Achiral flexible liquid crystal trimers exhibiting gyroid-like surfaces in chiral conglomerate phases

Abstract

Chiral conglomerate phases have attracted much attention not only for the spontaneous mirror symmetry breaking but also for their nanostructures. We investigated both surface and bulk structures of a homologues series of an achiral liquid crystal trimer I-(n,m) exhibiting soft crystalline chiral conglomerate phases by atomic force microscopy (AFM) and scanning electron microscopy (SEM). The trimers were found to form bicontinuous networks. In particular, trimer I-(9,9) exhibited a single gyroid-like surface accompanying periodic distribution of dimples with a size of about 100 nm. It showed a sponge-like structure in the bulk of the material. The twist conformation of the flexible trimer I-(n,m) can cause layer deformation, which produces bicontinuous networks exhibiting optical activity.