Monomer Solution Research Articles

Development of hydrogen bonding stabilized conjugated carbonaceous polyaryl organic solvent nanofiltration membranes for molecular sieving

This study focuses on a green approach used for the fabrication of a thin film composite organic solvent nanofiltration membrane using aqueous solutions of a pyrrole monomer and iron chloride.

Multifunctional Separator for Li-Ion Batteries Enabling Acid Scavenging and Long Cyclability

The membrane separator is indispensable in lithium-ion batteries (LIBs), electrically isolating the electrodes while hosting liquid electrolyte for facile ion transport. Microporous polyolefin materials, consisting of polyethylene (PE) and/or polypropylene (PP), represent the state-of-the art in separator technology. They offer sufficient mechanical properties, chemical inertness, effective pore sizes <100 nm, porosity ranging from 30-78%, and relatively low costs. However, safety issues associated with thermal shrinkage above 70℃ and poor electrolyte wettability are significant limitations. Replacing these conventional polyolefin separators with multifunctional microporous membranes provides opportunities to address these limitations and other challenges in lithium ion batteries. LiMn2O4 cathodes, for example, attract widespread interest due to the abundance and low cost of Mn, especially in comparison to Co, and reasonable energy densities. However, these cathodes do not provide the calendar and cycle life of the layered oxide cathodes, especially at elevated temperatures (>50°C), due to dissolution of Mn and structural instabilities.1 One of the underlying reasons is the presence of HF in commercial LiPF6-carbonate electrolytes; HF will attack and dissolve the Mn, leading to severe capacity decay, as shown in Figure 1.2 Chemically active multifunctional separator can scavenge HF from the electrolyte, improving the stability of LiMn2O4, but they must be fabricated by low cost, scalable processes without compromising other separator properties.Herein, a multifunctional separator will be described, wherein poly(4-vinylpyridine) (P4VP) is incorporated into separators prepared by polymerization induced phase separation (PIPS). In PIPS, a homogenous solution of difunctional monomers and porogen is polymerized; the difunctional monomers polymerize and crosslink while the porogen phase separates into nanoscale domains. Our previous study employed PIPS to prepare highly porous and thermally stable separators, exhibiting comparable ion transport to conventional Celgard 2500 Polypropylene (PP) separators and negligible thermal shrinkage at 150 °C (digital images in Figure 1).3 Moreover, when incorporated into LIB half cells, these separators enable better electrochemical performance than Celgard 2500 separators due to their reduced thicknesses and superior electrolyte uptake. In the study, P4VP is integrated with the PIPS process to scavenge both HF and PF5 (precursor to HF) through acid-base interactions. A thin layer of P4VP coating was fabricated via initiated chemical vapor deposition (iCVD) process and makes full use of high porosity of separators due to the conformal nature of the coating, increasing the surface area to scavenge the acids. The P4VP-coated PIPS separator enables better capacity retention in Mn-based cathode materials, relative to cells using inert polyolefin separators. The scavenged concentration of HF and transition metal will be compared to validate the HF scavenging property. Post-mortem analysis of the Li anode also confirms the suppression of Mn dissolution and deposition on the anode at elevated temperatures (50°C).

Preparation of Hydrophobic Cryogel Containing Hydroxyoxime Extractant and Its Extraction Properties of Cu(Ⅱ).

Hydrophobic cryogels with monolithic supermacropores based on poly-trimethylolpropane trimethacrylate (pTrim) containing 1-(2-Hydroxyl-5-nonyphenyl)ethanone oxime (LIX84-I) were successfully prepared by a cryo-polymerization technique using organic solvents with freezing points between room temperature and around 0 °C as solvents. The prepared cryogels were characterized in terms of macroscopic shape and porous structure. The cryogels had a monolithic supermacroporous structure and high contents of LIX84-I depending on the added amount of the extractant to the monomer solution. The amount of LIX84-I impregnated in the cryogel had a linear relationship with the added amount of LIX84-I in the monomer solution for cryo-polymerization. Cu(II) in the aqueous solution was immediately adsorbed into the cryogel containing LIX84-I.

C3N4-interlayer-mediated interfacial polymerization of homopolymer nanofiltration membranes for efficient water purification

Interlayered thin film composite (TFNi) membranes have been shown to achieve high-quality polyamide (PA) skin layers with enhanced permeability and selectivity. Herein, we demonstrate the construction of a hydrophilic interlayer by polymeric graphitic carbon nitride (g-C3N4) for optimizing the interfacial polymerization of the nanofiltration membrane. Due to the effective enrichment and the slowed diffuse rate of amine monomer solutions, g-C3N4 modification decreases the thickness of the PA skin layer and increases the electronegativity of membranes. The best TFNi membrane exhibits a high water permeance of 31.82 L m−2 h−1 bar−1, nearly twice as high as that of the membrane without g-C3N4 interlayer, while maintaining a comparably Na2SO4 rejection efficiency. The stronger hydrophilicity and more negatively charged surface of the TFNi membrane effectively retarded membrane fouling, contributing to the high-efficiency removal of harmful drugs from actual surface water, with more than two times higher water flux that of commercialized NF270 membrane. This work provides a facile strategy to synthesize TFNi membranes with great application potential for high-performance nanofiltration.

Preparation and properties of polyester fibers with polyacrylamide hydrogel grafted by UV‐irradiation

AbstractIt is widely recognized that polyester (PET) fibers with swelling properties are necessary for advanced applications of PET fibers in waterproof fabrics. This study presented the UV‐initiated methods to graft polyacrylamide (PAM) hydrogel on the surface of PET fibers. In the one‐step method, PET fibers are impregnated with a mixed solution of the photoinitiator benzophenone (BP) and the monomer acrylalkylamine (AM). Then, the PET fiber was directly exposed to UV light. In the two‐step method, PET fibers were first impregnated with a photoinitiator solution to generate BP radicals. Then, the fibers impregnated with a monomer solution before being grafted by UV light. Both two methods ultimately achieve PAM gelation‐modified PET fibers. The chemical composition and surface structure were detected by Fourier transform infrared spectroscopy and scanning electron microscope. The findings demonstrate that the PAM hydrogel was successfully grafted on the PET fibers through one‐step method or a two‐step method. In addition, the properties of the grafted PET fibers were evaluated by grafting yield, contact angle, and swelling test. The study indicated that the modified PET fibers via a two‐step method exhibited a superior grafting yield up to 29.3% (PET‐2n) and 54% (PET‐2) compared to the one‐step technique (PET‐1). It was shown that the grafting efficacy of PET fibers modified by two‐step method is better than one‐step method. The static contact angles of PET fibers by UV‐Induced were all reduced. For instance, the contact angles of PET‐2n were decreased from 115° to 62.9°; and the two‐step modified PET fiber after acetone cleaning (PET‐2) decreased from 115° to 60°. It was suggested that the hydrophilicity of the modified PET fibers significantly increased. In addition, the research shows that the gelation‐modified fibers were all possessed swelling properties.

An Integrated Asymmetric Wet Adhesive Hydrogel with Gradient Charge Distribution Induced by Electrostatic Field

AbstractAdhesive hydrogels have been applied in biomedical field as an alternative to surgical sutures. However, there still exist rigorous challenges in rough underwater adhesion and asymmetric adhesion of hydrogels, especially applied in wound healing and organ repair in vivo. Herein, a strategy is proposed to prepare integrated hydrogels with asymmetric underwater adhesion capability by forming the asymmetric electrical interface under an electrostatic field. The synergistic effects between catechol and amine and complex coacervation are used to improve the underwater adhesion of hydrogel. Furthermore, by applying an electrostatic field, the cations and anions in solution of monomers are separated to form asymmetric adhesion interfaces. The hydrogel exhibits obvious asymmetric underwater adhesion ability on porcine skin with a strong adhesive strength of 97 kPa on cation side and 25 kPa on the anion side. Animal experiment outcomes reveal that only one side of the asymmetric hydrogel could adhere firmly to the rat liver and the rabbit stomach, while the other side could not effectively prevent postoperative tissue adhesion. The asymmetric distribution of adhesive molecules induced by electrostatic fields will provide a new alternative for designing and adjusting asymmetric adhesives after surgery.

Cooperative supramolecular polymerization of styrylpyrenes for color-dependent circularly polarized luminescence and photocycloaddition

Developing facile and efficient methods to obtain circularly polarized luminescence (CPL) materials with a large luminescence dissymmetry factor (glum) and fluorescence quantum yield (ΦY) is attractive but still challenging. Herein, supramolecular polymerization of styrylpyrenes (R/S-PEB) is utilized to attain this aim, which can self-assemble into helical nanoribbons. Benefiting from the dominant CH-π interactions between the chromophores, the supramolecular solution of S-PEB shows remarkable blue-color CPL property (glum: 0.011, ΦY: 69%). From supramolecular solution to gel, the emission color (blue to yellow-green) and handedness of CPL (glum: –0.011 to +0.005) are concurrently manipulated, while the corresponding supramolecular chirality maintains unchanged, representing the rare example of color-dependent CPL materials. Thanks to the supramolecular confine effect, the [2 + 2] cycloaddition reaction rate of the supramolecular solution is 10.5 times higher than that of the monomeric solution. In contrast, no cycloaddition reaction occurs for the gel and assembled solid samples. Our findings provide a vision for fabricating multi-modal and high-performance CPL-active materials, paving the way for the development of advanced photo-responsive chiral systems.

A novel ZIF-8@IL-MXene/poly (N-isopropylacrylamide) nanocomposite hydrogel toward multifunctional adsorption

Phenols, dyes, and metal ions present in industrial wastewater can adversely affect the environment and leach biological carcinogens. Given that the current research focuses only on the removal of one or two of those categories. Herein, this work reports a novel ZIF-8@IL-MXene/Poly(N-isopropylacrylamide) (NIPAM) nanocomposite hydrogel that can efficiently and conveniently absorb and separate multiple pollutants from industrial wastewater. Ionic liquid (IL) was grafted onto MXene surfaces using a one-step method, and then incorporated into NIPAM monomer solutions to obtain the IL-MXene/PNIPAM composite hydrogel via in-situ polymerization. ZIF-8@IL-MXene/PNIPAM nanocomposite hydrogels were obtained by in-situ growth of ZIF-8 on the pore walls of composite hydrogels. As-prepared nanocomposite hydrogel showed excellent mechanical properties and can withstand ten repeated compressions without any damage, the specific surface area increased by 100 times, and the maximum adsorption capacities for p-nitrophenol (4-NP), crystal violet (CV), and copper ion (Cu2+) were 198.40, 325.03, and 285.65 mg g−1, respectively, at room temperature. The VPTTs of all hydrogels ranged from 33 to 35 °C, so the desorption process can be achieved in deionized water at 35–40 °C, and its adsorption capacities after five adsorption-desorption cycles decreased to 79%, 91%, and 29% for 4-NP, CV, and Cu2+, respectively. The adsorption data fitting results follow pseudo-second-order kinetics and Freundlich models, which is based on multiple interactions between the functional groups contained in hydrogels and adsorbent molecules. The hydrogel is the first to realize the high-efficiency adsorption of phenols, dyes and metal ions in industrial wastewater simultaneously, and the preparation process of hydrogels is environmentally friendly. Also, giving hydrogel multifunctional adsorption is beneficial to promote the development of multifunctional adsorption materials.

Photoinduced step-growth polymerizations of thiophene-carbazole based covalent organic polymer

A novel metal-free photochemical method for the synthesis of porous conjugated polymers was used to investigate the effects of introducing thiophene co-monomer to the carbazole-based polymer, 4,4′-bis(3,6-di(thiophen-2-yl)-9H-carbazol-9-yl)-1,1′-biphenyl (CBP–Th), in terms of its structural, optical, electrochemical and morphological properties. Irradiation of a CBP-Th monomer solution led to the formation of a dark-colored polymer, PCBP-Th, and the role of thiophene on polymerization was investigated, involving electron transfer between CBP-Th and the iodonium ion in the exciplex produced by proton release and radical coupling reactions. The UV–Vis spectra broadened and redshifted due to the elongation of conjugation and solid-state π-π interactions by extra thiophene additive after the polymerization process. The addition of thiophene co-monomer also resulted in decreasing the onset potentials and thus slightly raised HOMO positions determined by the DPV technique. In theoretical calculations, it has been observed that the charge distribution of PCBP-Th at HOMO is over the entire conjugated structure and it has localization in thiophene-thiophene bridges at LUMO. Since the thiophene co-monomer changes the intermolecular distance, the thermal stability of PCBP-Th polymers decreases and accordingly increases the amorphous characters. According to AFM, TEM and SEM images, introducing the thiophene co-monomer led to the formation of larger clusters, resulting in a more pronounced surface texture on both the powders and thin films.

Enhancing oil repellency of electron beam‐grafted polyethylene terephthalate fabric with 2‐(perfluorohexyl) ethyl acrylate monomer via pre‐irradiation

AbstractElectron beam (EB)‐induced graft polymerization is advantageous for the surface modification of fabrics. We investigated the effect of monomer concentration and the addition of alkyl groups on the oil repellency of polyethylene terephthalate (PET) fabrics treated with monomers containing fluoroalkyl groups through EB‐induced graft polymerization via pre‐irradiation. We use 2‐(perfluorohexyl) ethyl acrylate (FEA) and stearyl acrylate (SA(C18)) with long alkyl chains as vinyl monomers to induce reaction with radicals generated from EB irradiation. The weight gain and surface morphology of the PET fabrics change with the FEA monomer concentration. The uniformity of the EB‐grafted PET fabric surface is determined at low monomer solution concentrations. Results of X‐ray photoelectron spectroscopy analysis show that adding 0.1 mol/L of FEA monomer to the EB‐grafted PET fabric yields the highest dodecane contact angle of 93.4° and a surface fluorine concentration of 39.8%. The addition of SA(C18) monomer to the FEA monomer decreases the dodecane contact angle by 77.5° and yields a surface fluorine concentration of 19.1%. EB graft polymerization via pre‐irradiation results in a uniformly treated surface, and stable oil repellency is achieved when using solely the FEA monomer at a lower monomer concentration than that used in a similar irradiation method reportedly previously.

Fabrication of Nano- and Micro-Structured PPy Electrode and its Application to Electroporation to Cell

Electroporation using microstructured electrodes, which generate a localized high electric field, allows molecules (genes) to be introduced into cells; however, there are some technical issues with the fabrication process and material in terms of cytotoxicity and cost. In this study, polypyrrole (PPy), a biocompatible and conductive polymer, is nano- and micro-structured for an electrode of electroporation by electrochemical polymerization. Nano- and micro-scale dots of PPy are generated by a specific pulse waveform of applied voltage in a considerably low concentration of pyrrole (monomer) solution. The conductivity of PPy is changed from 4 to 16 S/cm by dopant concentration with a range of 0.025 M to 0.2 M. It is demonstrated that electroporation using the PPy and ITO electrodes introduce test agent of molecules (Propidium Iodide) into HeLa cells, where 10 and 50 V of pulse voltage is applied. The electroporation using nano-scale dots of PPy electrodes provides a 40% higher introduction rate than that of the micro-dots of PPy electrodes. The introduction rate in electroporation using the nano-scale dots of PPy can be maintained above 95% regardless of the application time of voltage, whereas that of the micro-scale dots of PPy electrodes increases with the application time. It is reasonable to assume that the nano- and micro-structured PPy electrodes are effective in electroporation, as the introduction rates on these PPy electrodes are higher than that of the ITO electrode. However, the cell viability in the electroporation using the nano-scale of PPy electrodes decreases by approximately 30% with application time. Both the introduction rate and cell viability slightly decrease with the conductivity of the PPy electrode; therefore, they are dominated by surface morphologies of the PPy electrode and applied voltage as compared to that of electrode conductivity. Nevertheless, it is demonstrated that the nano- and micro-structured PPy electrodes improve the efficiency of electroporation owing to the locally concentrated electric field.

Electrogeneration of N-substituted polyaniline micro/nanoparticles with potential for energy storage

In the pursuit to develop functionalized polyaniline (PANI) micro/nanoparticles suitable for electrical charge storage, the electrochemical copolymerization of N-(3-sulfopropyl) aniline (AnPS) and N-(2-hydroxyethyl) aniline (AnEtOH) was performed to generate electroactive N-substituted PANI layers directly deposited onto conductive substrates. A particular attention was focused on the impact of the comonomer's molar ratio and pH of the electrolysis solutions on the morphology and electrochemical properties of PANI electrodeposited layers. Thus, four mixtures of the monomers were subjected to electrochemical polymerization in two electrolyte solutions (1 M H2SO4 and acetate buffer solution, pH 4.5) that led to green, homogeneous copolymer deposition layers on the electrode surface. These provided different structural morphologies, that varied from spherical microparticles generated from solution with slightly acidic pH (4.5) to dense, granular morphological features in the case of the deposition layers electrogenerated from 1 M H2SO4. These were characterized in detail by FT-IR and UV–Vis spectroscopies, which confirmed their proposed chemical structure. The electrooxidative polymerization mechanism of the studied N-substituted aniline monomers was evidenced by spectroelectrochemical studies, which highlighted the influence of the monomer's molar ratio and solutions’ pH on the electrolysis process. Moreover, it was demonstrated that the particle dimensions and distributions can be controlled by the comonomer's molar ratio and electrolysis parameters. Considering that the high specific surface area of the obtained PANI micro/nanoparticles can contribute to a better wettability of the polymer molecules with electrolyte ions and their diffusion, the capacitive behaviour of these PANI films was investigated by cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD). The highest areal specific capacitance, of 5.32 mFcm−2, was obtained for the polymer electrogenerated from 1:1 molar ratio of the two monomers, that distinguished by the related polymers through a better ion diffusion at low scan rates and efficient charge transfer at high scan rates.

Preparation and Properties of PDMS Surface Coating for Ultra-Low Friction Characteristics.

Polydimethylsiloxane (PDMS) has excellent physical-chemical properties and good biocompatibility. Thus, PDMS has been widely applied in biomedical applications. However, the low surface free energy and surface hydrophobicity of PDMS can easily lead to adverse symptoms, such as tissue damage and ulceration, during medical treatment. Therefore, the construction of a hydrophilic low-friction surface on the PDMS surface could be helpful for alleviating patient discomfort and would be of great significance for broadening the application of PDMS in the field of interventional medical catheters. Existing surface modification methods such as hydrogel coatings and chemical grafting suffer from several deficiencies including uncontrollable thickness, surface fragility, and low surface strength. In this study, a hydrophilic surface with ultra-low friction properties was prepared on the surface of PDMS by an ultraviolet light (UV) curing method. The monomer acrylamide (AM) was induced by a photoinitiator to form a coating on the surface of the silicone rubber by in situ polymerization. The surface roughness of the as-prepared coatings was regulated by adding different concentrations of 2-acrylamido-2-methylpropanesulfonic acid (AMPS) to the monomer solution, and the coating properties were systematically characterized. The results indicated that the roughness and thickness of the as-prepared coatings decreased with increasing AMPS concentration and the as-prepared coatings had good hydrophilicity and low-friction properties. The Coefficient of Friction (CoF) was as low as 0.0075 in the deionized water solution, which was 99.7% lower than that of the unmodified PDMS surface. Moreover, the coating with a lower surface roughness exhibited better low-friction properties. The results reported herein provide new insight into the preparation of hydrophilic, low-friction coatings on polymer surfaces.

Direct observation of radiation-induced graft polymerization on a polyethylene film

Radiation-induced graft polymerization is widely used in the synthesis of polymeric materials with various functionalities; however, the details of the reaction mechanism are still unresolved. Herein, the initial stage of the graft polymerization reaction was investigated through atomic force microscopy (AFM). We used glycidyl methacrylate (GMA) in methanol (monomer solution) and a high-density polyethylene (HDPE) film with a well-ordered lamellar structure as the substrate. Using polymer film surfaces with a maximum grafting degree of 0.5%, AFM can distinguish between crystalline and amorphous polyethylene (PE) phases as well as a grafted polymer GMA (PGMA) phase. The graft polymerization reaction started from the interface between the crystalline and amorphous PE phases. As the reaction proceeded, the PGMA covered the crystalline PE phase: i.e., the entire surface of the PE film were covered by the PGMA. Further, the crystalline lamellae of the PE film eventually became a scaffold for the formation of aggregates comprising grafted polymer chains alone. The graft polymerization reaction mechanism was explained by comparing the solubility parameters of the monomer solution, substrate, and grafted polymer chains. Understanding the reaction mechanism at a low grafting degree obtained in this study may contribute to enhancing the efficiency of the graft polymerization reaction on any polymeric material.

Influences of Evolution of Pore Structures in Tectonic Coal under Acidization on Methane Desorption.

Experiments on corrosion reactions of pulverized coal with monomeric and polymeric (mixed) acid solutions reveal that monomeric acids are listed in a descending order as HF, HCl, and CH3COOH according to their corrosion effects on tectonic coal collected in Faer Coal Mine (Liupanshui City, Guizhou Province, China). In addition, the optimal mixing ratio of mixed acids is 6% HCl + 6% HF + 3% CH3COOH + 2% KCl. The mineral grains filled in pores in coal samples treated with mixed acid solutions are dissolved, so the porosity increases. The volumes of transition pores and mesopores are obviously affected by acidization, and some transition pores are transformed into mesopores and macropores to form dissolved pores. At the same time, inkbottle-shaped pores reduce, while slit pores or open pores increase. The coal samples after acidization show a higher aromatization degree and an increased relative content of oxygen-containing functional groups, with a generally lower hydroxyl content, so the methane (CH4) adsorption capacity of coal declines, which promotes CH4 desorption. The control effect of pore structures after acidization reactions on CH4 desorption was revealed from perspectives of the diffusion coefficient (Kn), adsorption volume (ω), average pore-throat ratio (PT), and average sinuosity (τav). That is, CH4 molecules in tectonic coal after acidization turn from Knudsen diffusion to transitional diffusion, the adsorption volume of CH4 molecules shrinks, the average pore-throat ratio decreases, and the average sinuosity reduces, which promotes CH4 desorption from tectonic coal.

Janus membranes with simultaneous flux enhancement and fouling/wetting resistance prepared by a modified interfacial polymerization process for membrane distillation

Conventional membrane distillation (MD) membranes are hydrophobic and challenged by severe membrane fouling and wetting. Current surface modification strategies for anti-fouling and anti-wetting purposes, usually complex and time-consuming, often compromise the MD flux. Herein, we propose a modified interfacial polymerization (mIP) approach to fabricate Janus membranes with rapid and robust MD performance. In the mIP process, a dry hydrophobic substrate is first immersed in an oil-phase monomer solution and then in contact with an aqueous monomer solution to trigger the mIP reaction. The as-fabricated Janus membrane (e.g., IP2@PTFE) comprised an ultrathin, underwater oleophobic, and defect-free polyamide (PA) layer and a porous polytetrafluoroethylene (PTFE) substrate. Compared with the unmodified PTFE membrane, the vacuum MD flux of the IP2@PTFE membrane held a 177.4 % increase when tackling a NaCl solution (3.5 wt%) at 60 °C. When the NaCl solution contained sodium dodecyl sulfate (SDS) surfactant or/and mineral oil, the IP2@PTFE membrane exhibited fouling and wetting resistance simultaneously; conversely, severe oil fouling and quick SDS-induced wetting occurred on the pristine PTFE membrane. The mIP process does not require any pretreatment of the hydrophobic substrate, so it is facile and scalable. We believe that this study will facilitate the design of robust MD membranes.

Wearable Biosensor with Molecularly Imprinted Conductive Polymer Structure to Detect Lentivirus in Aerosol.

The coronavirus disease (COVID-19) pandemic has increased pressure to develop low-cost, compact, user-friendly, and ubiquitous virus sensors for monitoring infection outbreaks in communities and preventing economic damage resulting from city lockdowns. As proof of concept, we developed a wearable paper-based virus sensor based on a molecular imprinting technique, using a conductive polyaniline (PANI) polymer to detect the lentivirus as a test sample. This sensor detected the lentivirus with a 4181 TU/mL detection limit in liquid and 0.33% to 2.90% detection efficiency in aerosols at distances ranging from 30 cm to 60 cm. For fabrication, a mixture of a PANI monomer solution and virus were polymerized together to form a conductive PANI sensing element on a polyethylene terephthalate (PET) paper substrate. The sensing element exhibited formation of virus recognition sites after the removal of the virus via ultrasound sonication. A dry measurement technique was established that showed aerosol virus detection by the molecularly imprinted sensors within 1.5 h of virus spraying. This was based on the mechanism via which dispensing virus droplets on the PANI sensing element induced hybridization of the virus and molecularly imprinted virus recognition templates in PANI, influencing the conductivity of the PANI film upon drying. Interestingly, the paper-based virus sensor was easily integrated with a wearable face mask for the detection of viruses in aerosols. Since the paper sensor with molecular imprinting of virus recognition sites showed excellent stability in dry conditions for long periods of time, unlike biological reagents, this wearable biosensor will offer an alternative approach to monitoring virus infections in communities.

Surface-Initiated Zerovalent Metal-Mediated Controlled Radical Polymerization (SI-Mt0CRP) for Brush Engineering.

ConspectusThe surface-tethered polymer brush has become a powerful approach to tailoring the chemical and physical properties of surfaces and interfaces and revealed broad application prospects in widespread fields such as self-cleaning, surface lubrication, and antibiofouling. Access to these diverse functional polymer brushes is highly dependent on versatile and powerful surface-initiated controlled radical polymerization (SI-CRP) strategies. However, conventional SI-CRP typically requires oxygen exclusion, large amounts of catalysts and monomer solution, and a long reaction time, making it time-consuming and sophisticated. When using a two-plate system consisting of an initiator-bearing substrate and a metal plate, we and our collaborators introduced surface-initiated zerovalent metal-mediated controlled radical polymerization (SI-Mt0CRP). In the SI-Mt0CRP setup, a metal(0) plate (Cu, Fe, Zn, or Sn) is placed proximately to an initiator-functionalized substrate and forms a confined polymerization system which considerably simplifies the synthesis of a wide range of polymer brushes with high grafting densities over large areas (up to the meter scale).In comparison to classical SI-ATRP (catalyzed by metal salts), SI-Mt0CRP demonstrates oxygen tolerance, high controllability, good retention of chain-end functionality, and facile recyclability of the metal catalysts (i.e., metal foil/plate). Taking advantage of the confined geometry of the SI-Mt0CRP setup, polymer brushes with various conformations and architectures are easily accessible while consuming only microliter volumes of monomer solution and without complicated operations under ambient conditions. Owing to these attractive characteristics, SI-Mt0CRP has become a versatile technique for functionalizing materials for targeted applications, ranging from the areas of surface science to materials science and nanotechnology.In this Account, we summarize the recent advances of SI-Mt0CRP catalyzed by zerovalent metals (e.g., Cu, Fe, Zn, and Sn) and highlight the intrinsic advantages of the featured experimental setup, compared with the "classical" SI-CRP in which metal salt, powder, or wire is applied. We further discuss the synthetic features and proposed mechanism of SI-Mt0CRP while emphasizing the various external technologies' (including "on water" reaction, galvanic replacement, lithography, and capillary microfluidic) integrated polymerization systems. We also describe structural polymer brushes, including block copolymers, patterned and gradient structures, and arrayed and binary polymer brushes. Finally, we introduce the diverse polymer brushes that have been prepared using these techniques, with a focus on targeted and emerging applications. We anticipate that the discussion presented in this Account will promote a better understanding of the SI-Mt0CRP technique and advance the future development of practical surface brushing.

Immobilization of carbonic anhydrase on poly(ionic liquid) composite membranes for CO2 absorption by gas-liquid membrane contactors

In our current climate crisis, an impressive global effort is being deployed to develop and implement technologies to mitigate CO2 emissions. For instance, CO2 capture and storage/utilization (CCUS) will be fundamental during the energy transition. In the context of CCUS, the enzyme carbonic anhydrase (CA) has gained growing attention because it acts as a green catalyst in CO2 capture by absorption. A few works investigated the preparation of membranes with immobilized CA for CO2 capture by gas-liquid membrane contactors. Although these biocatalytic membranes exhibited improvements in the CO2 capture rate, limited immobilization strategies and carriers have been investigated so far. This work describes the fabrication, characterization, and testing of novel composite membranes with immobilized CA for CO2 capture. The membranes were comprised of a hydrophilic poly(ionic liquid) (PIL) top layer coated on a porous poly(vinylidene fluoride) (PVDF) support. The layer was prepared by in-situ polymerization of an ionic liquid monomer solution cast on the PVDF. CA was easily immobilized on the PIL layer by physical adsorption. The immobilized enzyme's catalytic activity was evaluated to identify the optimum formulation of the PIL layer (monomer and cross-linker concentrations) and immobilization protocol (enzyme concentration in the buffer solution and pH). Despite the immobilization protocol's simplicity, the enzyme was strongly bonded as the enzyme-loaded membranes could be reutilized 10 times while retaining above 90% of their initial activity. These membranes were further characterized by SEM, EDX, ATR-FTIR, TGA, DSC, zeta potential, and water contact angle. Moreover, the biocatalytic composite membranes were tested in a gas absorption set-up to demonstrate their applicability. They showed an increase in the overall mass transfer coefficient with respect to the pristine support by a factor of 2.5, making them interesting candidates for promoting CO2 capture.

Thin film nanocomposite polyamide membrane doped with amino-functionalized graphene quantum dots for organic solvent nanofiltration

Thin film nanocomposite (TFN) organic solvent nanofiltration (OSN) membrane with improved separation performance was fabricated via interfacial polymerization reaction between amine-functionalized graphene quantum dots (af-GQDs) doped aqueous monomer solution of m-phenylenediamine (MPD) and n-hexane solution containing trimesoyl chloride (TMC) monomer. We emphasize the employment of extra-low content for both af-GQDs and MPD, so that we could maximize the function of these nanomaterials and eliminate their aggregation at the same time. The af-GQDs nanomaterials could regulate the interfacial polymerization process and could be strongly anchored in the polyamide film via covalent bonding, hence could prevent their loss while providing more channels for faster solvent penetration. As a result, the optimized OSN membrane, TFN-50, shows a super-smooth surface, with a surface roughness as low as 4.3 ± 0.2 nm, and excellent pure solvent permeances which reach 135.8, 112.7, and 69.8 L m−2 h−1 MPa−1 for methanol, DMF and ethanol, respectively, as well as a very high Rhodamine B (RDB, 479 Da) rejection of up to 99.2%, and an ethanol permeance of 61.4 L m−2 h−1 MPa−1. Furthermore, the TFN-50 OSN membrane still shows excellent filtration performance after being submerged in DMF for 336 h or continuous crossflow filtration with Rose bengal (RB, 1017 Da)/DMF solution for 136 h, demonstrating its excellent solvent resistance.