Ralf-Peter Winkler

The Sol-gel process for nano-technologies : new nanocomposites with interesting optical and mechanical properties

Various nanocomposite systems have been synthesized by sol-gel routes. For this reason, prefabricated nanoparticles (SiO2 sols or boehmite powder) have been dispersed after surface modification in sol-gel-derived organically modified or polymeric ligand matrices. In all cases, a significant effect on dispersibility by surface modification could be observed. After curing, the mechanical or optical properties depend strongly on the dispersion and surface modification. Using these results, composites to be used in chip coupling and as hard coatings on polycarbonate and CR 39 have been developed.

New UV-curable adhesives with variable refractive index based on inorganic-organic nanocomposites (NANOMER) for optical components

New transparent UV-curable adhesives for the use in integrated optics based on organic-inorganic nanocomposites (NANOMER) have been developed. These adhesives show excellent optical properties, whereby a high content of SiO2 particles with an average particle size of 10 nm can be achieved (up to 35 vol-%). The thermal expansion coefficient could be reduced from 75 ppm/K down to 30 ppm/K with a filler content of 20 wt-% (15 vol-%). The refractive index could be varied from 1.450 (cured 1.461) to 1.546 (cured 1.558), at a wavelength of 644 nm, by variation of the synthesis. UV-curing was faster compared to UV-curable commercial epoxy resins.