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Efficient Oxygen‐Induced Molar‐Mass Control of Poly( p ‐phenylene vinylenes) Synthesized via the Gilch Route
Author(s) -
Schwalm Thorsten,
Rehahn Matthias
Publication year - 2008
Publication title -
macromolecular rapid communications
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.348
H-Index - 154
eISSN - 1521-3927
pISSN - 1022-1336
DOI - 10.1002/marc.200700609
Subject(s) - molar mass , phenylene , polymer chemistry , poly(p phenylene) , molar ratio , oxygen , molar , materials science , chemical engineering , chemistry , polymer , organic chemistry , composite material , catalysis , medicine , dentistry , engineering
Oxygen is shown to act as an efficient molar‐mass regulating agent in Gilch syntheses of PPV. As a scavenger, it undergoes instantaneous recombination with the initiating diradicals as soon as they appear in the system. Regular polymer formation can only start when all oxygen has been used, proceeding predominantly as chain‐growth polymerization of the p ‐quinodimethane monomers. Since all radical species involved in this Gilch process are diradicals, some polyrecombination events occur in parallel. Therefore the initially formed peroxy diradicals are also incorporated into the resulting chains. Later, they break under very mild conditions, thereby causing a systematic decrease of the final molar mass of PPV.