The growth mechanism of continuous cubic mesoporous SBA-16 film with a large area of highly ordered pores

For SBA-16 films, the pore connectivity as well as the working properties are closely dependent on the growth mechanism. In this paper, the growth mechanism of SBA-16 films prepared by use of a dip-coating method was investigated, and it is clearly revealed that the SBA-16 films grow in a layer-by-layer fashion, different from the well-known growth mechanism of SBA-16 particles. Due to the gradient variation in the block copolymer concentration, the SBA-16 layers first form at the solution/air interface and subsequently gradually develop down to the solution/substrate interface, resulting in the production of continuous SBA-16 films with a large area of highly ordered pores. Although the layer thickness is almost the same at 35-50 nm, it is found that the inner layers in the films have more ordered pores than the outer layers close to both the film surface and the film/substrate interface. Explanations have been suggested for this phenomenon based on microstructural analyses.