Hyperbranched polyarylenes

Alkyne polycyclotrimerizations are effected by tantalum- and cobalt-based catalysts, giving soluble hyperbranched polyarylenes (HPAs) with high molecular weights (M-w up to similar to2 X 10(5)) in high yields (up to 99.9%). All the HPAs exhibit excellent thermal stability. losing little of their weights when heated to > 400 degreesC. The HPAs graphitize when pyrolyzed at 800 degreesC in high yields (up to 86%). Upon photoexcitation, the HPAs efficiently emit strong deep-blue and blue-green light with fluorescence quantum yields LIP to 98%. The HPAs strongly attenuate intense laser pulses, with their limiting performances being superior to that of C-60, a well-known optical limiter. (C) 2003 Academie des sciences. Published by Editions scientifiques et medicales Elsevier SAS. All rights reserved.