Functionalized Poly(tetramethyl-1,4-silphenylenesiloxane) with Pendant Hydroxyl Groups

Novel functionalized poly(tetramethyl-1,4-silphenylenesiloxane) with pendant hydroxyl groups, i.e., poly[2,5-bis(2-hydroxyethoxy)-tetramethyl-1,4-silphenylenesiloxane] (P1), was synthesized and characterized by differential scanning calorimetry (DSC), thermogravimetry (TG), and X-ray diffraction analysis. P1 was obtained via catalytic deprotective-hydrogenation of poly[2,5-bis(2-benzyloxyethoxy)-tetramethyl-1,4-silphenylenesiloxane] (PreP1), which had been obtained by catalytic polycondensation of 2,5-bis(2-benzyloxyethoxy)-1,4-bis(dimethylhydroxysilyl)benzene (M1) in benzene. P1 was revealed to be an amorphous polymer as deduced from DSC as well as X-ray diffraction measurement, and soluble in highly polar solvents as ethanol and methanol in which poly(tetramethyl-1,4-silphenylenesiloxane) (1,4-PTMPS) is insoluble. The glass transition temperature (T g ) of P1 was determined to be 73 °C from DSC, which was much higher than that of 1,4-PTMPS (-20°C), indicating that the intermolecular and/or intramolecular hydrogen bondings based on hydroxyl groups restricted the mobility of the main chain. The temperature at 5% weight loss (T d5 ) of P1 (290°C) determined by TG was lower than that of 1,4-PTMPS, indicating that the oxyethylene and/or alcoholic-hydroxyl moieties decline the thermostability; however, the obtained P1 would promise to be a new reactive-polymer with hydroxyl moieties to develop new functional materials.