Hydrophobic Thin Films from Sol–Gel Processing: A Critical Review

Fabrication of hydrophobic thin films from a liquid phase is a hot topic with critical technological issues. Interest in the production of hydrophobic surfaces is growing steadily due to their wide applications in several industrial fields. Thin films from liquid phases can be deposited on different types of surfaces using a wide variety of techniques, while the design of the precursor solution offers the possibility of fine-tuning the properties of the hydrophobic coating layers. A general trend is the design of multifunctional films, which have different properties besides being hydrophobic. In the present review, we have described the synthesis through sol–gel processing of hydrophobic films enlightening the main achievements obtained in the field.

Sol-Gel Processing of a Covalent Organic Framework for the Generation of Hierarchically Porous Monolithic Adsorbents

Covalent organic frameworks (COFs) have emerged as a versatile materials platform for applications including chemical separations, water purification, chemical reaction engineering and energy storage. Their inherently low mechanical stability, however, frequently renders existing methods of pelletisation ineffective contributing to pore collapse, pore blockage or insufficient densification of crystallites. Here, we present a general process for the shaping and densifying of COFs into centimetre-scale porous monolithic pellets without the need for templates, additives or binders. This process minimises mechanical damage from shear-induced plastic deformation and further provides a network of interparticle mesopores that we exploit in accessing analyte capacities above those achievable from the intrinsic porosity of the COF framework. Using a lattice-gas model, we accurately capture the monolithic structure across the mesoporous range and tie pore architecture to performance characteristics in both gas storage and separation applications. Collectively, these findings represent a substantial step in the practical applicability of COFs and other mechanically weak porous materials.

Sol-Gel Processing of a Covalent Organic Framework for the Generation of Hierarchically Porous Monolithic Adsorbents

Covalent organic frameworks (COFs) have emerged as a versatile materials platform for applications including chemical separations, water purification, chemical reaction engineering and energy storage. Their inherently low mechanical stability, however, frequently renders existing methods of pelletisation ineffective contributing to pore collapse, pore blockage or insufficient densification of crystallites. Here, we present a general process for the shaping and densifying of COFs into centimetre-scale porous monolithic pellets without the need for templates, additives or binders. This process minimises mechanical damage from shear-induced plastic deformation and further provides a network of interparticle mesopores that we exploit in accessing analyte capacities above those achievable from the intrinsic porosity of the COF framework. Using a lattice-gas model, we accurately capture the monolithic structure across the mesoporous range and tie pore architecture to performance characteristics in both gas storage and separation applications. Collectively, these findings represent a substantial step in the practical applicability of COFs and other mechanically weak porous materials.