Self-Assembly of Unfunctionalized Nanoparticles in Crystallization of Liquid Crystal Trimers

The crystallization of liquid crystal (LC) trimer-nanoparticle blends resulted in the formation of striped patterns in the crystals. The stripes were initially blurry but became sharper in the nematic LCs formed with heating. When the striped patterns began to collapse, many micron-scale colloidal particles were found out. Both the colloidal particles and stripes disappeared after an increase of 1.0-1.5 °C beyond the temperature at which the colloidal particles appeared. These results suggested that the stripes consisted of the colloidal particles. The distance between stripes depended on the shapes and sizes of the colloidal particles and the cooling rate during the crystallization. There were two melting peaks on the DSC chart of the LC trimer-nanoparticle blends. The two peaks corresponded to the melting of the LC trimers and the disappearance of the colloidal particles, respectively. On the basis of these data, we think that the colloidal particles are composed of hybrid structures in which LC trimers enclose the nanoparticles. The relationship between the striped patterns and the colloidal particles is discussed.