Polyethyleneimine Molecules Research Articles

Mesoporous Silica-Polyethyleneimine Composites as High-Capacity Adsorbents for CO2 Adsorption: Isotherm and Thermodynamic Analysis

In this study, polyethyleneimine-mesoporous silica composite materials were prepared and the effectiveness of the promising sorbents in adsorbing CO2 was evaluated, along with the impacts of the silica support types (Mesoporous Silica Nanoparticles (MSN) and Mobil Composition of Matter No.48 (MCM-48)), polyethyleneimine (PEI) loading percentages (50 and 70 wt.%), calcination, surface functionalization by alkyl chains (CTMABr), and adsorption temperature (75 and 100 °C). The analysis’s results revealed that the pores of the sorbents were mostly covered with PEI molecules following PEI-functionalization, and the specific surface area and pore volume were also reduced with rising amine content. The highest CO2 adsorption capacities were achieved for UC-MCM-48–50 and UC-MSN–50 at 2.26 mmol/g and 3.31 mmol/g, respectively. The CO2 uptake capacities of CC-MSN–50 and CC-MCM-48–50, composed by dispersing CTMABr surfactant with the calcined materials before incorporating PEI, were remarkably similar to those of non-surfactant functionalized adsorbents. When the temperature’s influence on CO2 adsorption capacity was evaluated, the maximum holding capability adsorbent UC-MSN–50 had a slight increase in adsorption capacity (~ 3.6%), whereas UC-MCM-48–50 had a considerable drop (~ 23.9%) as the temperature elevated to 100 °C. Besides, Langmuir, Freundlich, Dubinin-Radushkevich, and Temkin isotherms were used to model pure CO2 adsorption data, and a thermodynamic study was applied. In conclusion, a low-cost and more beneficial approach, which included less PEI handling and eliminating the calcination step, was implemented to enhance the CO2 sorption capacity of composites of PEI with the long alkyl chain template MCM-48 or MSN silica support materials.

Layer-by-layer assembling boron nitride/polyethyleneimine/MXene hierarchical sandwich structure onto basalt fibers for high-performance epoxy composites

Interfacial adhesion directly affects the mechanical properties of basalt fiber (BF)-reinforced polymer composites. To construct a more superior interphase between BFs and epoxy resin (EP) than a weak interphase of the unmodified BF/EP, we propose a hierarchical sandwich structure consisting of sodium hydroxide–activated boron nitride (BNOH), polyethyleneimine (PEI), and MXene (MX, Ti3C2Tx) through facile layer-by-layer self-assembly. The fabricated BNOH/P/MX sandwich structure (P denoting “PEI”) can synergistically improve the interface adhesion by enhancing the mechanical interlocking and chemical bonding of the composites. When the composites reinforced by BF–BNOH/P/MX subject to the external loading, flexible PEI molecules allow two-dimensional (2D) rigid BNOH and MX nanosheets to slip at the interface by uncurling the molecular chains, dissipating a great amount of energy during the fracture progress. Meanwhile, the hierarchical BNOH/P/MX sandwich structure acts as an excellent interface and possesses multistage gradient modulus and wider thickness, uniformly and efficiently transferring the stress from the EP matrix to BFs. The interfacial shear strength, impact strength, and fracture toughness of BF–BNOH/P/MX-reinforced EP composite are substantially improved by 45.9 %, 60.6 %, and 148.9 %, respectively, compared with bare BF–based composites. This study can provide valuable references and inspirations for designing and constructing high-quality interfaces for high-strength and high-toughness BF structural materials, taking advantage of 2D materials.

Surface functionalized porous MXene (Ti3C2Tx)/Polyethyleneimine membrane for efficient osmotic energy conversion

The development of ion-selective membranes is crucial for achieving efficient osmotic power conversion in reverse electrodialysis system. However, balancing ion selectivity and ion permeability in membranes remains a challenge, limiting improvements in energy conversion efficiency for practical applications. In this study, we develop efficient cation exchange membranes by integrating versatile aromatic hydroxyl groups with MXene nanosheets and polyethyleneimine (PEI) into their lamellar structure. This approach holds promise for achieving non-swelling, high selectivity, and enhanced power density for osmotic energy conversion. The abundance positive surface charge within PEI molecules, combined with the 2D sub-nanochannels of MXene nanosheets, facilitates the biomimetic replication of channel size, chemical groups, and adjustable charge density in the resulting membranes. The fabrication of these membranes is easily achieved through simple hydrothermal, functionalization, and surface-charged techniques, suggesting promising scalability. These membranes exhibit remarkable stability against swelling in aqueous solutions for up to 25 days and demonstrate a high selectivity of 0.95 and a superior output power density of 18.3 W/m2 in artificial river water and seawater.

Coordination polymer derived transition metal phosphide/carbon composites for bifunctional oxygen electrocatalyst

Developing nonprecious electrocatalysts with bifunctional performances for oxygen reduction (ORR) and evolution reactions (OER) remains a crucial challenge in rechargeable Zn-air batteries (RZABs). In this study, we report the synthesis of a three-dimensional (3D) porous N, P-doped carbon-wrapped cobalt phosphide composite (Co2P@3DNPC) via direct calcination of a novel organic/inorganic porous coordination polymer by an in-situ phosphating strategy. DFT calculations demonstrate the intricate interactions occurring during the PEI-directed grinding self-assembly process among Co2+, phytic acid (PA), and polyethylenimine (PEI). Specifically, Co2+ ions initially adsorb onto PEI molecules before integrating with PA to form a 3D coordination polymer matrix. As-fabricated Co2P@3DNPC composite exhibits impressive ORR/OER bifunctional performances, with a half-wave potential of 0.78 V and an overpotential of 1.71 V, respectively. Its bifunctional activities enable a power density of 148.5 mW cm–2 in rechargeable ZABs, with remarkable stability (> 480 h) during a discharge-charge cycle. The interconnected porous structure and embedded Co2P nanoparticles optimize the electrode-electrolyte interfacial contact, boosting energy density and cycle life of as-assembled ZABs. This innovative approach paves the way for efficient, cost-effective production of bifunctional electrocatalysts for RZABs.

Rapid and Large-Scale Synthesis of Chiral and Fluorescent Sulfur Quantum Dots for Intracellular Temperature Monitoring.

The large-scale preparation of fluorescent nanomaterials with laboratory-relevant chemical and optical properties will greatly forward their consumer market applications; however, it still remains challenging. In this work, a universal strategy was developed for the rapid and large-scale synthesis of fluorescent sulfur quantum dots that recently has drawn great attention because of their unique optical characteristics. From the fact that empty 3d orbitals of sulfide species are able to bind with lone-pair π electrons of the heteroatomic groups, many amino-group containing compounds, such as amino acid and polyethylenimine molecules, were exploited to synthesize sulfur quantum dots. This 10 min preparation period endowed sulfur quantum dots with bright blue fluorescence and also chirality. Due to the user-friendly and rapid operation, this strategy can be extended to the large-scale synthesis of sulfur quantum dots with a yield of 16.844 g for one batch of experiment. Moreover, it was found that the sulfur quantum dots exhibited a reversible temperature-dependent luminescent property with a sensitivity of 0.72%/°C, which showed excellent intracellular temperature monitoring capability for inflammation-related disease diagnostics.

Experimental testing and mechanism investigation of amine-functionalized layered vermiculite for CO2 capture

Solid amine adsorbents have attracted significant attention due to their low energy consumption, high selectivity, and environmental friendliness, positioning them as the most promising technology for CO2 capture. However, current adsorbent carrier materials commonly encounter challenges such as expensive costs and inadequate stability. In this study, acid-activated expanded vermiculite carrier (AEV) with a large pore volume and hierarchical pore structure was prepared. Subsequently, a series of functionalized polyethyleneimine (PEI) adsorbents were synthesized and employed in CO2 capture experiments to investigate the impact of PEI loading and temperature on adsorption characteristics. The results showed that the acid-modified expanded vermiculite with a large pore volume structure significantly increased amine loading, while the layered structure network promoted amine dispersion. Under the conditions of 50 wt% PEI loading, the CO2 capture capacity of AEV reached 3.29 mmol/L at 75 ℃. Furthermore, density functional theory was utilized to calculate the adsorption energy and Gibbs free energy change of CO2 and polyethyleneimine molecules. The HOMO and LUMO distributions of CO2 molecules with different polyethyleneimine chains were determined using frontier orbital theory, combined with infrared spectroscopy results confirming the conversion of CO2 into carbamate. Additionally, AEV-PEI50 adsorbent exhibited good stability during 8 cycles of the adsorption process. The obtained results demonstrate that the utilization of layered mesoporous scaffolds offers notable benefits in terms of efficient CO2 capture.

Efficient Approach for Direct Robust Surface Grafting of Polyethyleneimine onto a Polyester Surface during Moulding.

This paper uses a very effective way for surface modification of thermoplastic polymers during moulding. It is based on a grafting reaction between a thin layer of a functional polymer, deposited on a substrate in advance, and a polymer melt. In this paper, a glycol-modified polyethylene terephthalate (PETG) that was brought in contact with a polyethyleneimine layer during fused filament fabrication is investigated. The focus of this paper is the investigation of the reaction product. Grafting was realised by the formation of stable amide bonds by amidation of ester groups in the main chain of a PETG. XPS investigations revealed that the conversion of amino groups was very high, the distribution was even, and the quantity of amino groups per polyester surface area was still very high. The surface properties of the produced polyester part were mainly characterised by polyethyleneimine. The grafting was able to resist several cycles of extraction in alkaline solutions. The stability was only limited by saponification of the polyester. The degree of surface modification was dependent on the molar mass of polyethyleneimine. This could be rationalised, because grafting only occurred with the one polyethyleneimine molecule that is in close vicinity to the polyester surface when both components come in contact. Fused deposition modelling was chosen as the model process with control over each processing step. However, any other moulding process may be applied, particularly injection moulding for mass production.

Carbon dioxide adsorption capacity of porous carbon after polyamine impregnation under different pore structures and temperatures

Composites of polyethyleneimine (PEI) and porous carbon (PC) are effective and reversible CO2 adsorbents. Within these composite materials, the morphologies of PEI in different pore structures significantly influence CO2 capture behaviors, yet little is known about the movement of PEI molecules in PC. In this work, the CO2 adsorption capacity of PEI loaded on PC with different pore structures was investigated. The result shows that the average pore size of 3.63 nm loaded PEI has the maximum CO2 adsorption capacity at 50 ℃. Based on it, we establish a model that the loading of PEI in different pore size PCs for the first time and explain the morphology of PEI in the pore channel. This model displayed the changes in PEI chains and PEI agglomerated cores at different temperatures and pore sizes. In particular, the uptake amount of CO2 in PEI is attributed to the number of amine sites accessible. The PEI agglomerated core formed in smaller pore sizes is smaller and is more susceptible to temperature, thus the PEI agglomerated core exposes more amine sites for CO2 adsorption with increasing temperature. As the PC pore size increases, the PEI agglomerate core also enlarges, leading to greater spatial resistance and therefore exposing fewer amine-based sites when the temperature increases. The investigation of PEI/PC structure–property correlations and adsorption properties provides unique insights that could inform the rational design of better adsorbents.

Hemocompatible polyethylenimine-grafted poly (glycidyl methacrylate) based microspheres for effective endotoxin removal

Endotoxin (also known as lipopolysaccharide, LPS), the major component in the outer cell wall of Gram-negative bacteria, is considered to be a main cause of sepsis. To reduce the mortality of sepsis, adsorbents with positively charged surfaces like polyethylenimine (PEI) are commonly employed to adsorb endotoxins; however, there are hidden dangers in binding stability and hemocompatibility of PEI-grafted materials. Herein, poly (glycidyl methacrylate) microspheres prepared by electro-spraying are chosen as the substrate, the surface epoxy groups are utilized to chemically immobilize PEI molecules. Then, heparin coatings are introduced through electrostatic interaction to obtain composite microspheres as hemoperfusion adsorbent. As a result, the hemocompatibility of the microspheres is significantly improved after the introduction of the heparin coatings. Compared to the microspheres only grafting PEI, the hemolysis ratio has a huge decrease from 4.6% to 1.0%. The adsorption process of the composite microspheres is more consistent with Sips isotherm model with a theoretical maximum endotoxin adsorption capacity of 2659.1 EU/g in normal saline solution. And the microspheres exhibit high endotoxin clearance ratio of 81.3% in static plasma (C0 = 12.6 EU/mL, exceeding critical illness level). In vitro dynamic adsorption experiments also indicate that the microspheres remove 86.6% of endotoxin in septic plasma (C0 = 7.2 EU/mL, exceeding critical illness level) within 1 h. We hope that the composite microspheres could have good application potential as an efficiency endotoxin adsorbent in sepsis treatment.

Closing the Gap between Experiment and Simulation─A Holistic Study on the Complexation of Small Interfering RNAs with Polyethylenimine.

Rational design is pivotal in the modern development of nucleic acid nanocarrier systems. With the rising prominence of polymeric materials as alternatives to lipid-based carriers, understanding their structure-function relationships becomes paramount. Here, we introduce a newly developed coarse-grained model of polyethylenimine (PEI) based on the Martini 3 force field. This model facilitates molecular dynamics simulations of true-sized PEI molecules, exemplified by molecules with molecular weights of 1.3, 5, 10, and 25 kDa, with degrees of branching between 50.0 and 61.5%. We employed this model to investigate the thermodynamics of small interfering RNA (siRNA) complexation with PEI. Our simulations underscore the pivotal role of electrostatic interactions in the complexation process. Thermodynamic analyses revealed a stronger binding affinity with increased protonation, notably in acidic (endosomal) pH, compared to neutral conditions. Furthermore, the molecular weight of PEI was found to be a critical determinant of binding dynamics: smaller PEI molecules closely enveloped the siRNA, whereas larger ones extended outward, facilitating the formation of complexes with multiple RNA molecules. Experimental validations, encompassing isothermal titration calorimetry and single-molecule fluorescence spectroscopy, aligned well with our computational predictions. Our findings not only validate the fidelity of our PEI model but also accentuate the importance of in silico data in the rational design of polymeric drug carriers. The synergy between computational predictions and experimental validations, as showcased here, signals a refined and precise approach to drug carrier design.

Structurally robust cellulosic triboelectric materials under high moisture conditions for self-powered sensing

Eco-friendly cellulosic fibers-based triboelectric nanogenerators (TENGs) are enormously and increasingly demanded for self-powered flexible electronics. However, under high moisture conditions (e.g. sweat, sailing and rain day), the mechanical behaviors of hydrophilic paper were severely reduced due to the weak wet strength and the cellulosic paper-based sensors were easily destroyed under external force, leading to the device failure and invalid signal acquisition. Herein, an industrial-friendly polyethylenimine (PEI)-assisted pulping strategy was developed to produce advanced cellulosic papers, which possessed reinforced wet strength and tribopositive performance. During pulping procedure, the cationic PEI molecules could be quickly in situ bonded onto the surface of fibers under electrostatic interaction and the interfacial interaction between fibers was significantly enhanced through the formation of hydrogen bonds between the amino groups on PEI and the hydroxyl groups on cellulose fibers. The wet strength was significantly enhanced from 1.93 MPa for pristine paper to 8.33 MPa for cellulose/PEI1.5% with an enhancement of 4.32 times. Moreover, originating from the enhanced dielectric behaviors upon the introduction of PEI, the optimized cellulose/PEI1.5% TENG delivered the maximum VOC of 157.3 V, ISC of 3.47 μA, QSC of 42.73 nC and instantaneously maximum power density of 145.93 mW·m−2. Our findings proposed a new perspective for fabricating high-performance tribopositive cellulosic materials that withstand high humid conditions.

Integrating with a tough framework and efficient self-healing behavior based on a flexible polymer skeleton for Si anode binders in lithium-ion cells

As a prospective and efficient strategy to address the volume expansion of the Si nanoparticles, the binder plays an increasingly significant role in the Si anode of lithium-ion batteries. Based on the inspiration of natural physics and cross-linked networks, a functional (named polyacrylic acid-citric acid-polyethyleneimine) binder that is similar to a flexible polymer skeleton integrated with a tough framework and efficient self-healing behavior is designed to achieve long cycling stability for Si anodes. The cross-linked network can be stabilized by the amide bonds, formed by polyethyleneimine (PEI) and polyacrylic acid (PAA). Based on this, citric acid (CA) can be added to form multiple hydrogen bonds, whose carboxyl groups can also establish a more reversible cross-linked network with Si particles. Then, PEI and CA molecules can connect with PAA to form a “rigid and flexible” structure. The expansion stress of Si nanoparticles is relieved by the protective buffer layer built by the addition of PEI and CA molecules. In addition, PAA, PEI, and CA work together to solve the problem that the action of CA and PAA alone cannot perform well under large currents. Hence, this water-based binder with a three-dimensional cross-linked network structure with self-healing ability has better performance during cycling: at a current density of 0.2C, it still has a capacity of 2017.4 mAh·g−1 after 200 cycles, with a capacity retention rate of 80.7 % (1745.3 mAh·g−1, 300 cycles, a capacity retention of 74.9 %).

Interparticle interaction-dependent jamming in colloids: insights into glass transition and morphology modulation during rapid evaporation-induced assembly.

Understanding the role of interparticle interactions in jamming phenomena is essential for gaining insights into the intriguing glass transition behavior observed in atomic and molecular systems. In this study, we investigate the jamming behavior of colloids with tunable interparticle interactions during evaporation-induced assembly (EIA). By manipulating the interaction among charged colloids using cationic polyethyleneimine (PEI) through electro-sorption and subsequent free polymer induced repulsion, we observe distinct jamming behavior in silica colloids during EIA, depending on the interparticle interactions. Silica colloids with strong repulsive interactions exhibit a repulsive colloidal glass state with a volume fraction of silica colloids in supraparticle ϕ ∼ 0.70. On the other hand, PEI-mediated attractive interactions among silica colloids lead to an attractive colloidal glass phase with a significantly lower ϕ ∼ 0.43. Free polymer induced repulsion of colloids at higher PEI concentration once again results in a repulsive glassy state with ϕ ∼ 0.61. Furthermore, we revealed that interparticle interactions not only influence the jamming behavior but also play a significant role in shaping the morphology of self-assembled structures during EIA, and the assembled structure undergoes a morphological reentrant transition from a doughnut-like shape to a spherical form and again back to a doughnut-like configuration. Jamming-dependent evolution of micropores and dynamics of the confined PEI have been probed using positron annihilation lifetime spectroscopy (PALS) and broadband dielectric spectroscopy (BDS). PALS reveals distinct variations in the micropores of the supraparticles with different PEI loadings, confirming the impact of jamming on the evolution of the micropores within the supraparticles. BDS measurements uncover non-monotonic dynamics of PEI molecules confined in the evolved pore network. It is revealed that the reentrant jamming behavior of colloids, modulated by PEI, holds profound significance for the long-term stability of supraparticles.

Synthesis and characterization of the porous activated carbon from end-of-life tire pyrolysis for CO2 sequestration

This research aims to synthesize and characterize the CO2 adsor+bent from waste tire (WT) as a precursor to produce porous carbon adsorbent material using a combination of thermal (pyrolysis, 600–700 °C) and chemical (H3PO4 and KOH) methods. The derived fine black powder was impregnated by 10–50 wt% polyethyleneimine (PEI) to produce porous carbon material (PEI-PCM) for evaluation of the performance of CO2 adsorption under TGA (micro-scale system). To observe the PEI loading and relevant CO2 capture selectivity characteristics, X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) method, and Fourier transform infrared spectrometry (FT-IR) were carried out. The XRD pattern showed the main phase of amorphous carbon, graphite, and some impurities (ZnS). Type II adsorption isotherm is related with reducing of the specific surface area and pore volume from 78 m2·g−1 to 25.26 m2·g−1, 0.45 cm3·g−1 to 0.23 cm3·g−1, respectively. The FT-IR spectra indicated the bending of primary and secondary amine which belonged to PEI molecule. It can be concluded that PEI-PCM properties such as, pore-size distribution, pore volume and surface functional groups supported CO2 adsorption capability following surface structure modification. The 50 wt% PEI-PCM-P showed good adsorption capacity of 53.81 mg·g−1 at temperatures of 75 °C. As a result, the PEI-PCM was successfully developed for CO2 absorption application. This work can help mitigating the challenge of disposal of WT and realization of the bio-circular-green economy (BCG model).

Ionic liquid‐induced deep grafting of polyelectrolyte to reform polyamide layer for antifouling nanofiltration membrane

AbstractSurface grafting has been widely used to tune hydrophilicity and chargeability of nanofiltration membranes for reducing membrane fouling potential. However, surface grafting typically leads to a significant pore narrowing and resultant permeability loss, and monocharged surface still struggles to resist mixed foulants with different charges. Herein, ionic liquid (IL)‐ethanol (EtOH) solution containing polyethyleneimine (PEI) is used to rearrange the nascent polyamide layer. The high affinity of IL to the PA layer and the low diffusion steric hindrance of EtOH contribute to the polyamide swelling and PEI deep grafting, during which the “self‐regulation” effect (larger pores would be filled with more PEI molecules) narrows the pore size distribution and enhances hydrophilicity. The nearly charge‐neutral and smooth separation layer shows impressive antifouling capacity to hydrophobic macromolecules and mixed charged molecules, along with long‐term operating stability for real wastewater treatment. This study emphasizes the importance of solvent properties on the membrane grafting behavior.

PEI-Schiff base-modified mesoporous silica materials SBA-12, 15 and 16 for toxic metal ions capture (Co(II), Ni(II) and Cu(II)): Effect of morphology, post-synthetic modification and kinetic study

A series of SBA materials (SBA-12, SBA-15, and SBA-16) with polyethyleneimine (PEI) and its Schiff base variants with salicylaldehyde-modified samples (PS) have been successfully prepared and characterized. The synthesized materials were investigated by infrared spectroscopy (FT-IR), and quantification of the organic part coated on the surface was studied using thermogravimetric analysis (TGA). Nitrogen adsorption/desorption analysis at − 196 °C (N2), bright field scanning transmission electron microscopy (BF-STEM) and small angle X-ray scattering (SAXS) measurements were used to study textural properties, structure and morphology. Confirmation of heavy metal ions capture in pores of prepared materials was proved by X-ray fluorescence analysis (XRF), and nitrate anions were confirmed by FT-IR spectroscopy. Kinetic studies were performed by conductometric analysis (CA) and showed that the mathematical models could be applied to adsorption processes with a non-linear decreasing trend. This trend appeared in PS-modified SBA systems and some non-modified samples. The best overall adsorption properties were observed for material SBA-12 and its modified types. In this case, material SBA-12-PS can trap 54.38 mg g−1 of Cu(NO3)2 or 18.42 mg of Cu(II) ions, 112.84 mg g−1 of Ni(NO3)2 corresponding to 36.24 mg of Ni(II) cations, and 39.56 mg g−1 of Co(NO3)2 representing 12.74 mg of Co(II) ions. Non-modified materials show morphological effects where 2D ordered pores with hexagonal symmetry and the biggest mesopores (5.5 nm) have the best overall results in adsorption capacity of metal ions (Cu(II): 11.95 mg g−1) calculated from pseudo-second order. SBA-12 with a cubic framework and 3D ordered pores (3.8 nm) has a lower adsorption capacity than SBA-15 (Cu(II): 7.85 mg g−1), and SBA-16 with the smallest spherical pores (under 2 nm) showed the lowest overall adsorption capacity (Cu(II): 4.65 mg g−1). Kinetic rates of non-modified samples have opposite trend SBA-12 (Cu(II): 0.009 mg g−1 min−1) > SBA-15 (Cu(II): 0.002 mg g−1 min−1) > SBA-16 (Cu(II): 0.001 mg g−1 min−1). In the case of SBA-16, small pore entrances have a negative effect on the kinetic rate. For modified samples, SBA-12 with the largest surface area (896 m2 g−1) provides more space for binding of polyethyleneimine molecules (and also salicylaldehyde), which affects the best results in ion capture (Cu(II): 16.64 mg g−1). Bigger mesopores give more adsorption capacity, but capillarity makes the kinetic rate slow. SBA-16, with tiny entrance mesopores, has the lowest kinetic rate and adsorption capacity. This phenomenon was also observed in cobalt(II) adsorption, and similar results were obtained in nickel(II) adsorption. Kinetic studies point to two types of mechanisms given by the pseudo-second-order model in the case of non-modified materials, and Elovich kinetic model describes chemisorption at modified samples. These mechanisms are influenced by the significant effect of intraparticle diffusion, described by the Weber-Morris model.

Super-Resolution Fluorescence Imaging for Semiconductor Nanoscale Metrology and Inspection.

The increase in the number and complexity of process levels in semiconductor production has driven the need for the development of new measurement methods that can evaluate semiconductor devices at the critical dimensions of fine patterns and simultaneously inspect nanoscale contaminants or defects. However, conventional optical inspection methods often fail to resolve device patterns or defects at the level of tens of nanometers required for device development owing to their diffraction-limited resolutions. In this study, we used the stochastic optical reconstruction microscopy (STORM) technique to image semiconductor nanostructures with feature sizes as small as 30 nm and detect individual 20 nm-diameter contaminants. STORM imaging of semiconductor nanopatterns is based on the development of a selective labeling method of fluorophores for a negative silicon oxide surface using the charge interaction of positive polyethylenimine molecules. This study demonstrates the potential of STORM for nanoscale metrology and in-line defect inspection of semiconductor integrated circuits.

Selective layer reconstruction of deteriorated polyamide membrane by surface chemical deposition for desalination performance restoration and simultaneous antifouling and anti‑chlorine

This work focused on salt rejection restoration and simultaneous anti-fouling and anti‑chlorine functionalization of partially deteriorated polyamide-based reverse osmosis membrane by surface chemical deposition of tannic acid (TA) followed with polyethyleneimine (PEI). TA molecules were chemically deposited onto membrane surface with glutaraldehyde as bridging and cross-linking agent. The deposited TA molecules were then employed for sequential chemical deposition of PEI molecules through Schiff base reaction under hot alkaline condition. Restoration process was optimized and its influences on membrane physico-chemical properties were systematically studied. Under desired restoring conditions, deposition of TA molecules was found to recover NaCl rejection from 93.2 % to 96.5 %, the sequential deposition of PEI molecules further improved NaCl rejection up to 98.6 %. The depositions of TA and PEI were found to greatly improve membrane surface hydrophilicity and make the membrane hardly charged under neutral pH. The fouling resistance of restored membrane was better than the new polyamide based membrane for its excellent hydrophilicity and surface brushes induced by the PEI molecules grafted. Chlorination tests proved that the antioxidant structures of the deposited TA and PEI molecules endowed the restored membrane with better chlorine stability compared to the new polyamide membrane.

Adsorption of Polyethyleneimine on Fine Arsenopyrite and the Effect on Its Xanthate Flotation

Effective flotation of fine particles is a problem for mineral processing. In this paper, a flocculant mostly used in heavy metal ion treatment was used in an arsenopyrite flotation system. The adsorption behavior and flotation performance of PEI on the xanthate flotation of arsenopyrite were investigated through zeta potential and adsorbed amount measurements, XPS and size distribution detections, and micro-flotation tests. Zeta potential results showed that the adsorption of 40 mg/L polyethyleneimine (PEI) caused an increase in the zeta potential of arsenopyrite, and had only a slight depression on the further adsorption of SBX, which was further confirmed by the results of the adsorbed amount measurements. However, when the dosage of PEI was 150 mg/L, the adsorption of SBX was strongly depressed. This was because moderate PEI only bridged different arsenopyrite particles, and most of the active sites for the SBX adsorption were still exposed; when PEI was in excess, the mineral particles would be covered so that there were not enough active sites for SBX adsorption. Fe and As on the mineral surface were the adsorption sites for the PEI molecules, which were resolved from the chemical shifts in the As/Fe peaks of the XPS spectra. PEI can increase particle size, and moderate PEI dosage can make the particle size suitable for flotation with SBX where bridging and hydrophobic effects take place. The flotation results showed that −20 μm arsenopyrite particles had poor flotation recovery with the SBX collector alone, but when they were treated with 40 mg/L PEI, the recovery largely increased. PEI can serve as an effective flocculant for the flocculation flotation of fine arsenopyrite. A comparison model, showing the possible interactions among reagents, particles, and bubbles in the pulp with different PEI dosages, is proposed.

Porous vermiculite membrane with high permeance for carbon capture

Two-dimensional (2D) membranes with interlayer nanochannels hold great promise for CO2 capture. However, the permeance is often limited by the high transmembrane resistance primarily caused by the tortuous interlayer diffusion pathway. Here, a facile method for preparing 2D porous vermiculite (PVMT) membranes is presented to boost CO2 transport by increasing the number of additional through-plane channels. The pristine vermiculite (VMT) nanosheets were treated with acid etching to generate nanopores by dissolving metal cations thereon. The resulting porous nanosheets were co-assembled with polyethyleneimine (PEI) molecules by vacuum-assisted self-assembly to fabricate PVMT-PEI membranes. The PEI molecules regulate the channel size to elevate the diffusion of CO2 and their amino groups afford affinity toward CO2 to increase its dissolution, thus intensifying the facilitated transport mechanism. The optimized PVMT-PEI membrane shows high performance with CO2 permeance of 568 GPU and CO2/CH4 selectivity of 27.6, which is 165% and 94% higher than pristine VMT membrane. In addition, the PVMT-PEI membranes exhibit good long-term operation stability.