Generation of Self‐Assembled 3D Mesostructured SnO₂ Thin Films with Highly Crystalline Frameworks

Abstract

Crack‐free, mesoporous SnO2 films with highly crystalline pore walls are obtained by evaporation‐induced self‐assembly using a novel amphiphilic block‐copolymer template (“KLE” type, poly(ethylene‐co‐butylene)‐block‐poly(ethylene oxide)), which leads to well‐defined arrays of contracted spherical mesopores by suitable heat‐treatment procedures. Because of the improved templating properties of these polymers, a facile heat‐treatment procedure can be applied whilst keeping the mesoscopic order intact up to 600–650 °C. The formation mechanism and the mesostructural evolution are investigated by various state‐of‐the‐art techniques, particularly by a specially constructed 2D small‐angle X‐ray scattering setup. It is found that the main benefit from the polymers is the formation of an ordered mesostructure under the drastic conditions of using molecular Sn precursors (SnCl4), taking advantage of the large segregation strength of these amphiphiles. Furthermore, it is found that the crystallization mechanism is different from other mesostructured metal oxides such as TiO2. In the case of SnO2, a significant degree of crystallization (induced by heat treatment) already starts at quite low temperatures, 250–300 °C. Therefore, this study provides a better understanding of the general parameters governing the preparation of mesoporous metal oxides films with crystalline pore walls.

Block Copolymer Assemblies as Templates for the Generation of Mesoporous Inorganic Materials and Crystalline Films

“…It might become the basis for the generation of oriented films by simple chemical coating means. The special functionality of crystalline oxide films has been explored both for SnO 2 [39] and WO 3 . [40] In the case of SnO 2 , it was shown that the resulting porous thin-films are conducting, which is a prerequisite for their use as sensors and as electrodes.…”

Periodic Mesoporous Organosilica in Confined Environments

“…The difference in the diffraction patterns from the laboratory instrument and the ones obtained at the synchrotron can be explained by the different measurement geometries. [25] Due to the relatively low photon flux and the larger beam size of the in-house diffractometer, the incident angle of the beam with respect to the sample has to be set to 108 in order to observe diffraction patterns intense enough for evaluation. Using the high photon flux of the synchrotron, it was possible to reduce the www.chemeurj.org incident angle to 2.358, resulting in the diffraction patterns depicted in Figure 2C.…”

Nanoarchitectonics for Mesoporous Materials

“…Smarsly's group prepared mesoporous non-siliceous metal oxide films with various framework compositions by using the novel surfactant, poly(ethylene-co-butylene)-block-poly(ethylene oxide) (KLE). 452 KLE has a high thermal stability caused by strong hydrophobichydrophilic contrast in its chemical structure. Niederberger et al reported a new synthetic route to mesoporous tin oxide structures by self-assembly of nanosized tin oxide crystal nanoparticles and block copolymer.…”