Liquid Crystalline Blue Phases - Liquid Crystalline Functional Assemblies and Their Supramolecular Structures - page 113

Fig. 15 Chemical structures of the monomer and twin dimer, and schematic represen-
tation of molecular arrangement in the mixture of the monomer and twin dimer in the
novel smectic blue phase, SmBPiso [39]
rection as in TGB phases but also in two spatial directions [37]. Recently
another geometrical model based on minimal surfaces has also been pro-
posed [38] (Fig. 14). A novel smectic blue phase with spherical symmetry has
been found in a two-component mixture containing a chiral monomer and its
twin containing two repeat units of the first molecule connected by a linear
hydrocarbon spacer. The anomalous softening of elasticity due to a strong re-
duction in entropy caused by mixing the monomer and the twin permits the
seamless coexistence of these two competing liquid crystal orders. The new
phase spontaneously exhibits an optically isotropic but uniformly iridescent
color and automatically acquires spherical symmetry, so that the associated
photonic band gap maintains the same symmetry despite the local liquid
crystalline order [39] (Fig. 15).