This article concerns the hydrosilylation polyaddition of 1,4-bis(dimethylsilyl)benzene (1) with 4,4'-diethynylbiphenyl, 2,7-diethynylfluorene (2b), and 2,6-diethynyl naphthalene with RhI(PPh3)(3) catalyst. Trans-rich polymers with weight-average molecular weights (M-w's) ranging from 19,000 to 25,000 were obtained by polyaddition in o-Cl2C6H4 at 150-180 degreesC, whereas cis-rich polymers with Mw's from 4300 to 34,000 were obtained in toluene at 0 degreesC-r.t. These polymers emitted blue light in 4-81% quantum yields. The cis polymers isomerized into trans polymers upon UV irradiation, whereas the trans polymers did not. The device having a layer of polymer trans-3b obtained from 1 and 2b demonstrated electroluminescence without any dopant. (C) 2004 Wiley Periodicals, Inc.