA. The reduction of dimensionality from 1D into 0D is the intention of decreasing the surface energy of the system. In this experiment, the influence of imprinting conditions (temperature and time) were investigated to clarify the phase separation and structural transformation behaviors of the polymer nanostructures confined in AAO2 templates. Figure 5: Surface morphologies and surface chemical analysis of PS1/PVA blends; (**a,b**) SEM images of PS1/PVA (70/30 wt%), (**A,B**) SEM images of PS1/PVA (90/10 wt%), (**c**) ATR mapping of PS1/PVA (70/30 wt%) and (**C**) ATR mapping of PS1/PVA (90/10 wt%). Figure 6: Surface morphologies of (**A,a**) PS1—VANs (**B,b**) PS1—VAPNs and (**C,c**) PS1 nanopepods. Formation of the porous PS\({}^{1}\) nanostructured surfaces was able to be generated by the surface-induced phase separation of the PS\({}^{1}\)/PVA (90/10 wt%) blend in AAO\({}^{2}\) templates. Figure 7a-d illustrates the influence of the imprinting temperatures (120-180 \({}^{\circ}\)C) on the formation of pores on the nanostructured surfaces of PS\({}^{1}\). The visible pores were able to be imaged at the imprinting temperature at 180 \({}^{\circ}\)C. At this temperature, the formation of nanopores was caused by; (1) the flowability of PVA at melting state (\(T_{m}=161\)\({}^{\circ}\)C) and (2) the surface-induced phase separation due to the affinity of the hydrogen bond between AAO and PVA. Interfacial interaction between PVA-AAO\({}^{2}\) also promotes the coarsening behavior owing to the hydrogen bond. Therefore, the PVA droplets in the PS\({}^{1}\) matrix were formed on the pore wall of the AAO\({}^{2}\) template.