Properties Originating from Microphase Separation

Azo BCs are one fascinating class of soft materials, showing a rich variety of microphase-separated nanostructures in films because the strongly bonded azo segments and the non-azo blocks are thermodynamically incompatible. As shown in Fig. 12.1, the microphase-separated morphologies can be controlled to be spheres, cylinders, or lamellae, depending on the length, chemical nature, architecture, and number of repeated units in each block (e.g., Thomas and Lescanec, 1994). 

When the azo block shows LC properties, the inherent mesogenic ordering might act on the thermodynamic process of microphase separation by SMCM. 

According to the molecular component of the azo BC, the wormlike domains with a width of 25 nm should be segregated by the azo blocks, leading to the disappearance of an LC texture after microphase separation because of the limited POM resolution. The novel wormlike nanostructures might be caused by the balance between microphase separation and LC self-assembly, which makes it different from the phase-segregated morphologies of BCs with weak molecular interactions (Yu et al., 2007b). 

---