One of the simpler organic/inorganic hybrids to prepare by the sol-gel process is polyethylene (PEO)/silica. The reason for its simplicity is that PEO is soluble in water. PEO contains ether oxygens -(O-CH2-CH2-)- that readily form hydrogen bonds. The refractive index of PEO is low, 1.4537, and its glass transition temperature can be as low as minus 65 degrees Celsius, generally making it a crystalline polymer at room temperature. Hybrids of PEO/silica were prepared with molecular weights 200, 1000, 2000, and 3400. The lower molecular weights (200 and 1000) produced transparent hybrids over a range of loadings. The higher molecular weights (greater than 2000) produced samples that were sensitive to the loading and especially the time of mixing before the samples were cast into closed containers. These trends indicate a competition between the reactions that lead to gelling and the tendency to phase separate. By following these trends, both the scale of the microstructure and the degree of transparency was adjusted.