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Toward Controlled Gilch Synthesis of Poly(p-phenylenevinylenes): Synthesis and Thermally Induced Polymerization of α-Bromo-p-quinodimethanes

Schwalm, Thorsten and Rehahn, Matthias (2007):
Toward Controlled Gilch Synthesis of Poly(p-phenylenevinylenes): Synthesis and Thermally Induced Polymerization of α-Bromo-p-quinodimethanes.
In: Macromolecules, pp. 3921-3928, 40, (11), ISSN 0024-9297, [Online-Edition: http://dx.doi.org/10.1021/ma062649f],
[Article]

Abstract

It is general consensus that in Gilch polymerizations the 1,4-bis(halomethylene)benzene starting material first changes into an α-halo-p-quinodimethane intermediate which then acts as the real active monomer in the subsequent chain growth process. Recently, we could verify the formation of α-chloro-p-quinodimethane directly via in-situ NMR spectroscopy at low temperatures. However, quantitative formation of this p-quinodimethane was not possible there. Now, we show that even such quantitative conversion into the active monomer is possible if bromomethylene-functionalized starting materials are used instead of their chloromethylene counterparts. Moreover, it is even possible to induce chain growth leading to PPV in a very controlled way by carefully warming the obtained solution of p-quinodimethane. In this manner, the temperature can be determined where chain growth startsand hence thermal energy is sufficient for the initiating process. Finally, we could reconfirm that the chain growth is a radical polymerization here as well, initiated by diradicals formed via spontaneous dimerization of a low number of α-bromo-p-quinodimethane monomers. This proof could be provided by quantitatively analyzing the effect of 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO): depending on the molar ratio of monomer and scavenger, the chain growth is either retarded or completely prevented.

Item Type: Article
Erschienen: 2007
Creators: Schwalm, Thorsten and Rehahn, Matthias
Title: Toward Controlled Gilch Synthesis of Poly(p-phenylenevinylenes): Synthesis and Thermally Induced Polymerization of α-Bromo-p-quinodimethanes
Language: English
Abstract:

It is general consensus that in Gilch polymerizations the 1,4-bis(halomethylene)benzene starting material first changes into an α-halo-p-quinodimethane intermediate which then acts as the real active monomer in the subsequent chain growth process. Recently, we could verify the formation of α-chloro-p-quinodimethane directly via in-situ NMR spectroscopy at low temperatures. However, quantitative formation of this p-quinodimethane was not possible there. Now, we show that even such quantitative conversion into the active monomer is possible if bromomethylene-functionalized starting materials are used instead of their chloromethylene counterparts. Moreover, it is even possible to induce chain growth leading to PPV in a very controlled way by carefully warming the obtained solution of p-quinodimethane. In this manner, the temperature can be determined where chain growth startsand hence thermal energy is sufficient for the initiating process. Finally, we could reconfirm that the chain growth is a radical polymerization here as well, initiated by diradicals formed via spontaneous dimerization of a low number of α-bromo-p-quinodimethane monomers. This proof could be provided by quantitatively analyzing the effect of 2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPO): depending on the molar ratio of monomer and scavenger, the chain growth is either retarded or completely prevented.

Journal or Publication Title: Macromolecules
Volume: 40
Number: 11
Divisions: DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue > A - Synthesis > Subproject A5: Synthesis of semiconducting model polymers and their characterization before and after cyclic electrical fatigue
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue > A - Synthesis
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres > CRC 595: Electrical fatigue
Zentrale Einrichtungen
DFG-Collaborative Research Centres (incl. Transregio) > Collaborative Research Centres
DFG-Collaborative Research Centres (incl. Transregio)
Date Deposited: 04 Aug 2011 15:02
Official URL: http://dx.doi.org/10.1021/ma062649f
Additional Information:

SFB 595 A5

Identification Number: doi:10.1021/ma062649f
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