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Hyperbranched Poly( p ‐phenylene ethynylene)s
Author(s) -
Mendez James D.,
Schroeter Michael,
Weder Christoph
Publication year - 2007
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.200700133
Subject(s) - polymer chemistry , solid state , coupling reaction , benzene , polymer , poly(p phenylene) , phenylene , chemistry , materials science , crystallography , catalysis , organic chemistry
Hyperbranched poly( p ‐phenylene ethynylenes) (HB‐PPEs) were synthesized in an A 2 + B 3 one‐pot approach by the Pd/Cu‐catalyzed cross‐coupling reaction of 1,4‐diethynyl‐2,5‐bis‐(octyloxy)benzene and 1,2,4‐tribromobenzene. Reaction conditions were varied with the objective to obtain well‐defined HB‐PPEs of different molecular weights. HB‐PPEs with $\overline M _{\rm w}$ from 11 000 to 237 000 g · mol −1 and PDIs of 1.5–10.7 were prepared. All polymers that comprised unreacted ethynyl groups eventually became insoluble upon drying, presumably as a result of solid‐state cross‐linking. This reaction could be prevented by endcapping the polymers with an excess of 4‐iodotoluene.