Synthesis and Properties of Organic-Inorganic Hybrid Materials Based on Glycerol

The great supply of glycerol as a byproduct of the production of biodiesel has motivated interest in its use in new applications. In this study, we report the synthesis and properties of organic-inorganic hybrid materials based on glycerol. Glycerol (Gly) was reacted with 3-isocyanatopropyltriethoxysilane (IPTES) in the presence of dibutyltin dilaurate (DBTDL) as a catalyst, using a molar ratio (r = IPTES/Gly) between 0.75 and 3. The sol-gel polycondensation of the resulting precursors in the presence of a formic acid solution led to transparent solid materials with a biphasic structure consisting of glycerol-rich domains dispersed in the organic-inorganic hybrid matrix. An increase in the r value changed the hybrid materials from hydrophilic to hydrophobic. The contact angle of water droplets varied from 43.6 degrees for r = 0.75 to 95.1 degrees for r = 3. Each of the materials exhibited a broad glass-to-rubber transition, with the maximum of the damping peak located in the 54-70 degrees C range. The relatively intense tan delta peaks of the hybrid materials suggest their possible use in devices requiring vibrational damping. The maximum damping capacity corresponded to the hybrid with r = 1.5, which exhibited a loss area LA (area under the loss modulus peak) of 13.5 GPa.K. High values of the rubbery modulus were observed, varying from 130 MPa for r = 0.75 to 720 MPa for r = 3. Values of the glassy modulus were also high, and the maximum value was observed for the hybrid with r = 1.5. The hybrid materials could also be colored through the incorporation of a very small amount of functionalized gold nanoparticles.