9,9-Diarylfluorene-based monomers capable of controlling the thermal properties Of the corresponding polymers Were synthesized. The monomers possess flexible alkylene chains linking 9,9-diarylfluorene units with diphenol, dialcohol. and diamine terminal units. All of these terminal Units were synthesized from it common trimeric tert-alcohol-functionalized intermediate. Polycarbonates consisting of the 9,9-diarylfluorene trimer structure in the main chains were synthesized by interfacial polycondensation with triphosgene. The polymerizability of the diphenolic trimer Wits sufficiently high to afford a polycarbonate with a high molecular weight (M-w 334000). The thermal properties (T-g and T-d) of the polymers were easily controlled by adjusting the feed ratio of the 9,9-diarylfluorene trimer to 9,9-bis-(4-hydroxyphenyl)fluorene. The resulting highly transparent polymers showed high refractive indices and low birefringence Values originating from the cardo structure.