Bringing Porous Organic and Carbon‐Based Materials toward Thin‐Film Applications

Abstract

Porous materials have attracted tremendous scientific and industrial interest due to their broad commercial applicability. However, some applications require that these materials are deposited on surfaces to create thin films. Here, the recent progress of new porous thin-film material classes is described: porous organic molecular materials, porous organic polymers, covalent organic frameworks, and nanoporous carbon. In each case, the state of the art and current barriers in their thin-film fabrication, as well as intrinsic material advantages that are suited for different applications are presented. By highlighting the unique structural characteristics and properties of these materials, it is hoped that increased research development and industrial interest will be fostered, which will lead to new methods of thin-film synthesis and consequently to new applications. Figure 2. 1) Structure, crystal packing and BET surface area of triptycene trisbenzimidazolone (TTBI), 2) structure and BET surface area of OMIM-10-14, 3) structure of Doonan cage C1 and BET surface area of the two different crystalline polymorphs obtained by slow and fast precipitation, 4) structure and BET surface area of a triptycene-based cage, 5) structure of Cooper Cage CC3 (cyclohexyl vertices). A) Schematic low-energy crystal packings for CC1 (hydrogens on vertices; formally nonporous), CC2 (methyl vertices; 1D external pore channels), and CC13 (dimethyl vertices; 2D layered pore structure with formally disconnected voids). As such, small structural changes to the vertex groups lead to three quite different crystal packings and pore topologies for the α polymorphs shown here (orange = disconnected voids; yellow = interconnected pores). Crystallization in the presence of 1,4-dioxane causes pseudoisostructural window-to-window packing for all three cage modules, causing the materials to mimic the 3D diamondoid pore structure of CC3 shown in D. B) N 2 sorption isotherms (77 K) for homochiral CC3 produced by freeze-drying (green diamonds, 6 repetitions), vacuum evaporation (blue triangles), standard reaction (black squares), and slow crystallization (red circles, 6 repetitions). C,D) Molecular simulation of amorphous packing (top) and crystalline structure (bottom) of CC3, with the Connolly surface probed by N 2 molecules (kinetic diameter of 3.64 Å) shown in blue, and average BET surface area extracted from the isotherms shown in (B). 1) Reproduced with permission. [58] Figure 12. A) CDC thin-film synthesis and EDLC test cell preparation. Titanium is extracted from titanium carbide as TiCl 4 , forming a porous carbon film. Two carbide plates with the same CDC coating thickness are placed face to face and separated by a polymer fabric soaked with electrolyte. The SEM image (left) shows a representative image of a CDC/TiC interface with a good film adhesion. Reproduced with permission. [187]

Highly conducting Wurster-type twisted covalent organic frameworks

“…In a typical thin film synthesis, a glass substrate was placed horizontally in the COF reaction vessel, and the COF powder synthesis procedure was carried out. 38 After 24 h, the substrate was recovered from the reaction vessel, and the respective COF was obtained as a transparent yet iridescent film on the bottom side of the substrate. To examine the crystallinity of the films, grazing incidence wide-angle Xray scattering (GIWAXS) images were recorded using an incident angle of 0.22° and a 2D…”

Tailoring Covalent Organic Frameworks To Capture Water Contaminants

“…Recent reviewss ummarize the development of COFs as solid sorbents for sample preparation and as chromatographic stationary phases, [6,138] as well as the advances on COF thin films. [139] Magnetic COF materials are, to date, the most explored composites since the superparamagnetic properties imparted by the NPs allow for convenient material separation and retention by an externalm agnetic field, thus avoiding tedious and time-consuming isolation strategies such as filtration or centrifugation.U ntil now,d ifferentm agnetic COF composites were reportedf or the extraction of iodine, [128] bisphenols, [129] and polycyclic aromatic hydrocarbons (PAHs) [130] from water (Table 1).…”

Crucial Factors for the Application of Functional Nanoporous Carbon-Based Materials in Energy and Environmental Applications

“…Both of them aim to keep the transport pathways through the areas with smaller pores as short as possible, and thus, make sure that more than only the external surface of the NPCM particles is used for the desired process. The first one is to decrease at least one particle dimension of the materials down to the nm-scale, that is, shape the NPCMs as thin films [143,144], nanofibers [145,146], or nanoparticles [43,70]. The second way is to introduce hierarchical porosity [28,48].…”