Syntheses and thermal properties of polyesters bearing a carbosilane repeating unit

New polyesters bearing a carbosilane repeating unit (–C–Si(CH₃)₂–C–), 1a and 1b, and reference polyesters with the corresponding carbon-based units 2a and 2b were synthesized and evaluated to study the effect of the carbosilane segment on their thermal properties. DSC analysis revealed that 1a and 1b exhibited glass transition temperatures (T _g) of −72.6 and 11.6 °C, respectively, which were lower than those of 2a and 2b (–53.2 °C for 2a and 63.6 °C for 2b), indicating that the substitution of carbon atoms on polyester backbone with silicone atoms is effective method to change the T _g of polyesters. Furthermore, 1a and 1b showed good thermal stability (T _d5 = 304 °C for 1a and 309 °C for 2a). These results indicate that carbosilane segment may be a promising soft segment for developing new polyester-based materials.