Coil-crystalline block

Keywords Coil-crystalline block copolymers Micelles in solution Light scattering Transmission electron microscopy Cross-linkable micelles... 

Vilgis T, Halperin A. Aggregation of coil-crystalline block copolymers equilibrium crystallization. Macromolecules... 

Figure 2. Structure of liquid crystalline block copolymers (LC-BCPs) (A) rod-coil diblock copolymer (B) rod-coil diblock copolymer with flexible spacer in the rod block (C) side group liquid crystal-coil (SGLC- coil) diblock copolymers (D) coil -rod-coil ABC triblock copolymers (predicted to be novel ferroelectric fluid by R. G. Petschek and K. M. Wiefling, Phys. Rev. Lett., 1987, 59(3), 343-346) (E) rod-rod diblock copolymer (one example of well-defined po-ly(n-hexyl isocyanate-fc-n-butyl isocyanate) rod-rod diblock copolymer was given by Novak et al. [68], however, no morphology studies were reported) (F) dendritic liquid crystal-coil (DLC-coil) diblock copolymer (not reported).

Another example of sdectivdy addressing the multicom-partmentalized cylinders was introduced by Wang et They have reported that crystalline-coil PFS block copolymers undergo a living supramolecular polymerization to form... 

While the descriptions mentioned so far only apply for block copolymers with coiled blocks, work has also been done on block copolymers with liquid crystalline or crystalline blocks. If one of the two blocks is liquid crystalline, spherical and cylindrical morphologies are predicted to become more stable with the liquid crystalline block forming the core domains at larger values of [110]. 

Fig. 2. Selected architectures of block copolymers (a) diblock (b) triblock (c) comb copolymer consisting of flexible chains (d) rod-coil diblock copolymer consisting of a rodlike block and a coil-like block (e) hairyrods, i.e., comb-block copolymers consisting of rodlike backbone and coil-like side chains and (f) LC coil with a side-chain liquid crystalline (LC) block and a flexible block. Many other variations have been introduced, such as multiblock copolymers, block copolymers consisting of several rodlike blocks, or star-shaped block copolymers. Comb-coil block copolymers with dense packing of side chains are also denoted as molecular bottle brushes, as is illustrated in (g) by a simulated structure of an isolated molecule dissolved in a solvent. (Courtesy of Mika Saariaho.)...

Figure 16.5 TEM images for the micelles self-assembled from (a) Pl32o- -PFS53 in THF/Hexane (2/8, v/v) and (b) Pl3o- -PFS6o in THF/Hexane (3/7 v/v). (Reprinted with permission from L. Cao, I. Manners and M.A. Winnik, Influence of the interplay of crystallization and chain stretching on micellar morphologies Solution self-assembly of coil—crystalline poly(isoprene-block-ferrocenylsilane), Macromolecules, 32, 8258, 2002. 2002 American Chemical Society.)...

Cao, L., Manners, 1., and Winnik, M.A. (2002) Influence of the interplay of crystallization and chain stretching on micellar morphologies solution self-assembly of coil-crystalline poly(isoprene-block-ferrocenylsilane). Macromolecules, 35, 8258. 

If we suppose the conformation of crystalline and amorphous blocks in the lamellar morphology from a thermodynamic viewpoint, random coil conformations are most favorable for amorphous blocks and perfect crystals with no chain folding for crystalline blocks. However, these two... 

Block copolymer micelles in which the core-forming polymer blocks are able to crystallize are relatively similar to rod-coil copolymers. A significant part of these crystalline-core micelles is actually resulting from the self-assembly of rod-coil block copolymers. 

Lee et al. reported the preparation of nanoporous crystalline sheets of penta-p-phenylene using a (oligomeric) block copolymer with a cleavable juncture approach in 2004 [63]. These so-called rod-coil block copolymers of penta-p-phenylene and PPO can self-assemble to give layered phases that contain sheets of perforated crystalline penta-p-phenylene in which the perforations are filled with PPO [64]. The PPO segment is covalently bound to the... 

As we have seen, the phase behaviour of block copolymers consisting of flexible polymer coils is remarkably rich. If one of the blocks is rigid, the copolymer would be expected to exhibit even more complex phase behaviour. For example, the rigid block could be mesogenic. This leads to the possibility of self-assembly of structures consisting of domains of liquid crystalline material within a microphase-separated block copolymer superstructure. Diblock copo-... 

The potential for novel phase behaviour in rod-coil block copolymers is illustrated by the recent work of Thomas and co-workers on poly(hexyl iso-cyanate)(PHIC)-PS rod-coil diblock copolymers (Chen etal. 1996). PHIC, which adopts a helical conformation in the solid state, has a long persistence length (50-60 A) (Bur and Fetters 1976) and can form lyotropic liquid crystal phases in solution (Aharoni 1980). The polymer studied by Thomas and co-workers has a short PS block attached to a long PHIC block. A number of morphologies were reported—wavy lamellar, zigzag and arrowhead structures—where the rod block is tilted with respect to the layers, and there are different alternations of tilt between domains (Chen et al. 1996) (Fig. 2.37). These structures are analogous to tilted smectic thermotropic liquid crystalline phases (Chen et al. 1996). 

These results show that the supramolecular structures of thin films of block copolymers can be manipulated by varying the rod-to-coil ratios. Variables such as the polydispersity, the nature of the structures, and their crystallinity can be controlled in this manner. The factors that govern the formation of ordered structures from these copolymers are, however, complex. Important factors include entropy effects associated with the flexible coil segments, crystallization of the rods, and steric considerations. Upon crystallization of the rods, the entropies of the coil blocks may be increasingly compromised as a result of increasing steric repulsion. This may effect the sizes of the aggregates that are formed. The organization of ordered structures can furthermore be controlled by non-specific interactions such... 

Raez J, Manners I et al (2002) Nanotubes from the self-assembly of asymmetric crystalline — coil poly(ferrocenylsilane — siloxane) block copolymers. J Am Chem Soc 124 10381-10395... 

---