Rod-coil block

Schlaad H, Smarsly B, Losik M (2004) The role of chain-length distribution in the formation of solid-state structures of polypeptide-based rod-coil block copolymers. Macromolecules 37 2210-2214... 

Scheme 3. Synthetic routes leading to various rod-coil block copolymers via grafting onto" (16a, 16b, 20) or grafting from" (18) reactions.

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... 

Microporous structures form on cast film from rod-coil block copolymer micelles... 

Fig. 9 Schematic representation of three approaches to generate nanoporous and meso-porous materials with block copolymers, a Block copolymer micelle templating for mesoporous inorganic materials. Block copolymer micelles form a hexagonal array. Silicate species then occupy the spaces between the cylinders. The final removal of micelle template leaves hollow cylinders, b Block copolymer matrix for nanoporous materials. Block copolymers form hexagonal cylinder phase in bulk or thin film state. Subsequent crosslinking fixes the matrix hollow channels are generated by removing the minor phase, c Rod-coil block copolymer for microporous materials. Solution-cast micellar films consisted of multilayers of hexagonally ordered arrays of spherical holes. (Adapted from [33])...

The nanoreplication of functional nanostructures has also been achieved through other block copolymer-templated structures. De Boer et al. [35] applied honeycomb-structured films of rod-coil block copolymer as patterned templates to replicate hexagonally packed arrays of aluminum cups on the substrate surfaces (Fig. 10b). Nguyen et al. [237] embedded semiconducting polymers in the channels of oriented hexagonal nanoporous silica and used this nanoscale architecture to control the energy transfer for potential optoelectronic applications. 

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). 

Fig. 2.37 Morphologies of PHIC-PS rod-coil block copolymers studied by Chen et al. (1996). 7bp TEM images from diblocks with different compositions.The dark regions correspond to PS, which have been preferentially stained with RuG4. (A) /,., K- = 0.42 (B) /PHIC = 0.73 (C) /pH,c = 0.89 (D) /Pmc = 0.96 (E) /PHIC = 0.98. The PHIC chain axis and lamellar normals are denoted by n and p. (F, G, H) schematic models showing the packing arrangement of the rod-coil chains. The PHIC block is represented by the white rod, and the PS block by the black ellipsoid. (F) Wavy lamellar morphology (G) zig-zag morphology (H) bilayer and interdigitated arrowhead morphologies.

There have been fewer theories devoted to ordering in rod-coil block copolymers than to coil-coil systems, reflecting the limited amount of experimental work to date on the former. However, recent developments highlight the predictive power of self-consistent field theory for the phase behaviour of these materials, as well as for the simpler phase behaviour of flexible block copolymers. 

Vriezema, D. M., Hoogboom, J., Velonia, K., et al, Vesicles and polymerized vesicles from thiophene-containing rod-coil block copolymers. Angew. Chem., Int. Ed. 2003, 42, 772-776. 

Park, J.-W. Thomas, E. L. Multiple ordering transitions Hierarchical self-assembly of rod-coil block copolymers. Adv. Mater. (Weinheim, Ger.) 15, 585—588 (2003). 

Block copolymers consist of two or more chemically distinct units. A particular well-studied range of materials are rod-coil block copolymers, which consist of a... 

CH20[CH2CH20]mH 80 luminescent rod-coil block copolymer... 

In order to develop active materials for optics, supramolecular structures derived from rod-coil block copolymers appeared to be materials of par-... 

Fig. 15.18. Structures of a few representative rod—coil block copolymers that have been investigated.

Supramolecular Structures from Rod-Coil Block Copolymers... 

Rod—coil block copolymers have both rigid rod and block copolymer characteristics. The formation of liquid crystalline nematic phase is characteristic of rigid rod, and the formation of various nanosized structures is a block copolymer characteristic. A theory for the nematic ordering of rigid rods in a solution has been initiated by Onsager and Flory,28-29 and the fundamentals of liquid crystals have been reviewed in books.30 31 The theoretical study of coil-coil block copolymer was initiated by Meier,32 and the various geometries of microdomains and micro phase transitions are now fully understood. A phase diagram for a structurally symmetric coil—coil block copolymer has been theoretically predicted as a... 

---