The liquid-crystalline properties and the phase transition behaviors of SMPU-OOBAm composites were investigated by POM. As we known, OOBA exhibits two crystalline forms, followed by smectic and nematic LC phases upon heating. Typical POM textures of OOBA upon heating are shown in Figure 8. At low temperatures, OOBA forms a stable crystalline phase (see Figure 8a). When the temperature increases to 112 °C, the colourful crystalline texture turns into a smectic LC phase (see Figure 8b). When the temperature continuously increases, the smectic LC texture converts to the nematic LC phase at 135 °C (see Figure 8c). As is known, an amorphous substance has no birefringence, and the field of vision is dark. The OOBA has good liquidity in the nematic phase. Thus, it is hard to get a whole continuous nematic texture at 135 °C. Therefore, the dark areas seen in Figure 8c resulted from either the isotropic phase of part of the OOBA or the amorphous substrate. When the temperature reaches 139 °C, the LC texture begins to disappear and the field of vision becomes dark (Figure 8d). This is the isotropic temperature of OOBA, which exactly corresponds to the exothermic peak on the DSC curve (see Figure 5a).