group was replaced by a benzoate derivative possessing a CF 3 a group at its terminus (molecule C in Figure 15.18). Thin films of this triblock copolymer were
shown to contain similar mushroom-shaped nano-aggregates, but with significantly smaller sizes, roughly ca. 20–23 molecules per aggregate. Heating these
films to 250
C, the temperature at which these materials form a thermotropic
liquid crystalline phase, for prolonged periods (20 h) under inert atmosphere led to
the fixation of these aggregates by a crosslinking process via the olefinic sites in the
PB block. Interestingly, after thermal crosslinking the films were readily soluble in
organic solvents and GPC analysis confirmed the formation of macromolecular
objects that were the result of stitching together ca. 20 triblock copolymer molecules. The polydispersity values obtained from GPC were also very low, ca. 1.1.
Fig. 15.19. Schematic depiction of the packing of strip-like and
disk-like domains formed by the rod segments. (Reprinted with
permission from Macromolecules, 1997, 30, 2110. 8 1997
American Chemical Society [67].)
Fig. 15.20. TEM picture of the mushroomshaped aggregate (a) (inset shows a schematic
depiction of the aggregate) and of the nanoribbons (b). ((a) Reprinted with permission
from Macromolecules, 2000, 33, 3550. 8 2000
American Chemical Society [69], and (b) from
J. Am. Chem. Soc., 2001, 123, 4105. 8 2001
American Chemical Society [71].)
15.7 Rod–Coil Diblock Copolymers 505
shown to contain similar mushroom-shaped nano-aggregates, but with significantly smaller sizes, roughly ca. 20–23 molecules per aggregate. Heating these
films to 250
C, the temperature at which these materials form a thermotropic
liquid crystalline phase, for prolonged periods (20 h) under inert atmosphere led to
the fixation of these aggregates by a crosslinking process via the olefinic sites in the
PB block. Interestingly, after thermal crosslinking the films were readily soluble in
organic solvents and GPC analysis confirmed the formation of macromolecular
objects that were the result of stitching together ca. 20 triblock copolymer molecules. The polydispersity values obtained from GPC were also very low, ca. 1.1.
Fig. 15.19. Schematic depiction of the packing of strip-like and
disk-like domains formed by the rod segments. (Reprinted with
permission from Macromolecules, 1997, 30, 2110. 8 1997
American Chemical Society [67].)
Fig. 15.20. TEM picture of the mushroomshaped aggregate (a) (inset shows a schematic
depiction of the aggregate) and of the nanoribbons (b). ((a) Reprinted with permission
from Macromolecules, 2000, 33, 3550. 8 2000
American Chemical Society [69], and (b) from
J. Am. Chem. Soc., 2001, 123, 4105. 8 2001
American Chemical Society [71].)
15.7 Rod–Coil Diblock Copolymers 505