Design, Synthesis, and Properties of Inorganic and Hybrid Thin Films Having Periodically Organized Nanoporosity

Abstract

This review presents an extensive discussion on the major advances in the field of periodically organized mesoporous thin films (POMTFs) obtained via surfactant templated growth of inorganic or hybrid polymers. A large variety of templating agents can be coupled with inorganic polymerization reactions for the design of periodically organized nanostructured hybrid phases that yield POMTFs. The tuning of the interface between the template and the polymerizing phase and the control over chemical and processing conditions are the key parameters in producing tailor-made POMTFs with a high degree of reproducibility. This dynamic coupling between chemical and processing conditions dictates extensive use of complementary ex situ measurements with in situ characterization techniques that follow, in real time, film formation from the molecular precursor solutions to the final stabilized POMTF. Among modern analytical tools, 2D-GISAXS, ellipsoporosimetry, HRTEM, X-ray reflectometry, WAXS, time-resolved infrared spectroscopy, SAW, and optically polarized xenon NMR have proved to be highly relevant for this purpose. POMTFs combine the intrinsic physical and chemical properties of the inorganic or hybrid matrices with a highly defined nanoporous network having a tunable pore size and connectivity, high surface area and accessibility, and a specific orientation with respect to the substrate. As such, POMTFs are a promising family of advanced materials for a host of future applications including micro-optics and photonic devices, microelectronics, nanoionics and energy, environment, functional and protective coatings, biomaterials, environmentally responsive materials, and biomicrofluidics, among others.

Macroporous WO3 Thin Films Active in NH3 Sensing: Role of the Hosted Cr Isolated Centers and Pt Nanoclusters

“…41 No variations in the W4f profile or energy position were recorded depending on the doping with different species or under different annealing atmosphere. In addition, the nature of the O1s peak (BE = 530.5 eV) supports the formation 37 and chemical stability of the WO 3 network for all the samples. Doping of WO 3 layers with platinum led to the formation of zerovalent species of the noble metal, as it was observed from the analysis of Pt-related XPS lines.…”

Large-Pore Mesoporous Ho3Fe5O12 Thin Films with a Strong Room-Temperature Perpendicular Magnetic Anisotropy by Sol–Gel Processing

“…As already indicated by AFM and TEM, the degree of pore ordering is not very high and is certainly less pronounced than in other polymer-templated nonsilicate oxides. [31][32][33][34][35][39][40][41][42][43][44] However, considering that the garnet material studied in this work is much more complex than the many binary oxides reported in the literature over the past two decades, the overall structure seems rather well-developed. The GISAXS patterns further indicate significant lattice contraction in the direction perpendicular to the substrate plane as a result of the progressive densification of the inorganic matrix and the associated release of NO x and H 2 O (see TGA-MS data in Figure S3 in the SI) upon heating; the in-plane contraction is negligible.…”

“…28,29 This process goes back to Brinker and coworkers; the basics of EISA have been described in detail in many papers and are not discussed here. [30][31][32][33][34][35] Similar to our recent work on mesostructured Y 3 Fe 5 O 12 films, 36 the synthesis is based on the coassembly of common hydrated nitrate salts with a polymer structure-directing agent (SDA). However, unlike the yttrium compound, the HoIG thin films show no typical signs of superparamagnetism, and further exhibit a large perpendicular magnetic anisotropy.…”

Low temperature crystallisation of mesoporous TiO2

“…A subsequent high temperature step degrades the organic material and crystallises the TiO 2 to result in an inorganic nanocrystalline network of high morphological order. This approach has attracted significant interest 11 because it allows detailed control over pore size 12 and porosity 13 of the resulting inorganic thin films.…”