Raman microprobe study of transparent poly(ethylene oxide)/silica hybrids

A transparent organic/inorganic hybrid, which is simple to prepare by the sol-gel process, is poly(ethylene oxide) (PEO)/silica. The reason for its simplicity is that PEO is soluble in water and mixes easily with bonds with silanols. Hybrids of PEO/silica were prepared with PEO molecular weights 200, 1000, 2000, 3400, and 8000. Raman microscopy was used look at environmental effects of the polymer in the silica spectra. Both the hydrogen-bonding between the organic and inorganic components and the steric effects of the organic component resulted in changes in the Raman spectra. With low molecular weight PEO, the spectra showed large shifts in CH bands. For high molecular weight PEO, the spectra showed broadening, indicative of more fluid behavior of the PEO. The interaction between the ether oxygens and the silica network varied with molecular weight and the ratio of PEO to silica.