1,3-Dichloro-1,1,3,3-tetraphenyldisilazane (DCTPS) with 71.6% yield was synthesized by the reaction of hexaphenylcyclotrisilazane (HPCT) with Ph2SiCl2 catalyzed by dibutyltin dilaurate. A ring-closure reaction of DCTPS was carried out with BuLi in xylene-hexane mixture solvent; 1,3-bis (chlorodiphenylsilyl)-2,2,4,4-tetraphenyl-cyclodisilazane (BcPTPC) with 73.2% yield was obtained. Hydrolysis of BcPTPC in ether-triethylamine solvent resulted in 71.9% yield of 1,3-bis(diphenylhydroxysilyl)-2,2,4,4-tetraphenylcyclodisilazane (BHPTPC). By condensation polymerization of BHPTPC with alpha,omega-bis(diethylamino)-oligo-dimethylsiloxane, a kind of alternate copolymer constructed by 1,3-bis(diphenylsilyl)-2,2,4,4-tetraphenylcyclodisilazane units with oligo-dimethylsiloxane segments [P(BPTPC-altODMS)] was synthesized. BcPTPC, BHPTPC as well as P(BPTPC-alt-ODMS) were characterized by Si-29-NMR spectra, FT-IR spectra, and elemental analysis. DGA study shows that P(BPTPC-alt-ODMS)s are thermally stable. The thermal decomposition onsets of P(BPTPC-alt-ODMS)s are all above 520 degrees C. (c) 2005 Wiley Periodicals, Inc.