Synthesis and Thermal Characterization of Novel Fluorene-Based Polysiloxane Derivatives

Three novel poly(tetramethylsilfluorenylenesiloxane) derivatives having different substituent at 9-position of fluorenylene moiety, i.e. dimethyl (P1), spirocyclohexyl (P2), and spirofluorenyl (P3) substituents, were obtained by polycondensation of novel three disilanol monomers, i.e. 2,7-bis(dimethylhydroxysilyl)-9,9-dimethyl- fluorene (M1), 2’,7’-bis(dimethylhydroxysilyl)-spiro(cyclohexane-1,9’-fluorene) (M2), 2,7-bis(dimethylhydroxysilyl)-9,9’-spirobifluorene (M3), respectively. P1–P3 exhibited the good solubility in common organic solvents, such as tetrahydrofuran (THF), chloroform, dichloromethane, and toluene. It was suggested from the differential scanning calorimetry (DSC) and the X-ray diffraction analysis that P1 exhibited the crystallinity whereas P2 and P3 were amorphous polymers. The glass transition temperature (T g) determined by DSC and the temperature at 5% weight loss (T d5) determined by thermogravimetry (TG) were dependent on the substituent at 9-position on fluorene; both orders of T g and T d5 were P3 > P2 > P1, indicating the bulkiness of substituent at 9-position of fluorene resulted in the good thermal stability. It is noteworthy that amorphous P3 exhibiting very high T g of 156 °C and T d5 of 535 °C is a new heat-resistant polysiloxane derivative as well as a promising candidate for blue-light-emitting materials.