Effect of Inorganic Phase Dimension on Structure and Mechanical Properties of Inorganic-Organic Hybrids Prepared from Metal Alkoxides and Polydimethylsiloxane

Molecular-level and particle-dispersed inorganic-organic hybrids, containing TiO2 as the inorganic component, have been prepared in order to study the effect of the introduced inorganic phase dimension on the structure and properties of the hybrids. The hybrids prepared from silanol-terminated polydimethylsiloxane (PDMS) and titanium ethoxide (Ti(OEt)4) in the molar ratios of Ti(OEt)4/PDMS=1, 2 and 4 were transparent with no visible particles, thus considered as molecular-level hybrids. Inorganic particles of about 50nm in diameter prepared from titanium isopropoxide were dispersed into the molecular level hybrids in the molar ratio of Ti(OEt)4/PDMS=1 to synthesize particle-dispersed hybrids. As a result of differential scanning calorimetry (DSC), increasing the Ti(OEt)4/PDMS ratio in the molecular-level hybrids were found to fix the free PDMS chains more effectively into a three-dimensional network than dispersing particles. The molecular-level hybrids showed a higher Young's modulus and a smaller elongation at break due to the better developed network structure. In the particle-dispersed hybrids, the tensile strength was twice the one without particles. The mechanical properties of the hybrids were found to be affected by the incorporated inorganic phase dimension reflecting the structure of the hybrids.