Liquid Crystalline Assembly of Rod–Coil Molecules - Liquid Crystalline Functional Assemblies and Their Supramolecular Structures - page 69

Fig. 4 GPC traces of rod-coil copolymer ( 7 ) and macromolecular object. Reprinted with
permission from [40-42]. © 2001 American Association for the Advancement of Science

of the strips suggested that the supramolecular structures could be bilayer
lamellar structures.
Incorporation of a rigid wedge-shaped building block into a diblock mo-
lecular architecture gives rise to a novel class of self-assembling systems
consisting of a rigid wedge and a flexible coil because the molecule shares
certain general characteristics of both dendrons and block copolymers. Lee
et al. reported the self-assembling behavior of wedge-coil diblock molecules
consistingofarigidwedgeandaflexiblePEOcoilinthemeltstate[45].All
of the molecules had a thermotropic liquid-crystalline structure after melt-
ing. The wide-angle X-ray diffraction patterns of all the molecules in the melt
state are characterized by a diffuse scattering, which confirms their liquid-
crystalline nature. However, a significant structural variation in the melt state
was observed as the length of the PEO segment was varied, as evidenced by
optical microscopic textures and small-angle X-ray diffraction patterns. The
variation in the supramolecular structure can be rationalized by consider-
ing the microphase separation between the dissimilar parts of the molecule
and the space-filling requirement of the flexible PEO chains (Fig. 5). The
molecules based on a short PEO chain can be packed with a radial arrange-
ment to fill the space efficiently, which results in a spherical supramolecular
structure. Increasing the length of the PEO chain results in more space for