Transport Behavior of Tailored Carbon Nanomembranes

Dalpke R. Transport Behavior of Tailored Carbon Nanomembranes. Bielefeld: Universität Bielefeld; 2020

Electron-induced chemistry of surface-grown coordination polymers with different linker anions

Ahlenhoff K, Koch S, Emmrich D, Dalpke R, Gölzhäuser A, Swiderek P. Electron-induced chemistry of surface-grown coordination polymers with different linker anions. Physical Chemistry Chemical Physics. 2019;21(5):2351-2364.Electron beam processing of surface-grown coordination polymers is a versatile approach to the fabrication of nanoscale surface structures. Depending on their molecular components, these materials can be converted into pure metallic particles or they can be activated to become a template for the spatially selective decomposition of suitable gaseous precursor molecules and subsequent autocatalytic growth of deposits. However, insight into the fundamental electron-induced chemistry for such processes has been scarce so far. Therefore, we investigated the electron-induced reactions of three self-assembled copper-containing materials, namely, copper(ii) oxalate, copper(ii) squarate, and copper(ii) 1,3,5-benzenetricarboxylate (HKUST-1) which were grown on the surface of self-assembled monolayers of mercaptoundecanoic acid in a layer-by-layer approach from copper(ii) acetate and various linker molecules. Changes incurred to these materials during electron irradiation were monitored by four complementary techniques. Reflection absorption infrared spectroscopy (RAIRS) and X-ray photoelectron spectroscopy (XPS) were used to identify the chemical species that are formed upon electron exposure. The temporal evolution of electron-stimulated desorption (ESD) of neutral volatile fragments was monitored to reveal the kinetics governing the decomposition of the different materials. Furthermore, the morphology was investigated by helium ion microscopy (HIM). A detailed analysis of the results for the different linker molecules provides new insights into the electron-induced chemistry of such surface-grown layers

Fusion of purple membranes triggered by immobilization on carbon nanomembranes

Riedel R, Frese N, Yang F, et al. Fusion of purple membranes triggered by immobilization on carbon nanomembranes. Beilstein journal of nanotechnology. 2021;12:93–101.A freestanding ultrathin hybrid membrane was synthesized comprising two functional layers, that is, first, a carbon nanomembrane (CNM) produced by electron irradiation-induced cross-linking of a self-assembled monolayer (SAM) of 4'-nitro-1,1'-biphenyl-4-thiol (NBPT) and second, purple membrane (PM) containing genetically modified bacteriorhodopsin (BR) carrying a C-terminal His-tag. The NBPT-CNM was further modified to carry nitrilotriacetic acid (NTA) terminal groups for the interaction with the His-tagged PMs forming a quasi-monolayer of His-tagged PM on top of the CNM-NTA. The formation of the Ni-NTA/His-tag complex leads to the unidirectional orientation of PM on the CNM substrate. Electrophoretic sedimentation was employed to optimize the surface coverage and to close gaps between the PM patches. This procedure for the immobilization of oriented dense PM facilitates the spontaneous fusion of individual PM patches, forming larger membrane areas. This is, to our knowledge, the very first procedure described to induce the oriented fusion of PM on a solid support. The resulting hybrid membrane has a potential application as a light-driven two-dimensional proton-pumping membrane, for instance, for light-driven seawater desalination as envisioned soon after the discovery of PM. Copyright © 2021, Riedel et al

Examination of Interpenetrating Polymer Networks of Polyurea in Silicone Molds Arising during Vacuum Casting Processes

Wortmann M, Frese N, Heide A, et al. Examination of Interpenetrating Polymer Networks of Polyurea in Silicone Molds Arising during Vacuum Casting Processes. POLYMER-PLASTICS TECHNOLOGY AND ENGINEERING. 2018;57(15):1524-1529

Combined nanofiltration and advanced oxidation processes with bifunctional carbon nanomembranes

Shapira B, Penki TR, Cohen I, et al. Combined nanofiltration and advanced oxidation processes with bifunctional carbon nanomembranes. RSC Advances. 2021;11(24):14777-14786.Wastewater reclamation is becoming a top global interest as population growth and rapid industrialization pose a major challenge that requires development of sustainable cost-effective technologies and strategies for wastewater treatment. Carbon nanomembranes (CNMs)-synthetic 2D carbon sheets-can be tailored chemically with specific surface functions and/or physically with nanopores of well-defined size as a strategy for multifunctional membrane design. Here, we explore a bifunctional design for combined secondary wastewater effluent treatment with dual action of membrane separation and advanced oxidation processes (AOP), exploiting dissolved oxygen. The bifunctional membrane consists of a CNM layer on top of a commercial ultrafiltration membrane (Microlon (TM)) and a spray-coated reduced graphene oxide (rGO) thin film as the bottom layer. The CNM/support/rGO membrane was characterized by helium ion and atomic force microscopy, FTIR, XPS with a four-point conductivity probe, cyclic voltammetry, galvanostatic measurements, and impedance spectroscopy. Combined treatment of water by nanofiltration and AOP was demonstrated, employing a unique three electrode-dead end filtration setup that enables concurrent application of potential and pressure on the integrated membrane. For the model organic compound methylene blue, oxidation (by the Fenton reaction) was evaluated using UV-vis (610 nm). The rejection rate and permeability provided by the CNM layer were evaluated by dissolving polyethylene glycol (400 and 1000 Da) in the feed solution and applying pressure up to 1.5 bar. This demonstration of combined membrane separation and AOP using an integrated membrane opens up a new strategy for wastewater treatment

Protein Nanopore Membranes Prepared by a Simple Langmuir-Schaefer Approach

Schwieters MS, Mathieu-Gaedke M, Westphal M, et al. Protein Nanopore Membranes Prepared by a Simple Langmuir-Schaefer Approach. Small. 2021;17(46): 2102975.Filtration through membranes with nanopores is typically associated with high transmembrane pressures and high energy consumption. This problem can be addressed by reducing the respective membrane thickness. Here, a simple procedure is described to prepare ultrathin membranes based on protein nanopores, which exhibit excellent water permeance, two orders of magnitude superior to comparable, industrially applied membranes. Furthermore, incorporation of either closed or open protein nanopores allows tailoring the membrane's ion permeability. To form such membranes, the transmembrane protein ferric hydroxamate uptake protein component A (FhuA) or its open-pore variant are assembled at the air-water interface of a Langmuir trough, compressed to a dense film, crosslinked by glutaraldehyde, and transferred to various support materials. This approach allows to prepare monolayer or multilayer membranes with a very high density of protein nanopores. Freestanding membranes covering holes up to 5 mum in diameter are visualized by atomic force microscopy (AFM), helium ion microscopy, and transmission electron microscopy. AFM PeakForce quantitative nanomechanical property mapping (PeakForce QNM) demonstrates remarkable mechanical stability and elastic properties of freestanding monolayer membranes with a thickness of only 5nm. The new protein membrane can pave the way to energy-efficient nanofiltration. © 2021 The Authors. Small published by Wiley-VCH GmbH