Synthesis and properties of polysiloxanes possessing 9,9-diarylfluorene structure in the main chain

Abstract

Polysiloxanes possessing 9,9-diarylfluorene moieties (F-PSiOs3) were synthesized in 83-91% yield by the polycondensation of 9,9-bis(hydroxyaryl or hydroxyethoxyphenyl)fluorenes with Ph2SiCl2 in the presence of pyridine. F-PSiOs with higher molecular weight (Mn 19000-32000, Mw 32000-75000) were obtained, when less polar solvents such as toluene and CCl4 were used as the polymerization solvent. The F-PSiOs showed good solubility toward various organic solvents, high 5% weight loss temperature (Td5- 443-544°C), and lower glass transition temperature (Tg: 100-171°C) under nitrogen atmosphere rather than 9,9-diarylfluorene-based polymers reported. On the other hand, no melting point (Tm) was observed . owing to the amorphous nature of F-PSiOs. Dynamic viscoelasticity of F-PSiO film was also measured to evaluate the thermal behavior. The transmittance of F-PSiOs in the film state (thickness: 62-70 μm) reached over 90% in the visible region. The F-PSiOs exhibited remarkably high refractive index values in a range of 1.64-1.66 at 589 nm in addition to sufficiently low birefringence values, probably due to the cardo structure of the fluorene moiety placed in the main chain. ©2009 The Society of Polymer Science.