Self-Organization of Hairy Rods

Unsubstituted rigid rod polymers typically have a high melting temperature (e.g., ca. 600° C for the polyester of Fig. 25a with a side-chain length n = 0). However, even a short alkyl tail of length 0 n 6 reduces substantially the melting temperature i.e., a 

We now turn our attention to hairy rods consisting of a conjugated polymer backbone, in which case the hairy-rod concept offers possibilities to achieve processible, i.e., soluble or fusible, electroactive materials. It allows one to control the chain conformation in solution [154] and to obtain improved charge transport in the self-organized bulk phase [155]. Here the discussion will still be limited to covalently bonded side chains. In the next section, the extension to supramolecular hairy rods will be considered. 

Alkyl-substituted polythiophenes (see Fig. 26a) have increased solubihty in common solvents [156-158] and show thermo- and sol-vatochromism see the reviews by Inganas [159] and Gustafsson et al. [160]. The self-organized structures in bulk have been systematically studied by Prosa et al. [161] and Chen and Ni [162], demonstrating the formation of self-organized lamellar phases for 

As a further example, unsubstituted poly(p-phenylene) (PPP), which is an insoluble and infusible conjugated polymer will be considered. Based on this polymer, Wegner and co-workers prepared several different types of hairy rods (see Fig. 26c-f) [66, 175,176]. Poly(2,5-di-n-dodecyl-l,4-phenylene) contains two flexible alkyl tails at each aromatic ring (see Fig. 26c) [175]. Such 

Hairy-rod architectures involving polyaniline (PANI) with covalently bonded side chains will be considered briefly. Supramolec-ular hairy-rod architectures of polyaniline will be discussed in considerable detail in the next section. The emeraldine-base (EB) form of polyaniline consists of alternating amine and imine repeat units (see Fig. 32). Side chains have been introduced by covalent connection of short alkyl (methyl or ethyl) chains to the aromatic rings [177] or by a series of different long alkyl chains ranging from butyl to octadecyl to the aminic nitrogens [178] (Fig. 26g). 

---

One of the guiding principles underlying much of the physics in conventional polymers is that many macroscopic macromolecular properties, not least the structure formation, can be satisfactorily understood even when the details of single molecules are ignored [11]. As is discussed later in this review, this idea still remains relevant for the intermolecular self-organization of hairy-rod PFs and for their macroscopic alignment. However, much of the behavior seen in PFs (and virtually all other electronic polymers as well) is an excep-... 

Stepanyan, R., A. Subbotin, M. Knaapila, O. Ikkala, and G. ten Brinke. 2003. Self-organization of Hairy-rod polymers. Macromolecules 3760. 

---