Dynamic heterogeneity in swollen nematic liquid crystal polymer near liquid-glass and sol-gel transition observed by the novel fluctuation microscopy

Conventional optical microscopes visualize static inhomogeneities such as orientation, concentration, and density within a material. On the other hand, our newly developed fluctuation microscope is a new microscope that directly visualizes the distribution of dynamics within a material as "dynamic inhomogeneity" as a two-dimensional image. We mixed liquid crystal molecule E44 and mesogen molecule with acrylate groups A6OCB and UV-polymerized them in a liquid crystal alignment cell to investigate the dynamics in the material near the liquid-glass transition point of the side-chain polymer swelling system, and near the sol-gel transition point by adding a very small amount of cross-linking agent. As a result, we succeeded in directly observing the characteristics of spontaneous dynamic heterogeneity formation. To investigate the correlation between the dynamic inhomogeneity generation and macroscopic viscoelasticity, simultaneous multi-frequency dynamic Young's modulus measurements were also performed. We found that when the temperature is lowered from the high-temperature nematic phase state, the remarkable dynamic heterogeneity appears in intermediate temperature range.