Hyperbranched Poly(p-phenylene ethynylene)s

✍ Scribed by James D. Mendez; Michael Schroeter; Christoph Weder

• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 253 KB
• Volume: 208
• Category: Article
• ISSN: 1022-1352
• DOI: 10.1002/macp.200700133

✦ Synopsis

Abstract

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.

magnified image