Use of DMF as Solvent Allows for the Facile Synthesis of Soluble MEH−PPV

Abstract

A new method is described for the synthesis of soluble poly(1-methoxy-4-(2-ethylhexyloxy)-p-phenylenevinylene) (MEH−PPV) using N,N-dimethylformamide (DMF) as the solvent. Based on a modification of the traditional Gilch method, the polymerization of α,α‘-dibromo-2-methoxy-5-(2-ethylhexyloxy)xylene was conducted in DMF under a variety of experimental conditions. The resultant MEH−PPVs were characterized and compared to those prepared using analogous syntheses in tetrahydrofuran (THF). Characterization techniques included 1H NMR spectroscopy, UV−vis spectroscopy, and gel permeation chromatography (GPC). Although the molecular weights of the polymers prepared in DMF were routinely lower than those prepared in THF, the polydispersities were as low as (and in most cases lower than) those obtained using THF. Significantly, the use of DMF in polymerizations conducted at 100 °C led to no gelation of the polymer, which circumvented the need for any controlled addition of monomer during the reaction. Moreover, control over the polymer molecular weights in DMF could be achieved using chosen aliquots of the molecular weight modifier 4-(tert-butyl)benzyl bromide and/or by controlling the concentration of the reactants.

Synthesis and characterization of poly(2,5‐didecyl‐1,4‐phenylene vinylene), poly(2,5‐didecyloxy‐1,4‐phenylene vinylene), and their alternating copolymer

“…The alternating copolymer had improved solubility so larger polymer chains could be detected. All samples had comparable polydispersities to those produced by the Gilch method in DMF . Additional information regarding the molecular weight data can be found in the Supporting Information.…”

Origin of the methylene bonds in poly[2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐1,4‐phenylenevinylene] prepared according to Gilch's method: novel applications

“…With the merits of low turn‐on voltage, good solubility and high electroluminescent (EL) efficiency, poly[2‐methoxy‐5‐(2′‐ethyl‐hexyloxy)‐1,4‐phenylenevinylene] (MEH‐PPV) has attracted much attention for its potential applications in polymer light‐emitting diodes (PLEDs) 1–7. The preparation of MEH‐PPV is generally carried out through dehydrohalogenation of 1,4‐bis(halo‐methyl)‐2‐((2′‐ethyl‐hexyl)oxy)‐5‐methoxy‐benzene) monomer, a method that was originally proposed by Gilch and Wheelwright 8.…”

Molecular weight tuning and spectral studies of novel CN‐PPVs via Gilch reaction route

“…However, the nature of the propagating species, radical, or anionic, is not firmly established. 16,17 In the present work, using Gilch reaction alone to synthesize Pa, the resulting polymer was insoluble in common solvent. However, using 4-methoxyphenol as the molecular modifying agent, the molecular weight dropped with the increase of the load of 4-methoxyphenol, and the solubility was dramatically improved.…”

“…The molecular weight could be tuned by changing polymerization conditions. 16,17 Thirdly, the introduction of bulky aromatic ring and cyano groups to conjugated polymers usually helps to enhance the stability, especially the thermal stability. [18][19][20] Herein, two novel series of cyano-containing PPV derivates (CN-PPVs) were designed and successfully synthesized through Gilch 18 reaction from the monomers of 2-cyano-5-(4 0 -alkoxylbenzene)-1,4-bisbromomethyl-benzenes.…”