New hyperbranched polyarylenes of high molecular weights are synthesized in high yields by copolycyclotrimerizations of diynes 1,4-diethynylbenzene, 4,4'-diethynylbiphenyl, 2,7-diethynylfluorene and 2,5-diethynylthiophene with monoynes 1-heptyne, 1-octyne and 1-dodecyne catalyzed by TaCl5-Ph4Sn in toluene. All the polymers show good solubility in common organic solvents, possess excellent thermal stability, and emit strong deep-blue lights of similar to 400 nm with quantum efficiencies up to 98%. The polyarylenes effectively limit 532 nm lasers light, some of which show optical limiting performances superior to that of C-60, a well-known optical limiter. (c) 2005 Elsevier Ltd. All rights reserved.