SEM observation of light control liquid crystal composite films

The structures of polymer networks in light control liquid crystal composite films (LCLCFs) were examined by Scanning Electron Microscope (SEM) observation. Normal mode and reverse mode LCLCFs were used for this research. Samples of the contact surface of the LCLCFs with the electrode substrate and its cross section were prepared. SEM images of the surface and cross-section of the normal mode LCLCFs showed that the liquid crystal material is uniformly dispersed within the polymer network. On the other hand, the liquid crystalline material in the reverse mode LCLCFs with a perpendicular alignment was mostly located near the electrode film, and the layer of polymer network was located in the middle region of the LCLCF. In other words, the reverse mode LCLCFs had a structure in which a polymer network-liquid crystal layer, a polymer layer, and a polymer network-liquid crystal layer are laminated. This difference is caused by the interaction between the electrode substrate surface and the polymer network obtained by the photo radical polymerization. In the reverse mode LCLCFs, the amount of polymer network adhered to the electrode substrate is smaller than in the normal mode LCLCFs. Therefore, the adhesion between the reverse mode LCLCFs and the electrode substrate is weaker when compared to the normal mode LCLCFs.