Poly 2-methoxy-5- 1.4- phenylene

The photodegradation of synthetic polymers can be prohibited (or at least reduced) upon addition of UV-stabilizers. These compounds transform the absorbed light energy into thermal energy thus preventing all sorts of photochemically initiated reactions. Films of poly-(m-phenylene-isophthalamide) were used which contained appropriate amounts of UV-stabilizers of the 2-(2 -hydroxy-5 -methylphenyl)benzotriazole type or their 21-methoxy derivatives. The following results were obtained ... 

FIGURE 5.4 Chemical structures of photo- and electroluminescent polymers employed for polarized LEDs poly(2-methoxy-5-(2 -ethyl-hexyloxy)-p-phenylene vinylene) (MEH-PPV) poly[2,5-dioctyloxy-l, 4-diethynyl-phenylene-a/t-2,5,-bis(2 -ethylhexyloxy)-l,4-phenylene] (EHO-OPPE) poly(p-phenylene), PPP poly(3-(4-octylphenyl)-2,2 -bithiophene), PTOPT poly(p-phenylene vinylene), PPV poly(3-alkylthio-phene vinylene), P3AT Acetoxy-PPY PPV-polyester, poly(9,9-dialkyl fluorene), PF. 

H NMR study of I2 doped poly[2-buthoxy-5-methoxy phenylene vinylene] (PBMPV) has been carried out by Lee et al.114 They found magnetization recovery to follow a stretched-exponential form M(f) =Mo[l — exp(f/Ti) ] with n = 0.8 0.03, which is characteristic of a system with distribution of the correlation time. 1/Tj versus/ 172 in samples with different conductivity follows/ 172 dependence over 20 40 MPIz range indicating the main SLR is ID spin diffusion. A correlation between 1/T1 and dc conductivity has been made which is found follow a simple power law. 

The number of organic materials is of great interest in microelectronic and optoelectronic devices [1], In particular, the conjugated polymers, such as ladder-type methyl substituted poly-para-phenylene (Me-LPPP) and poly[2-methoxy-5-(2-ethylhexyloxy)-l,4-phenylene vinilene] (MEH-PPV) and their nanocomposites, have been widely investigated due to their perspectives in light-emitting diodes and solar cells [2—4]. 

FIGURE 1.2. Molecular structure of widely used it-conjugated and other polymers (a) poly(para-phenylene vinylene) (PPV) (b) a (solid line along backbone) and it ( clouds above and below the a line) electron probability densities in PPV (c) poly(2-methoxy-5-(2 -ethyl)-hexoxy-l,4-phenylene vinylene) (MEH-PPV) (d) polyaniline (PANI) (d.l) leucoemeraldine base (LEB), (d.2) emeraldine base (EB), (d.3) pernigraniline base (PNB) (e) poly(3,4-ethylene dioxy-2,4-thiophene)-polystyrene sulfonate (PEDOT-PSS) (f) poly(IV-vinyl carbazole) (PVK) (g) poly(methyl methacrylate) (PMMA) (h) methyl-bridged ladder-type poly(jf-phenylene) (m-LPPP) (i) poly(3-alkyl thiophenes) (P3ATs) (j) polyfluorenes (PFOs) (k) diphenyl-substituted frares -polyacetylenes (f-(CH)x) or poly (diphenyl acetylene) (PDPA). 

A selection of monosubstituted and disub-stituted poly-(/ -phenylene-terephthalate)s is compared in Table 2. Poly(p-phenylene-terephthalate)s with methyl, methoxy, chlo-ro, or bromo substituents on either the hy-droquinone or the terephthalic acid moiety exhibit melting temperatures of 350 °C or higher. Thermotropic liquid crystalline behavior is observed in these samples, although it is in the range of thermal decomposition. A comparison of the mono- and diphenyl substituted polyesters reveals an important trend. The monosubstituted poly-(p-phenylene-terephthalate) with the phenyl substituent in the hydroquinone moiety melts at 346 °C, also forming a nematic melt up to a clearing temperature of... 

The XPR has been used to synthesize poIy(2,5 dimethoxy p-phenylene vinylene)(DM-PPV) and the reaction is the same as shown in Figure 2 except that methoxy substituents are present at the 2 and 5 positions of the phenylene ring. The chlorine precursor route (CPR) is used to prepare poly(phenoxy phenylene vinylene) (PO-PPV) and the reaction is shown in Figures. ... 

As for CNTs used in polymer composites, their role is to enhance the injection of both electrons and holes into the polymer because of the absence of potential barrier between CNTs and the electrodes [72]. A maximum electroluminescence (EL) efficiency is obtained in poly(methoxy(ethylhexyloxy)-p-phenylene vinylene) (MEHPPV)/SWCNTs with 0.02 wt% CNT concentration, and higher CNT content leads to a decrease in the EL response [73]. 

Other CPs worth mentioning as having been studied for secondary battery applications include poly(3-butyl-thiophene-co-3-methyl-thiophene) and poly(di-methoxy-phenylene vinylene) [730]. Pandey and Prakash [731] investigated a Zn/poly(indole) secondary battery and found a maximum capacity of 90 Ah/kg with an open circuit potential of 1.45 V and good coulombic efficiency. 

Donor polymers D1 = poly 1,4-(2,5-dioctyloxy)-phenyleneethynylene-2,5-thiophenylene-vinylene-1,4-[(5-(2-ethylhexyl) oxy)-2-methyloxyl-phenylene-vinylene and D2 = poly 1,4-(5-[(2-ethylhexyl)-oxy]-2-methoxy)-phenylene-ethynylene-2,5-thiophenylene-vinylene-1,4-l(5-(2-ethylhexyl)oxy)-2-methyloxy]-phenylene-vinylene. ... 

TT-Conjugated linear polymers have attracted attention as materials in organic EL devices. The device using poly(p-phenylene vinylene) (PPV) sandwiched between indium oxide and aluminum electrodes emits green-yellow light at 14 V [167]. The quantum efficiency for the device was up to 0.05% photon per electron. EL devices based on poly[2-methoxy-5-(2 -ethyl)-... 

The sulfonium precursor route may also be applied to alkoxy-substituted PPVs, but a dehydrohalogenation-condensation polymerization route, pioneered by Gilch, is favored 37]. The polymerization again proceeds via a quinomethide intermediate, but die syndicsis of the conjugated polymer requires only two steps and proceeds often in improved yields. The synthesis of the much-studied poly 2-methoxy-5-(2-ethylhexyloxy)-l,4-phenylene vinylene], MEH-PPV 15 is outlined in Scheme 1-5 33, 35]. The solubility of MEH-PPV is believed to be enhanced by the branched nature of its side-chain. 

Poly(2-methoxy, 5-(2 -ethylhexyloxy)-1,4-phenylene vinylene) MEH-PPV Emission peak = 605 nm p-type doping by sulfuric acid (H2SO4) -type doping by sodium (electron donor) Iodine (I2) = electron acceptor = > oxidizing agent... 

Poly(epichlorohydrin) (PECH) and poly(2,6 - dimethyl-1,4-phenylene oxide) (PPO) containing pendant mesogenic units separated form the main chain through spacers of zero to ten methylene units were synthesized and characterized in order to test the "spacer concept." Both polymers were modified by phase transfer catalyzed esterifications of the chloromethyl groups (PECH) or the bromobenzyl groups (brominated PPO) with potassium co -(4-oxybiphenyl) alkanoates and potassium u-(4-methoxy-4-oxybiphenyl)-alk.an oates. While PPO required ten methylene units as a spacer and 4,4 -methoxybiphenyl as mesogen to present thermotropic liquid crystalline mesomorphism,... 

L Smilowitz, A Hays, AJ Heeger, G Wang, and JE Bowers, Time-resolved photoluminescence from poly[2-methoxy, 5-(2-ethyl-hexyloxy)-p-phenylene-vinylene] solutions, gels, films, and blends, J. Chem. Phys., 98 6504-6509, 1993. 

Preparation of Poly[2-(3,7-dimethyloctyloxy)- 5-methoxy-p-phenylene vinylene] (14) (Chart 2.147). 

L. Lutsen, P. Adriaensens, H. Becker, A.J. Van Breemen, D. Vanderzande, and J. Gelan, New synthesis of a soluble high molecular weight poly(arylene vinylene) poly[2-methoxy-5-(3,7-dimethyloctyloxy)-p-phenylene vinylene]. Polymerization and device properties, Macromolecules, 32 6517-6525, 1999. 

F. Wudl and G. Srdanov, Conducting Polymer Formed of Poly(2-Methoxy-5- (2 -Ethylhexyloxy)-p-Phenylene Vinylene), U.S. Patent 5,189,136, February 23, 1993. 

P.L. Burn, A.W. Grice, A. Tajbakhsh, D.D.C. Bradley, and A.C. Thomas, Insoluble poly [2-(2 -ethylhexyloxy)-5-methoxy-l,4-phenylene vinylene] for use in multiplayer light-emitting diodes, Adv. Mater., 9 1171-1176, 1997. 

B. Sohn, K. Kim, D.S. Choi, Y.K. Kim, S.C. Jeoung, and J. Jin, Synthesis and luminescence properties of poly[2-(9,9-dihexylfluorene-2-yl)-l,4-phenylene vinylene] and its copolymers containing 2-(2-ethylhexyloxy)- 5-methoxy-l,4-phenylene vinylene units, Macromolecules, 35 2876-2881, 2002. 

Y.H. Niu, Q. Hou, and Y. Cao, High efficiency polymer light-emitting diodes with stable saturated red emission based on blends of dioctylfluorene-benzothiadiazole-dithienylbenzothiadiazole terpolymers and poly[2-methoxy,5-(2-ethylhexoxy)-l,4-phenylene vinylene], Appl. Phys. Lett., 82 2163-2165, 2003. 

MEH-PPV Poly[2-(2 ethylhexyloxy)-5-methoxy-1,4-phenylene vinylene Red-orange 610... 

Poly[2-methoxy-5-(3, 7 -dimethyloctyloxy)]-l,4-phenylene vinylene Polycyclic aromatic hydrocarbon Poly(3,4-ethylenedioxythiophene)... 

---