Nanoporous Block Research Articles

Slippery Coatings with Durable Contaminant Resistance Enabled by Specific Interactions between Nanoporous Block Copolymers and Lubricants

Slippery Coatings with Durable Contaminant Resistance Enabled by Specific Interactions between Nanoporous Block Copolymers and Lubricants

CataLight: The Collaborative Research Center for Light-Driven Catalysis in Soft Matter.

This invited Team Profile was created by the Collaborative Research Center for Light-Driven Catalysis in Soft Matter, CataLight, located at Friedrich Schiller University Jena, Ulm University, Max Planck Institute of Polymer Research (MPI) and Johannes Gutenberg University Mainz, University of Vienna, and the Center of Electron Microscopy, Ulm University. The authors, who include members of the Kranz and Leopold Groups, the Schacher Group, and the Streb Group, recently published an article on local measurements of light-driven activity at heterogenized water oxidation catalysts using nanoporous block copolymers: "Multimodal Analysis of Light-Driven Water Oxidation in Nanoporous Block Copolymer Membranes", J. Kund, J.-H. Kruse, A. Gruber, I. Trentin, M. Langer, C. Read, G. Neusser, D. Blaimer, U. Rupp, C. Streb, K. Leopold, F. H. Schacher, C. Kranz, Angew. Chem. Int. Ed. 2023, e202217196.

CataLight: The Collaborative Research Center for Light‐Driven Catalysis in Soft Matter

AbstractThis invited Team Profile was created by the Collaborative Research Center for Light‐Driven Catalysis in Soft Matter, CataLight, located at Friedrich Schiller University Jena, Ulm University, Max Planck Institute of Polymer Research (MPI) and Johannes Gutenberg University Mainz, University of Vienna, and the Center of Electron Microscopy, Ulm University. The authors, who include members of the Kranz and Leopold Groups, the Schacher Group, and the Streb Group, recently published an article on local measurements of light‐driven activity at heterogenized water oxidation catalysts using nanoporous block copolymers: “Multimodal Analysis of Light‐Driven Water Oxidation in Nanoporous Block Copolymer Membranes”, J. Kund, J.‐H. Kruse, A. Gruber, I. Trentin, M. Langer, C. Read, G. Neusser, D. Blaimer, U. Rupp, C. Streb, K. Leopold, F. H. Schacher, C. Kranz, Angew. Chem. Int. Ed. 2023, e202217196.

Multimodal Analysis of Light-Driven Water Oxidation in Nanoporous Block Copolymer Membranes.

Heterogeneous light-driven catalysis is a cornerstone of sustainable energy conversion. Most catalytic studies focus on bulk analyses of the hydrogen and oxygen evolved, which impede the correlation of matrix heterogeneities, molecular features, and bulk reactivity. Here, we report studies of a heterogenized catalyst/photosensitizer system using a polyoxometalate water oxidation catalyst and a model, molecular photosensitizer that were co-immobilized within a nanoporous block copolymer membrane. Via operando scanning electrochemical microscopy (SECM), light-induced oxygen evolution was determined using sodium peroxodisulfate (Na2 S2 O8 ) as sacrificial electron acceptor. Ex situ element analyses provided spatially resolved information on the local concentration and distribution of the molecular components. Infrared attenuated total reflection (IR-ATR) studies of the modified membranes showed no degradation of the water oxidation catalyst under the reported light-driven conditions.

Multimodale Analyse lichtinduzierter Wasseroxidation in nanoporösen Blockcopolymer‐Membranen**

AbstractDie heterogene lichtgetriebene Katalyse ist ein Eckpfeiler nachhaltiger Energieumwandlung. Die meisten katalytischen Studien konzentrieren sich auf die Analyse von Wasserstoff und Sauerstoff, wobei in der Regel über die Gesamtantwort gemittelt wird, und somit eine Korrelation von Heterogenitäten der Matrix mit unterschiedlichen molekularen Aktivitäten limitiert ist. Hier berichten wir von Untersuchungen eines heterogenisierten Katalysator‐Photosensibilisator‐Systems, bei dem ein Polyoxometalat‐Katalysator zur Wasseroxidation und ein molekularer Modell‐Photosensibilisator gemeinsam in einer nanoporösen Blockcopolymer‐Membran immobilisiert wurden. Mittels elektrochemischer Rastersondenmikroskopie (SECM) wurde die lichtinduzierte Sauerstoffentwicklung mit Natriumperoxodisulfat (Na2S2O8) als Opferelektronenakzeptor an den modifizierten Blockcopolymer‐Membranen lokal bestimmt. Ex situ elementspezifische Analysen erzielten räumlich Informationen über die lokale Konzentration und Verteilung der molekularen Komponenten. Untersuchungen der modifizierten Membranen mittels abgeschwächter Infrarot‐Totalreflexion (IR‐ATR) zeigten keinen Abbau des Wasseroxidationskatalysators unter den beschriebenen lichtinduzierten Bedingungen.

Highly Efficient Production of Nanoporous Block Copolymers with Arbitrary Structural Characteristics for Advanced Membranes.

The great significance of boosting the design of percolating nanopore structures in block copolymers (BCPs) for various cases has been widely demonstrated in the past several decades. However, it still remains challenging to prepare the desired porous structures in a rapid, facile, and universal manner. Here we have developed an unconventional and benchtop strategy to rapidly generate the nanoporous polystyrene-based BCPs with arbitrary structural characteristics regardless of the BCP bulk morphology. This universal pore-forming strategy enables the sustainable CO2 -based BCPs to form advanced membranes after 1 s soaking for efficiently rejecting 94.2 % brilliant blue R (826 g mol-1 ). Meanwhile, the water permeance retains around 1020 L (m2 h bar)-1 , which is 1-3 orders of magnitude higher than that of other membranes. This strategy may offer an excellent opportunity to introduce percolating pore structures in those newly developed BCPs with which the previously reported pore-forming methods may not deal.

Highly Efficient Production of Nanoporous Block Copolymers with Arbitrary Structural Characteristics for Advanced Membranes

AbstractThe great significance of boosting the design of percolating nanopore structures in block copolymers (BCPs) for various cases has been widely demonstrated in the past several decades. However, it still remains challenging to prepare the desired porous structures in a rapid, facile, and universal manner. Here we have developed an unconventional and benchtop strategy to rapidly generate the nanoporous polystyrene‐based BCPs with arbitrary structural characteristics regardless of the BCP bulk morphology. This universal pore‐forming strategy enables the sustainable CO2‐based BCPs to form advanced membranes after 1 s soaking for efficiently rejecting 94.2 % brilliant blue R (826 g mol−1). Meanwhile, the water permeance retains around 1020 L (m2 h bar)−1, which is 1–3 orders of magnitude higher than that of other membranes. This strategy may offer an excellent opportunity to introduce percolating pore structures in those newly developed BCPs with which the previously reported pore‐forming methods may not deal.

Application of W/O Drilling Fluid in Horizontal Well with Long Horizontal Sections in Oil Shale Formations

To address the challenges of oil shale formation well wall instability,micro and nano pore blocking, long horizontal section well friction and borehole purification.We have analysed the nature of formation lithology,matrix pore size and specific surface by using linear expansion method,rolling recovery method and nuclear magnetic resonance method,and developed a white W/O drilling fluid system with an oil-to-water ratio of 70:30 by developing emulsifiers,tackifying and shear strength-improving agents,plugging agents and preferably filter loss agents,and wetting agents.The system was evaluated by using the breakthrough pressure test triaxial compression test and relaxation measurement method in the laboratory. The evaluation results showed that the system could not only maintain the strength of the rock sample but also improve the plasticity of the rock sample after the drilling fluid soaked with the breakthrough pressure of 6.5MPa,and it had good suspension capacity after the relaxation value reached 60s.The field test results show that the system has stable rheological properties and solves the problems of well wall instability and borehole purification,with the well diameter expansion rate of only 3.8% and the mechanical drilling speed of up to 10.85m/h.The SY-1 well has set a record for the longest horizontal section of 1800m in the Liaohe River oil area.

Nanoporous Block Copolymer Membranes with Enhanced Solvent Resistance Via UV‐Mediated Cross‐Linking Strategies

Front Cover: A block copolymer containing UV-addressable benzophenone moieties within the hydrophobic block is synthesized via atom transfer radical polymerization (ATRP). The block copolymer is utilized in a self-assembly non-solvent induced phase separation process to obtain an integral asymmetric membrane, which can be stabilized upon UV- irradiation revealing enhanced solvent and pressure resistance. This work is featured in article number 2100632 by Bizan N. Balzer, Markus Gallei, and co-workers.

Multimodal analysis of visible light-driven water oxidation catalysis in nanoporous block copolymer membranes

Multimodal analysis of visible light-driven water oxidation catalysis in nanoporous block copolymer membranes

Nanoporous Block Copolymer Membranes with Enhanced Solvent Resistance Via UV-Mediated Cross-Linking Strategies.

In this work, a block copolymer (BCP) consisting of poly((butyl methacrylate-co-benzophenone methacrylate-co-methyl methacrylate)-block-(2-hydroxyethyl methacrylate)) (P(BMA-co-BPMA-co-MMA)-b-P(HEMA)) is prepared by a two-step atom-transfer radical polymerization (ATRP) procedure. BCP membranes are fabricated applying the self-assembly and nonsolvent induced phase separation (SNIPS) process from a ternary solvent mixture of tetrahydrofuran (THF), 1,4-dioxane, and dimethylformamide (DMF). The presence of a porous top layer of the integral asymmetric membrane featuring pores of about 30nm is confirmed via scanning electron microscopy (SEM). UV-mediated cross-linking protocols for the nanoporous membrane are adjusted to maintain the open and isoporous top layer. The swelling capability of the noncross-linked and cross-linked BCP membranes is investigated in water, water/ethanol mixture (1:1), and pure ethanol using atomic force microscopy, proving a stabilizing effect of the UV cross-linking on the porous structures. Finally, the influence of the herein described cross-linking protocols on water-flux measurements for the obtained membranes is explored. As a result, an increased swelling resistance for all tested solvents is found, leading to an increased water flux compared to the pristine membrane. The herein established UV-mediated cross-linking protocol is expected to pave the way to a new generation of porous and stabilized membranes within the fields of separation technologies.

Selective ion transport through three-dimensionally interconnected nanopores of quaternized block copolymer membranes for energy harvesting application.

A concentration gradient in an aqueous solution is a promising source of energy that can be converted into electrical energy by an ion-exchange polymer membrane. In concentration-gradient energy harvesters, ion transport through nanoporous channels is an emerging approach to enhance the energy conversion efficiency. Since massive but selective ion transport could be realized through nanochannels, the theoretical calculations predicted that nanoporous membranes can extract significantly larger energy than the conventional non-structured membranes. In this regard, scientists in the field have attempted to produce nanoporous membranes on a macroscopic scale based on 1D, 2D, and 3D materials. However, the fabrication of nanoporous membranes is often accompanied by technical difficulties, which entails high production cost, low throughput, and poor scalability. In this study, we took advantage of the self-segregating properties of block copolymers (BCPs) to address these issues. In particular, the non-solvent-induced phase separation method has been utilized to produce three-dimensionally interconnected nanopores within BCP membranes. In addition, the neutral BCP nanopores' surface was modified with positive charges to allow selective diffusion of anions in concentration-gradient cells. By mounting the porous BCP membranes between two aqueous solutions with different concentrations, we studied the BCP-membrane-mediated energy-harvesting performance.

Thick nanoporous matrices of polystyrene nanoparticles and their potential for electrochemical biosensing

Solid-state nanopores with diameter in units of nanometer can be formed by assembling spherical nanoparticles in a dense arrangement. In the current work, the properties of multi-layered highly ordered assemblies of polystyrene nanoparticles were studied, and their feasibility for electrochemical biosensing was probed. These thick matrices were built using a step-by-step deposition technique. Each individual layer of NPs exhibited distinct color which was caused by the thin film interference effect (a color of specific wavelength was characteristic for matrix of specific thickness). The electrochemical characteristics of matrices were investigated with impedance spectroscopy. The impedance spectra of multi-layered matrices exhibited formation of an additional semicircle (RC component additional to the one in a common Randles equivalent circuit). Further, model biosensing based on nanopore blocking was performed using human serum albumin as an antigen and the corresponding monoclonal antibody as an analyte (serology format). Resulting data disfavored the direct employment of the multi-layered matrices for biosensing purposes as the efficiency decreased with increasing thickness of matrices. However, the data revealed highly valuable information about the diffusion and redox processes in the thick nanoporous matrices.

Evaluating the sensing performance of nanopore blockade sensors: A case study of prostate-specific antigen assay

The detection principle of nanopore sensors relies on measuring changes in electrical signal as analyte molecules translocate through a nanoscale pore. There are two challenges with this experimental construct when using nanopores for quantitative sensing with low detection limits in complex samples. The first is getting the analyte to the nanopore in a reasonable time frame and the second is other species in the sample also translocating through the nanopore and generating erroneous signals. We have developed a nanopore blockade sensor that alleviates the limitations of diffusion-limited mass transport and non-specific signals. Antibody-modified magnetic nanoparticles are utilized to deliver analytes of interest extracted from sample to an array of antibody-modified nanopores under a controlled electromagnet, resulting in long-term nanopore blocking events due to the formation of sandwiched immunocomplexes. Herein, this study reports on understanding some of important parameters in determining the performance of nanopore blockade sensing system, where prostate-specific antigen (PSA) is used as a model analyte. We describe the characterization of nanopore blockade sensing of PSA by (1) tuning on/off the electromagnet, (2) varying nanopore number in a nanopore chip, and (3) deploying the sensor in human plasma. Results show that magnetophoresis effectively facilitates active delivery and selective sensing of PSA to the nanopore. Nanopore chips with a larger number of nanopores are shown to receive more nanopore blockades for a given concentration of analyte. Furthermore, identifiable blockade events accounted for successful detection of PSA in plasma, indicate the high specificity of the sensing system.

Embedding molecular photosensitizers and catalysts in nanoporous block copolymer membranes for visible-light driven hydrogen evolution

The integration of molecular photosensitizers and catalysts into functional soft matter supports holds great promise for future energy conversion technologies.

Vertically oriented nanoporous block copolymer membranes for oil/water separation and filtration.

The separation of oil from water and filtration of aqueous solutions and dispersions are critical issues in the processing of waste and contaminated water treatment. Membrane-based technology has been proven as an effective method for the separation of oil from water. In this research, novel vertical nanopores membrane, via oriented cylindrical block copolymer (BCP) films, suitable for oil/water filtration has been designed, fabricated and tested. We used a ∼100 nm thick model poly(styrene-block-methymethacrylate) (PS-b-PMMA) BCP as the active top nanofiltration layer, processed using a roll-to-roll (R2R) method of cold zone annealing (CZA) to obtain vertical orientation, followed by ultraviolet (UV) irradiation selective etch of PMMA cylinders to form vertically oriented nanopores as a novel feature compared to meandering nanopores in other reported BCP systems. The cylindrical nanochannels are hydrophilic, and have a uniform pore size (∼23 nm), a narrow pore size distribution and a high nanopore density (∼420 per sq. micron). The bottom supporting layer is a conventional microporous polyethersulfone (PES) membrane. The created asymmetric membrane is demonstrated to be effective for oil/water extraction with a modestly high throughput rate comparable to other RO/NF membranes. The molecular weight dependent filtration of a water soluble polymer, PEO, demonstrates the broader applications of such membranes.

Facile synthesis of three-dimensional Au/C networks by directly carbonizing nanoporous block copolymers

Porous carbonaceous networks decorated with functional nanoparticles are highly demanded in diverse applications as their good conductivity nature as well as cheap source offers a cost-affordable alternative among numerous options. In this work, we report a new and facile strategy to prepare three-dimensional (3D) Au/C networks comprised of carbonaceous skeletons and tiny gold nanoparticles by directly carbonizing the nanoporous block copolymer films complexed with the gold salts. The robust complexation makes it ease of generating numerous dispersed gold nanoparticles with an average diameter as small as ≈15 nm confined in the carbonaceous frameworks after carbonization. Thus-developed Au/C networks are highly expected to find widespread applications such as catalysis, sensing, etc.

The Importance of Moisture for Brown Rot Degradation of Modified Wood: A Critical Discussion

The effect of wood modification on wood-water interactions in modified wood is poorly understood, even though water is a critical factor in fungal wood degradation. A previous review suggested that decay resistance in modified wood is caused by a reduced wood moisture content (MC) that inhibits the diffusion of oxidative fungal metabolites. It has been reported that a MC below 23%–25% will protect wood from decay, which correlates with the weight percent gain (WPG) level seen to inhibit decay in modified wood for several different kinds of wood modifications. In this review, the focus is on the role of water in brown rot decay of chemically and thermally modified wood. The study synthesizes recent advances in the inhibition of decay and the effects of wood modification on the MC and moisture relationships in modified wood. We discuss three potential mechanisms for diffusion inhibition in modified wood: (i) nanopore blocking; (ii) capillary condensation in nanopores; and (iii) plasticization of hemicelluloses. The nanopore blocking theory works well with cell wall bulking and crosslinking modifications, but it seems less applicable to thermal modification, which may increase nanoporosity. Preventing the formation of capillary water in nanopores also explains cell wall bulking modification well. However, the possibility of increased nanoporosity in thermally modified wood and increased wood-water surface tension for 1.3-dimethylol-4.5-dihydroxyethyleneurea (DMDHEU) modification complicate the interpretation of this theory for these modifications. Inhibition of hemicellulose plasticization fits well with diffusion prevention in acetylated, DMDHEU and thermally modified wood, but plasticity in furfurylated wood may be increased. We also point out that the different mechanisms are not mutually exclusive, and it may be the case that they all play some role to varying degrees for each modification. Furthermore, we highlight recent work which shows that brown rot fungi will eventually degrade modified wood materials, even at high treatment levels. The herein reviewed literature suggests that the modification itself may initially be degraded, followed by an increase in wood cell wall MC to a level where chemical transport is possible.

Nanoporous block copolymer membranes immobilized with gold nanoparticles for continuous flow catalysis

Nanoporous polymers with functionalizable surfaces are desired in the preparation of reactors for continuous flow catalysis.

Nanoporous Block Polymer Thin Films Functionalized with Bio-Inspired Ligands for the Efficient Capture of Heavy Metal Ions from Water.

Heavy metal contamination of water supplies poses a serious threat to public health, prompting the development of novel and sustainable treatment technologies. One promising approach is to molecularly engineer the chemical affinity of a material for the targeted removal of specific molecules from solution. In this work, nanoporous polymer thin films generated from tailor-made block polymers were functionalized with the bio-inspired moieties glutathione and cysteamine for the removal of heavy metal ions, including lead and cadmium, from aqueous solutions. In a single equilibrium stage, the films achieved removal rates of the ions in excess of 95%, which was consistent with predictions based on the engineered material properties. In a flow-through configuration, the thin films achieved an even greater removal rate of the metal ions. Furthermore, in mixed ion solutions the capacity of the thin films, and corresponding removal rates, did not demonstrate any reduction due to competitive adsorption effects. After such experiments the material was repeatedly regenerated quickly with no observed loss in capacity. Thus, these membranes provide a sustainable platform for the efficient purification of lead- and cadmium-contaminated water sources to safe levels. Moreover, their straightforward chemical modifications suggest that they could be engineered to treat sources containing other recalcitrant environmental contaminants as well.