Chemistry Reference
In-Depth Information
molecules assembled into cubic, columnar, or smectic phases, depending on the rod
length and dendrimer generation (Fig. 11.26).
Jang et al. (2004) observed that ABA triblock copolymers composed of a docosyl
chain, a rigid aromatic segment, and a flexible PEO dendrimer assemble into a hex-
agonal columnar or body-centered cubic structure in the solid state for the first- and
second-generation dendrons, respectively (Fig. 11.27).
In aqueous media, they assemble into spherical capsules capable of
encapsulating Nile Red with remarkably low CMC values (2
10
27
M for G1
and 3
10
28
M for G2). Similarly, the size of the aggregate derived from a
related dendron-rod-dendron copolymer, composed of a phenylene vinylene
rod capped on each end by amphiphilic polyether dendrons, could be tuned in
the melt state by modifying the generation level of the dendron (Fig. 11.28; Lee
et al. 2002).
Presumably, at higher generations the increased bulk of the dendrons sterically
impedes aggregation, resulting in smaller aggregate structures.
Figure 11.26 (a) Chemical structures of rod-dendron and dendron-rod-dendron hybrids.
(b) Representations of the supramolecular organizations obtained from rod-dendron and
dendron-rod-dendron molecules. Reprinted from Lecommandoux et al. (2003). Copyright
2003 Wiley-VCH Verlag GmbH & Co. KGaA.
