Phase behavior of ordered mesoporous silica film prepared by Brij-76 block copolymer

Phase behavior of ordered mesoporous silica film was investigated according to the solvent and Brij-76 block copolymer molar ratio. From grazing incidence small angle X-ray scattering and transmission electron microscopy analysis, we found that the lyotropic mesophase diagram exhibited body-centered cubic (bcc), two-dimensional hexagonal and lamellar structures with a mixed phase region. The existence of the mixed phase region indicated fast structuration during spin coating. The ordered mesoporous silica film using Brij-76 block copolymer had a three-dimensional pore structure with distorted bcc arrangement in a wide composition range, while the ordered mesoporous silica using Brij-76 block copolymer displayed a three-dimensional mesophase with a hexagonal close-packed or cubic close-packed arrangement. We suggest that the thick ethylene oxide chains in the corona region govern micelle aggregation behavior, favoring the formation of the less tightly coordinated bcc structure during the fast structuration process.