Molecular weight dependence of hysteresis in electro-optical switching of (polymer/liquid crystal) composite systems

The relationship between molecular weight (Mw) of matrix polymer and hysteresis in electro-optical switching was investigated for the poly(methyl methacrylate)/liquid crystal (PMMA/E8) composite systems. The size of the E8 domains in the (PMMA/E8) composite system was larger for the case of low Mw PMMA than the case of high Mw PMMA. This result can be explained by the magnitude of diffusion velocity depending on the Mw of PMMA. It was revealed that the electro-optical switching hysteresis of the high Mw-PMMA/E8 composite system decreased remarkably compared with the low Mw composite systems. This phenomenon might be explained on the basis of the different compatibility between PMMA and E8, which was directly dependent on the Mw of PMMA.