Macromolecules hairy rod

By means of a repetitive Suzuki aryl-aryl cross-coupling method, developed by Schliiter, Wegner and co-workers, the synthesis of solubilized PPP s 6 with a dramatically increased molecular weight (number average up to 100 1,4-pheny-lene units) was possible [12]. 2,5-Dialkyl-substituted PPPs 6 were intensively studied as prototypes of so-called hairy-rod macromolecules, composed of a linear, rigid PPP main-chain and flexible, hairy alkyl side-chains. The individual, shape-persistent macromolecules can be imaged by transition electron microscopy within monolayers [16]. Poly(2,5-di-n-dodecyl-l,4-phenylene) 6 (R -C12H25) revealed a sandwich-type structure with layers of aliphatic side-chains perpendicular and layers of the PPP main-chain parallel to the substrate surface. 

Figure 9.2. The design elements of hairy-rod macromolecules (a) and (b) side chains attached to a wormlike backbone (c) backbones embedded in the amorphous matrix of the side-chain segments [71]...

Figure 9.3. Constitutive units of tjfpical hairy-rod macromolecules PcPS = phthalocyaninato-poly(sil-oxane)s PG = copoly(glutamate)s PS = poly(silane)s IPC = isopentylceUulose PPP = poly(p-phen-ylene)s. In the case of PcPS and PG, a pictorial representation of the shape of the HRM is given (see text) [71]...

Figure 9.4. Schematic representation of the different steps in the construction of supramoleculax layered architectures of hairy-rod macromolecules by the LB technique and flow-induced in-plane orientation of the backbone elements to provide for a frozen-in nematic order in terms of a monodomain (ideaUzed depiction) in each monolayer transferred [81]...

The multilayers of hairy-rod macromolecules behave as solids in regard to their mechanical properties, but as liquids in regard to their optical and other properties. In fact, the... 

Wegner G (2003) Nanocomposites of hairy-rod macromolecules concept, constructs, and materials, Macromol Chem Phys 204 347-357. 

Figures 9.2, 9.3, 9.5 and 9.6 are from Macromolecular Chemistry and Physics, Vol. 204, 2003, Author Wegner G, Title Nanocomposites of hairy-rod macromolecules concept, constructs, and materials, pp. 347-357, Copyright (2003), with permission from Wiley-VCH, Weinheim, Germany. 

Dense substitution of side chains along a main chain gives brush-like macromolecules such as hairy rods [15], worm-like brushes [16-21] or, in the case of the side chains, further branching and monodendron jacketed chains [22-26]. 

Knaapila M, Dias FB, Garamus VM, Almasy L, Torkkeli M, Leppanen K, Galbrecht F, Preis E, Burrows HD, Scherf U, Monkman AP (2007) Influence of side chain length on the self-assembly of hairy-rod poly(9,9-dialkylfluorene)s in the poor solvent methyl-cyclohexane. Macromolecules 40 9398-9405... 

Knaapila M, Garamus VM, Dias FB, Almasy L, Galbrecht F, Charas A, Morgado J, Burrows HD, Scherf U, Monkman AP (2006) Influence of solvent quality on the self-organization of archetypical hairy rods - Branched and linear side chain polyfluorenes Rodlike chains versus beta-sheets in solution. Macromolecules 39(19) 6505-6512... 

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

Lieser, G., M. Oda, T. Miteva, A. Meisel, H.G. Nothofer, and U. Scherf 2000. Ordering, graphoe-pitaxial orientation, and conformation of a polyfluorene derivative of the hairy-rod type on an oriented substrate of polyimide. Macromolecules 33 4490. 

Knaapila, M., et al. 2005. The influence of the molecular weight on the thermotropic alignment and self-organized structure formation of branched side chain hairy-rod polyfluorene in thin films. Macromolecules 38 2744. 

The interesting class of macromolecules denoted as hairy rods can be successfully used for overcoming this obstacle. What is more important in this particular case, these macromolecules can be very well used to construct supramolecular architectures by the Langmuir-Blodgett technique. It is also worthwhile to emphasize the very small value of thickness per monolayer of 9.6 A for the isopentylcellulose of degree of substitution 3 [100]. 

Vierheller T R, Forster M D, Schmidt A, Mathauer K, KnoU W, Wegner G, Satija S and Majkrzak C F (1994) Structure and thermal-stability of Langmuir-Blodgett-Kuhn layers of hairy-rod polymers probed with neutron and X-ray reflectometry, Macromolecules 27 6893-6902. 

Knaapila, M., Stepanyan, R., Lyons, B.P., TorkkeU, M., Hase, T.P.A., Serimaa, R., Giintner, R., Seeck, O.H., Scherf, U., Monkman, A.P. The influence of the molecular weight on the thermotropic alignment and self-organized stmcture formation of branched side chain hairy-rod polyfluorene in thin films. Macromolecules 38(7), 2744—2753 (2005)... 

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