Influence of the Surface Chemistry of Metal-Organic Polyhedra in Their Assembly into Ultrathin Films for Gas Separation.

The formation of ultrathin films of Rh-based porous metal-organic polyhedra (Rh-MOPs) by the Langmuir-Blodgett method has been explored. Homogeneous and dense monolayer films were formed at the air-water interface either using two different coordinatively alkyl-functionalized Rh-MOPs (HRhMOP(diz) and HRhMOP(oiz)) or by incorporation of aliphatic chains to the axial sites of dirhodium paddlewheels of another Rh-MOP (OHRhMOP) at the air-liquid interface. All these Rh-MOP monolayers were successively deposited onto different substrates in order to obtain multilayer films with controllable thicknesses.

Green Preparation of Thin Films of Polybenzimidazole on Flat and Hollow Fiber Supports: Application to Hydrogen Separation.

This work shows the preparation of thin films, with thickness from 70 nm to 1 μm, of meta-polybenzimidazole (m-PBI) on polyimide P84 supports. Ethanolic solutions of m-PBI were used to coat flat and hollow fiber supports of asymmetric P84 with m-PBI in a process where the coating and drying was performed at room temperature. A solution of NaOH in EtOH allowed the dissolution of the m-PBI powder, providing the perfect coating solution to build thin films of m-PBI without damaging the polymeric support.

Ultrathin Films of Porous Metal-Organic Polyhedra for Gas Separation.

Ultrathin films of a robust Rh -based porous metal-organic polyhedra (MOP) have been obtained. Homogeneous and compact monolayer films (ca. 2.

Poly(ether--amide) copolymer membrane for CO/N separation: the influence of the casting solution concentration on its morphology, thermal properties and gas separation performance.

The present work is focused on the study of the effect that the casting solution concentration has on the morphology and gas separation performance of poly(ether--amide) copolymer membranes (Pebax MH 1657). With this aim, three different concentrations of Pebax MH 1657 in the casting solution (1, 3 and 5 wt%) were used to prepare dense membranes with a thickness of 40 µm. The morphology and thermal stability of all membranes were characterized by scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, rotational viscometry and thermogravimetric analyses.

Nanosheets of MIL-53(Al) applied in membranes with improved CO/N and CO/CH selectivities.

MIL-68(Al) and MIL-53(Al) are carboxylate-based metal-organic frameworks (MOFs) with the same chemical composition but different structures (polymorphs). In this study, MIL-53(Al) nanosheets of ca. 150 nm in size with an average thickness of 3.

The fabrication of ultrathin films and their gas separation performance from polymers of intrinsic microporosity with two-dimensional (2D) and three-dimensional (3D) chain conformations.

The expansion of the use of polymeric membranes in gas separation requires the development of membranes based on new polymers with improved properties and their assessment under real operating conditions. In particular, the fabrication of ultrathin films of high performance polymers that can be used as the selective layer in composite membranes will allow large reductions in the amount of the expensive polymer used and, hence, the cost of membrane fabrication. In this contribution, two polymers of intrinsic microporosity (PIMs) with very different chain configurations (two-dimensional, 2D, chains or conventional contorted three-dimensional, 3D, conformation) have been compared in their ability to form ultrathin films, showing the relevance of polymer design to obtain compact and defect-free films.

Synthesis of ZIF-93/11 Hybrid Nanoparticles via Post-Synthetic Modification of ZIF-93 and Their Use for H /CO Separation.

The present work shows the synthesis of nano-sized hybrid zeolitic imidazolate frameworks (ZIFs) with the rho topology based on a mixture of the linkers benzimidazole (bIm) and 4-methyl-5-imidazolecarboxaldehyde (4-m-5-ica). The hybrid ZIF was obtained by post-synthetic modification of ZIF-93 in a bIm solution. The use of different solvents, MeOH and N,N-dimethylacetamide (DMAc), and reaction times led to differences in the quantity of bIm incorporated to the framework, from 7.

Ultrathin Composite Polymeric Membranes for CO /N Separation with Minimum Thickness and High CO Permeance.

The use of ultrathin films as selective layers in composite membranes offers significant advantages in gas separation for increasing productivity while reducing the membrane size and energy costs. In this contribution, composite membranes have been obtained by the successive deposition of approximately 1 nm thick monolayers of a polymer of intrinsic microporosity (PIM) on top of dense membranes of the ultra-permeable poly[1-(trimethylsilyl)-1-propyne] (PTMSP). The ultrathin PIM films (30 nm in thickness) demonstrate CO permeance up to seven times higher than dense PIM membranes using only 0.