(617f) In situ Grazing Incidence Small Angle X-Ray Scattering (GISAXS) Study of the Formation of Multilayered Ordered Mesoporous Titania Films
Here, in situ GISAXS is performed to determine if and how orthogonally oriented columnar templated layers form for multilayer Pluronic F127-templated TiO2 films. GISAXS is performed on each layer of multilayer films up to 8 layers (having a total thickness of 1000 nm). Results show that films cast onto modified glass slides maintain vertically oriented mesophase order as multiple layers are deposited. On the other hand, horizontally oriented micelles on unmodified slides lose their preferred orientation as more layers are deposited, and by the third layer a powder pattern is obtained indicating a random mix or orientations in the film. The mesostructure growth kinetics of every layer are analyzed using the Avrami equation to determine the growth rate, order and direction. In situ GISAXS is carried out with varying RH (35% and 70% RH) for F127-templated TiO2films cast onto modified glass. While about 70% relative humidity provides well-ordered, oriented micelles, uniform but randomly oriented micelles are found at 35% RH. These studies, together with complementary SEM imaging, confirm that high relative humidity is important to the formation of orthogonally oriented mesoporous structures, and that thick films with orthogonally oriented pores can be formed by epitaxial growth of o-HCP mesostructures on top of existing o-HCP composite films.
Koganti, V.R., Dunphy, D., Gowrishankar, V., McGehee, M.D., Li, X., Wang, J., Rankin, S.E. 2006. Generalized Coating Route to Silica and Titania Films with Orthogonally Tilted Cylindrical Nanopore Arrays. Nano Letters, 6(11), 2567-2570.
Nagpure, S., Das, S., Garlapalli, R.K., Strzalka, J., Rankin, S.E. 2015. In Situ GISAXS Investigation of Low-Temperature Aging in Oriented Surfactant-Mesostructured Titania Thin Films. The Journal of Physical Chemistry C, 119(40), 22970-22984.