Deformation of Mesoporous Titania Nanostructures in Contact with D₂O Vapor

Abstract

For many applications, mesoporous titania nanostructures are exposed to water or need to be backfilled via infiltration with an aqueous solution, which can cause deformations of the nanostructure by capillary forces. In this work, the degree of deformation caused by water infiltration in two types of mesoporous, nanostructured titania films exposed to water vapor is compared. The different types of nanostructured titania films are prepared via a polymer template assisted sol-gel synthesis in conjunction with a polymer-template removal at high-temperatures under ambient conditions versus nitrogen atmosphere. Information about surface and inner morphology is extracted by scanning electron microscopy and grazing incidence small-angle neutron scattering (GISANS) measurements, respectively. Furthermore, complementary information on thin film composition and porosity are probed via X-ray reflectivity. The backfilling induced deformation of near surface structures and structures inside the mesoporous titania films is determined by GISANS before and after D O infiltration. The respective atmosphere used for template removal influences the details of the titania nanostructure and strongly impacts the degree of water induced deformation. Drying of the films shows reversibility of the deformation.

Anisotropic and Reversible Deformation of Mesopores and Mesostructures in Silica-Based Films under Mechanical Stimuli toward Adaptive Optical Components

“…Similar changes of the mesostructure with compression were observed on the mesoporous silica film (Figure S3). It has been reported that silica-based mesoporous materials have flexibility because their mesostructures change through swelling by water adsorption. − The results presented here are the first observation to demonstrate that the anisotropic and reversible changes of the mesostructures of surfactant/silica hybrid and mesoporous silica films can be controlled by mechanical compression.…”

Micro-Nano Machining TiO2 Patterns without Residual Layer by Unconventional Imprinting

“…Firstly, PMMA loaded with titanium salt (PMMA/Ti 4+ ) in the xylene solution was spincoated on the surface of PDMS template. In the spin-coating process, the solution is filled into the template by capillary force, forming the meniscus between air and liquid within the concave field [19,[21][22][23]. Secondly, the hydroxyl was modified on the surface of the PMMA/Ti 4+ film and the substrate by the O 2 Plasma.…”

Tailoring Ordered Mesoporous Titania Films via Introducing Germanium Nanocrystals for Enhanced Electron Transfer Photoanodes for Photovoltaic Applications

“…Moreover, this finding also agrees well with the observation reported recently. [42] To illustrate the influence of GeNC addition on the titania morphology, an illustration of the evolution of the titania-DBC films with incorporated GeNCs is presented in Figure 4. With a so-called good-bad solvent pair, the PS-b-PEO diblock copolymer undergoes a micro-phase separation and self-assembles into spherical micelles.…”

“…[37][38][39][40] A detailed description of this GISAXS modeling can be found elsewhere. [41] Cylinder form factors have been successfully used to model the nanostructures in mesoporous films in the literature, [25,41,42] and thus are applied in the present data analysis. The horizontal line cuts and modeling results for the air-annealed films are shown in Figure 3a.…”