Poly Phenylene-Vinylene

Oriented material can be described in terms of a paracrystalline structure. On doping with AsFs, order is retained, with a new spacing developing perpendicular to the chain axis and a regular positioning of dopant along the chains 499 . 

The soluble polythiophenes are the first conducting polymers that can be taken above their glass transition without decomposition and it will be interesting to study morphology-property relationships. Heeger et al.262) have recently described conformational changes in solutions of poly-3-hexylthiophene which seem to involve a coil-helix transformation as the temperature is decreased or a poor solvent is added. 

In general, doping tends to lead to a loss of x-ray order in polyacetylene and polyphenylene, suggesting that dopant ions may be distributed more or less at random. The structural models shown in Fig. 16 are clearly idealised as only limited order is seen even in cation-doped polymer. The anion dopants are much larger and apparently disrupt the structure too much for any sign of regularity to be seen, except in the case of iodine. 

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Single layer OLEDs have been fabricated with a variety of emitter molecules and conjugated polymers such as poly(phenylene vinylene) (PPV). 

Mattoussi, H. Radzilowski, L. H. Dabbousi, B. O. Thomas, E. L. Bawendi, M. G. Rubner, M. F. 1998. Electroluminescence from heterostructures of poly(phenylene vinylene) and inorganic CdSe nanocrystals. J. Appl. Phys. 83 7965-7974. 

U Lemmer, D Vacar, D Moses, and AJ Heeger, Electroluminesence from poly(phenylene vinylene) in a planar metal-polymer-metal structure, Appl. Phys. Lett., 68 3007-3009, 1996. 

Controlling the Conjugation in Poly(/>Phenylene Vinylene) Polymers... 

S. Iwatsuki, M. Kubo, and T. Kumeuchi, New method for preparation of poly(phenylene vinylene) film, Chem. Lett., 2 1971-1974, 1991. 

I. Murase, T. Ohnishi, T. Noguchi, and M. Hirooka, Highly conducting poly(phenylene vinylene) derivatives via soluble precursor process, Synth. Met., 17 639-644, 1987. 

C.L. Gettinger, A.J. Heeger, J.H. Drake, and D.J. Pine, A photoluminescence study of poly (phenylene vinylene) derivatives the effect of intrinsic persistence length, J. Chem. Phys., 101 1673-1678, 1994. 

L.M. Leung and G.L. Chik, Phase-transfer catalysed synthesis of disubstituted poly(phenylene vinylene), Polymer, 34 5174—5179, 1993. 

L.-S. Yu and S.A. Chen, Full-range tunability of electron and hole carrier mobilities and density ratios via incorporation of highly electron-deficient moieties in poly(phenylene vinylene) side chains, Adv. Mater., 16 744-748, 2004. 

R. Zhang, G. Zhang, and J. Shen, A new approach for the synthesis of conjugated-non-conjugated poly(phenylene vinylene) — polyacrylamide copolymers, Chem. Commun823-824, 2000. 

M.-Y. Hwang, M.-Y. Hua, and S.-A. Chen, Poly(pyridine-2,5-diyl) as electron-transport/hole blocking layer in poly(phenylene vinylene) light-emitting diode, Polymer, 40 3233-3235, 1999. 

M.J. Marsella, D.-K. Fu, and T.M. Swager, Synthesis of regioregular poly(methyl pyridinium vinylene) an isoelectric analogue to poly(phenylene vinylene), Adv. Mater., 7 145-147, 1995. 

DDC Bradley, RH Friend, FI Lindenberger, and S Roth, Infra-red characterization of oriented poly(phenylene vinylene), Polymer, 27 1709-1713, 1986. 

C. Fou, O. Onitsuka, M. Ferreira, M.F. Rubner, and B.R. Hsieh, Fabrication and properties of light-emitting diodes based on self-assembled multilayers of poly(phenylene vinylene), J. Appl. Phys., 79 7501-7509, 1996. 

Other common emissive conjugated polymers with aromatic ring backbones are poly(phenylene vinylenes) (PPVs), poly(fluorenes) (PFs) - usually formed as copolymers such as poly(fluorene-co-phenylene)s (PFPs), and, more rarely, poly (p-phenylene)s (PPPs). Hetero-aromatic based polymers and copolymers alternating... 

Wu T-Y, Chen Y (2004) Poly(phenylene vinylene)-based copolymers containing 3,7-phenothiazylene and 2, 6-pyridylene chromophores fluorescence sensors for acids, metal ions, and oxidation. J Polym Sci A Polym Chem 42 1272-1284... 

Montano GA, Dattelbaum AM, Wang H-L, Shreve AP (2004) Enhanced photoluminescence from poly(phenylene vinylene) dendrimer polyelectrolyte assemblies in solution. Chem Commun 2490-2491... 

Fig. 4.13 (a) Semilogarithmic plot of conductivity versus the nanotube content (wt%) in poly(phenylene vinylene-co-2,5-dioctoxy-m-phenylene vinylene) (PMPV) [2]. (b) Frequency dependent conductivity of carbon nanotubes at different wt% in PmPV (filled symbols) and polyvinyl alcohol (PVA) (unfilled symbols) based composites [250]. 

Fig. 1 Building units of conducting polymers, (1) polyacetylene (PA) (2) polypyrrole (PPy), polythiophene (PTh), polyfurane (PFu) (3) polyphenylene (PP) (4) polyaniline (PANI) 5 polyindole (PIND) (6) polycarbazole (PCaz) (7) polyazulene (Paz) (8) polynaphthalene (PNa) (9) polyanthracene (PAnth) (10) polypyrene (PPyr) (11) polyfluorene (PFiu) (12) poly(isothionaphthalene) (PITN) (13) poly(dithienothiophene) (14) poly(thienopyrrole) (15) poly(dithienylbenzene) (1G) poly(3-alkylthiophene) (17) poly(phenylene vinylene) (18) poly(bipyrrole) (PBPy), poly(bithiophene) (PBT) (19) poly(phenylenesulfide) (20) 4-poly(thienothiophene) (21) poly(thienyl vinylene), poly(furane vinylene) (22) poly(ethylenedioxythiophene) (PEDOT).

Poly(phenylene-ethynylene) Poly(phenylene-vinylene [PPE] [PPV]... 

Poly( -phenylene vinylene) (PPV) was the first reported (1990) polymer to exhibit electroluminescence. PPV is employed as a semiconductor layer. As noted earlier, the layer was sandwiched between a hole-injecting electrode and electron-injecting metal on the other. PPV has an energy gap of about 2.5 eV and thus produces a yellow-green luminescence. Today, other materials are available, which give a variety of colors. 

The basic poly(phenylene vinylene) (PPV) polymer is commonly prepared by the sufonium prepolymer route developed by WessUng and Zimmerman in 1968 but much modified by subsequent workers. The synthesis starts from 1,4-bis(chloromethyl)benzene, via the bis-sulfonium salt formed by reaction with tetrahydrothiophene, and then polymerisation is effected to give the prepolymer by reaction with lithium hydroxide (Figure 3.39). Because of the inherent insolubility of PPV it is this prepolymer that is used to form the film coating on the substrate, for example by using a doctor blade technique. The prepolymer is converted into PPV on the substrate by heating in an oven under vacuum at 200 °C for 8-10 h. 

Tanase C, Wildeman J, Blom PWM, Mena Benito ME, de Leeuw DM, van Breemen AJJM, Herwig PT, Chlon CHT, Sweelssen J, Schoo HEM (2005) Optimization of the charge transport in poly(phenylene vinylene) derivatives by processing and chemical modification. J Appl Phys 97 123703... 

The cross-coupling polymerization with dihaloarenes leads to poly(phenylene-vinylene)s (PPVs), which are widely employed as conductive and electroluminescent polymers. ... 

Synthesis of several bridged macrocylic poly( -phenylene-vinylene)s 44 is also reported by Naso. The presence of such a ring structure improves the emission properties of the synthesized polymer more than that of non-bridged and branched polymer 45 (Equations (21) and (22)). 

Sengupta showed that the reaction of bis-arenediazonium salt 91 with vinyl(triethoxy)silane 92 afforded poly(phenylene-vinylene) 93. Although the reaction apparently proceeds through the Heck reaction mechanism, which is described in Section 11.19.4, a part of the step-growth reaction is indeed a transformation of the carbon-silicon bond of 92 to the carbon-carbon bond (Equation (44)). 

Gibson and coworkers utilized the expected complexation between crown ethers and acrylonitrile for the preparation of poly(acrylonitrile-crown ether rotax-ane)s 94 [137]. Relative to that with the polystyrene backbone, the enhanced threading supported the intermediacy of the expected complex. The reaction intermediates, the cations 95 and 96 in the preparation of poly(phenylene vinylene) (PPV) also provided a source for interaction with crown ethers [70], The solution polymerization of precursor 95 in the presence of crown ethers followed by transformation of 96 produced polyrotaxanes 97. 

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