Evaluation of molecular volume of siloxane bonding and phenyl group in partially phenylated organic/inorganic hybrid glass

The molecular volume of the siloxane bonding and phenyl groups in partially phenylated organic/inorganic hybrid glass were evaluated from the density. The partially phenylated organic/inorganic hybrid glass were prepared by sol–gel method starting from TEOS (tetraethylorthosilicate) and PTES (phenyltriethoxysilane) mixed at various molar ratios. The molar volume of the hybrid glass exhibited a completely linear dependence on the molar fraction of PTES showing that the molecular volumes of the siloxane parts and phenyl groups are constant irrespective of the molar fraction of PTES. From the obtained dependence of the molar volume on the added molar fraction, the molecular volumes of the siloxane bonding and phenyl group were estimated. Finally, the percolation threshold of the volume fraction of phenyl group was estimated from using the obtained molecular volumes.