ORGANICALLY MODIFIED SILICATES AND CERAMICS AS 2-PHASIC SYSTEMS - SYNTHESIS AND PROCESSING

Based on the concept of controlling the particle size by the surface f ree energy, the growth of sol-gel derived nanoparticles (Al2O3, TiO2, ZrO2) has been investigated in presence of molecules with binding abil ity to the growing particles. The investigations show that the use of silanes, carboxylic acid or B-diketones allows to replace electrostati c sol stabilisation by steric sol stabilisation and through this, high solid content sols can be obtained. The introduction of these sols in to organic or ormocer type of matrices leads to nano composites with d egrees of filling up to 40 wt.-% without agglomeration and with high o ptical quality. Already developed TiO2 containing bulk materials, ultr ahard coatings on plastic and adhesives for fiber to chip coupling are examples for the usefulness of this alternative sol-gel route. The na nocomposite materials show interesting mechanical and thermomechanical properties such as high hardness or low thermal expansion compared to unfilled systems.