Investigations on the mobility of novel sol-gel processed inorganic-organic hybrid materials

Novel co-condensing agents of the type R'Si(OMe)(2)(CH2)(3)R2Si(CH2)(3)Si(O Me)(2)R' {3[Me2Si(C3D0)(2)] (3a), R = Me, R' = Me; 3[Me2Si(C3T0)(2)] (3b), R = Me, R' = OMe; 4[Et2Si(C3D0)(2)] (4a), R = Et, R' = Me; 4[Et2Si(C3T0)(2) ] (4b), R = Et, R' = OMe} were synthesised by hydrosilylation of the corres ponding diallyldialkylsilanes 1, 2 with dichloro(methyl)silane and trichlor osilane, respectively, followed by treatment with trimethyl orthoformate. T hese precursors were sol-gel processed with or without PhSi(OMe)(3) [Ph(T-0 )] to give the xerogels X3a-d, X4a-d. The polysiloxane matrices, the degree of condensation and the integrity of the hydrocarbon backbone were investi gated by means of solid state NMR spectroscopy (C-13, Si-29). To study the polymer dynamics in the dry state Si-29 CP/MAS NMR measurements of relaxati on times (T-1 rhoH) and cross-polarisation parameters (T-SiH) were carried out. H-1 HR/MAS NMR experiments and T-1 rhoH measurements in different solv ents were undertaken to get information on the mobility of the polymers in suspension. Scanning electron microscopy (SEM) images show the morphology o f the polymers and energy dispersive X-ray spectroscopy (EDX) suggests that the distribution of the elements agrees with the applied stoichiometry.