Liquid Crystalline Assembly of Rod–Coil Molecules - Liquid Crystalline Functional Assemblies and Their Supramolecular Structures - page 87

Fig. 16 Li + ion conduction for the complex of 26 in smectic A phase. Reprinted with
permission from [86]. © 2000 American Chemical Society

structure can be reorganized on cooling indicating that this transition is re-
versible.

3.4
Novel Rod-Coil Triblock Copolymers

Precise control of supramolecular objects requires the rational design of
molecular components, because the information determining their specific
assembly should be encoded in their molecular architecture. Lee and cowor-
kers reported on novel rod-coil molecules based on a hexa- p -phenylene rod
and PEO chains that are fused together into a macrocyclic ring [88, 89]. The
rod-coil macrocycle was observed to undergo double phase transitions in the
crystalline state and to form ordered mesophases at higher temperature, as
confirmed by differential scanning calorimetry. In the first crystalline state,
27 self-assembles into infinitely long ribbon-like 1D aggregates with uniform
width and thickness. The cyclic geometry of the coil attached to one side of
the rod would prohibit the 2D growth of a self-assembled structure. Instead,
the aromatic rod segments should be strongly driven to aggregate in one di-
mension to produce a laterally stacked bilayer through microphase separation
between the rod and coil segments, and interactions. In the second crys-

talline state, the rod segments of 27 self-assemble into discrete ribbon-like

π - π