Fluorene, anionic polymerization

Rod—coil molecules containing structurally perfect conjugated rods were synthesized by using a-(phen-yl)-ft -(hydroxymethyl phenyl)-poly(fluoren-2,7-ylene) as macroinitiator (Scheme 8).98 Anionic polymerization of ethylene oxide by using the macroinitiator produced a corresponding rod—coil block copolymer (22). The absorption and emission measurements of... 

An optically active polymer has been obtained from 2,7-di-n-pentyldibenzofulvene (PDBF) by anionic polymerization using chiral anionic initiators. The optical activity of the polymer arises only from a chiral conformation. In this polymer, the fluorene moieties are in a t-stacked assembly which may be twisted in a single sense. 

Although the exact mechanism of the fluorenone formation is not known, it is believed that the monoalkylated fluorene moieties, present as impurities in poly(dialkylfluorenes), are the sites most sensitive to oxidation. The deprotonation of rather acidic C(9)—H protons by residue on Ni(0) catalyst, routinely used in polymerization or by metal (e.g., calcium) cathode in LED devices form a very reactive anion, which can easily react with oxygen to form peroxides (Scheme 2.26) [293], The latter are unstable species and can decompose to give the fluorenone moiety. It should also be noted that the interaction of low work-function metals with films of conjugated polymers in PLED is a more complex phenomenon and the mechanisms of the quenching of PF luminescence by a calcium cathode was studied by Stoessel et al. [300],... 

The electropolymerization of fluorene (Fig. 26) produces a polymer with a conductivity of 10 S cm. By functionalizing carbon 9 of the five-membered ring, substituted fluorenes have also been oxidized to form polymers of 9-methylfluorene, 9,9 -dimethylfluorene, and 9-phenylfluorene. These polymers gave comparable voltammograms, which seems to indicate that the substituents are not directly involved in the polymerizations. The doped polymers contained tetrafluoroborate anions, but their conductivities were very low [382,383]. The samples were analyzed by elemental analysis, infrared spectroscopy, electron spin resonance, and scanning electron microscopy. 

Figures shows the potential range where some heterocycles polymerizeThe cathodic cutoff for the polymerization (around 1.2 V) occurs when the stability of the radical cation is enhanced (intrinsically or via a substituent). When becomes greater than kp - - k ([S] + PC ]) diffusion of R+ from the electrode results in the production of soluble products. The anodic cutoff (around 2.1 V) occurs when k,([S] -t- [X ]) > (kp -t- k ). Then R" becomes unstable and reacts with the solvent or anions. Between around 1.2 and 2.1 V good conditions for the electropolymerization of such monomers exists where kp > k q- k ([S] -f- [X ]). The influence of substituents in pyrroles, thiophenes, indoles, azulenes, fluorenes, and pyrenes on whether electropolymerization of the monomers or other reactions can occur has been discussed in detail including consideration of electronic or steric effects...

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