Highly ordered orthorhombic mesoporous silica films

Mesoporous silica films are made by the spin-coating technique using an ethylene oxide-propylene oxide-ethylene oxide triblock copolymer (Pluronic PE6800) as template. After optimization of the polymer concentration in the silica sol, films are textured and organized over all the thickness. They exhibit an orthorhombic symmetry (a = 16.0 nm, b = 10.2 nm, c = 23.0 nm) with the b-axis perpendicular to the substrate. This results from a body-centered cubic (bcc) micellar structure which is deformed along the [0 11]_bcc cubic axis, i.e. perpendicular to the film plane.