Three-state Structural Switching and Selective Molecular Interactions of Cylindrical Concentric Monodomain Liquid Crystal Elastomer

A cross-linked poly(acrylate) containing an ethynylhelicene (P)-pentamer was synthesized by radical polymerization between two horizontally aligned films with a parallel arrangement in trifluoromethylbenzene. The resulting liquid crystal elastomer swollen in bromobenzene showed the Maltese cross, which indicated a cylindrical concentric monodomain structure of the millimeter-order size as determined by polarized optical microscopy (POM) analysis. In toluene, a homogeneously bright POM image was obtained, which reversibly changed in intensity upon heating and cooling. Addition of an (M)-tetramer to the liquid crystal elastomer in toluene produced a hetero-double-helix exhibiting the Maltese cross, whose intensity did not change upon heating and cooling. The three states can be switched by addition and removal of an (M)-tetramer and solvents.