New aromatic diyne monomers of 1,4-diethynyl-2,5-(dihexyloxy)benzene (1), 1,6-diethynyl-2-(hexyloxy)naphthalene (2), and 9,9-bis(4-ethynylphenyl)fluorene (3) are synthesized. Their homopolymerizations and copolymerizations with 1-octyne (4) or phenylacetylene (5) are effected by TaBr5-Ph4Sn and CpCo(CO)(2)-hv, giving soluble hyperbranched polyarylenes with high molecular weights (M-w up to similar to 2.9 x 10(5)) in high yields (up to 99%). The structures and properties of the polymers are characterized and evaluated by IR, NMR, UV, PL, and TGA analysis. The polymers show excellent thermal stability (T-d > 400 degrees C and carbonize when pyrolyzed at 900 degrees C. Upon photoexcitation, the polymers emit deep blue light in the vicinity of similar to 400 nm with fluorescence quantum yields up to 92%. (c) 2007 Wiley Periodicals, Inc.