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into a 3D hexagonal close-packed structure (
P
6
3
mmc
space group symme-
try) in the melt state, confirmed by optical polarized microscopy and X-ray
diffraction measurements [82]. Cross-linking of
22
under UV irradiation of
254 nm in a liquid crystalline phase under nitrogen atmosphere for several
hours resulted in the formation of a completely soluble macromolecule. GPC
traces showed that the molecular weight appeared to be 270 kDa, with a nar-
row molecular weight distribution after polymerization. Small-angle X-ray
scattering revealed several reflections corresponding to a 3D hexagonal lat-
tice with essentially the same lattice constants as those of the coil-rod-coil
molecule, indicative of the preservation of the ordered symmetry and the di-
mensions of the discrete objects after polymerization. On the basis of these
lattice constants and measured density, the number of constituent units in
each object was estimated to be approximately 112. The 3D hexagonal close-
packed structure was observed to recover after isolation from the solutions
and transform into an isotropic liquid in the bulk state in a reversible way,
suggesting that the macromolecular objects are shape-persistent in solution
as well as being an isotropic liquid phase of the bulk (Fig. 14).
/
Fig. 14
Hexagonal close-packed liquid crystalline structure of the object and its trans-
formation in to an isotropic liquid state
In contrast to linear coil, the triblock molecule
23
, consisting of bis(penta-
ethylene glycol) dendrons as coil segments at both ends of the rod with
same rod building block, self-organizes into 2D columnar and 3D bicon-
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