Synthesis and characterization of ladder-like structured polysilsesquioxane with carbazole group

Poly(propyl carbazole silsesquioxane) (PPCSQ) with a high molecular weight (M _w = 10,200) was synthesized by the direct hydrolysis of 9-[3-(trimethoxysilyl) propyl]-9H-carbazole with K₂CO₃, followed by a condensation reaction in an H₂O/dimethylformamide (DMF) mixture solvent at 25 °C. The obtained PPCSQ consisted of ladder-like structured siloxane bonds with carbarzole groups as the pendant group, where the distance between two carbarzole pendant groups through the siloxane backbone was 15.6 Å and the mean thickness of the siloxane backbone was 4.3 Å. This PPCSQ was thermally stable up to 450 °C and the glass transition temperature was ca. 95 °C, showing good film formablity by spin casting.