Polyethylenimine Concentration Research Articles

In situ creation of aramid fiber surface coating with polymerizable deep eutectic solvents and their interfacial bonding properties with rubber

AbstractThe coating was created on the surface of aramid fibers (AFs) by solution dip‐coating and in situ UV curable method, using a polymerizable deep eutectic solvent (PDES), dissolved poly(ethylene imine), and poly(ethylene glycol) diacrylate (PEGDA). Fourier transform infrared spectroscopy and thermogravimetry confirmed the successful construction of the coating on the AF surface, which accounted for 12%–17% of the total fiber mass. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) images revealed a 2 μm increase in fiber diameter and a maximum fiber surface average roughness (Ra) of 263.7 nm when the polyethyleneimine content was 0.5% (AF‐PDES‐0.5). Based on these results, H pull‐out samples of fiber/rubber composites were fabricated. The results indicated that the H pull‐out force of AF‐PDES‐0.5 samples increased by 109.74% than that of untreated fiber, and reached 12.92 N of the maximum strength. In summary, the method is simple, rapid, non‐polluting, capable of continuous, and intelligent construction of coatings on the surface of AF. Thus, making it highly promising for application in the field of aviation tires.Highlights Using PDES, green, and low‐carbon preparation processes. Solution dip‐coating and UV reaction for improved reaction speed and workability. Quantitative of interface thickness and modulus using EDS and AFM.

Study on Magnetic and Plasmonic Properties of Fe3O4-PEI-Au and Fe3O4-PEI-Ag Nanoparticles.

Magnetic-plasmonic nanoparticles (NPs) have attracted great interest in many fields because they can exhibit more physical and chemical properties than individual magnetic or plasmonic NPs. In this work, we synthesized Au- or Ag-decorated Fe3O4 nanoparticles coated with PEI (Fe3O4-PEI-M (M = Au or Ag) NPs) using a simple method. The influences of the plasmonic metal NPs' (Au or Ag) coating density on the magnetic and plasmonic properties of the Fe3O4-PEI-M (M = Au or Ag) NPs were investigated, and the density of the plasmonic metal NPs coated on the Fe3O4 NPs surfaces could be adjusted by controlling the polyethyleneimine (PEI) concentration. It showed that the Fe3O4-PEI-M (M = Au or Ag) NPs exhibited both magnetic and plasmonic properties. When the PEI concentration increased from 5 to 35 mg/mL, the coating density of the Au or Ag NPs on the Fe3O4 NPs surfaces increased, the corresponding magnetic intensity became weaker, and the plasmonic intensity was stronger. At the same time, the plasmonic resonance peak of the Fe3O4-PEI-M (M = Au or Ag) NPs was red shifted. Therefore, there was an optimal coverage of the plasmonic metal NPs on the Fe3O4 NPs surfaces to balance the magnetic and plasmonic properties when the PEI concentration was between 15 and 25 mg/mL. This result can guide the application of the Fe3O4-M (M = Au or Ag) NPs in the biomedical field.

Covalent immobilization of β-galactosidase using a novel carrier alginate/tea waste: statistical optimization of beads modification and reusability

β-galactosidase has been immobilized onto novel alginate/tea waste gel beads (Alg/TW) via covalent binding. Alg/TW beads were subjected to chemical modification through amination with polyethyleneimine (PEI) followed by activation with glutaraldehyde (GA). Chemical modification parameters including PEI concentration, PEI pH, and GA concentration were statistically optimized using Response Surface methodology (RSM) based on Box–Behnken Design (BBD). Analysis of variance (ANOVA) results confirmed the great significance of the model that had F value of 37.26 and P value < 0.05. Furthermore, the R2 value (0.9882), Adjusted R2 value (0.9617), and predicted R2 value (0.8130) referred to the high correlation between predicted and experimental values, demonstrating the fitness of the model. In addition, the coefficient of variation (CV) value was 2.90 that pointed to the accuracy of the experiments. The highest immobilization yield (IY) of β-galactosidase (75.1%) was given under optimized conditions of PEI concentration (4%), PEI pH (9.5), and GA concentration (2.5%). Alg/TW beads were characterized by FT-IR, TGA, and SEM techniques at each step of immobilization process. Moreover, the immobilized β-galactosidase revealed a very good reusability as it could be reused for 15 and 20 consecutive cycles keeping 99.7 and 72.1% of its initial activity, respectively. In conclusion, the environmental waste (tea waste) can be used in modern technological industries such as the food and pharmaceutical industry.

Polyethyleneimine-mediated gene transfection in porcine fetal fibroblasts.

Polyethylenimine (PEI) has been explored as an efficient non-viral system for delivering genes to cells; however, there were no protocols for its use in porcine fetal fibroblasts (PFF). Therefore, we compared different concentrations of FITC-PEI (0.625, 1.25, 2.5, 5, 10, 20, 40, or 80 µg/mL) and incubation times (30 min, 1 h, or 2 h). It was observed that the incubation time did not affect the internalization of the PEI-FITC and that 30 min was sufficient to capture the complex. The concentrations higher than 10 µg/mL could reach many marked PFF (>90%). Then, two PEI concentrations were tested, 10 or 40 µg/mL, combined with an N/P of 2 with the pmhyGENIE-5 for 30 min. The percentage of PFF-GFP positive was similar between the PEI concentrations in the evaluation time points (24 h, 48 h, and 72 h). However, 40 µg/mL caused higher membrane damage rates. Thus, it can be concluded that concentrations between 10 - 80 µg/ml of PEI promote high incorporation rates, even in periods as short as 30 minutes. Furthermore, it can be stated that the transfection condition used in Polyplexes 1 (10 µg/mL of PEI and 37.5 µg/mL of pmhyGENIE-5 for 30 min) efficiently produces genetically edited porcine fetal fibroblasts with low cell damage.

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.

Organic Light-Emitting Diodes Laminated with a PEI Adhesion Layer

For the all-solution-processed organic light-emitting diode (OLED), manufacturing the cathode and lowering the work function of the cathode are the main problems limiting their commercialization. This paper reports a two-substrate bonding technology using hot roller lamination with improvement points to solve the existing problems. Ag was used to manufacture the cathode because it is less oxidative compared to Al, which has previously been used conventionally. We tried to use polyethylene imine (PEI), which is conventionally used as an electron injection layer (EIL), as an adhesive layer for the bonding, as it has the quality of being sticky. At higher PEI concentrations, the adhesion strength increased, but the electrical properties deteriorated. Therefore, the PEI wt% was decreased and mixed with polyethylene glycol (PEG), which was reported to lower the work function of the metallic surface. The results showed that the mixed solution of PEI and PEG had good adhesion and electrical properties. The device with an interfacial layer consisting of a 0.1 wt% PEI and 0.01 wt% PEG mixture turned on at 6 V and had a maximum luminance of 2700 cd/m2. The mixed solution layer provided a similar luminous characteristic for single- and double-substrate devices, highlighting the potential of fabricating all-solution-processed OLEDs using the two-substrate bonding technology.

Enhanced separation performance of composite nanofiltration membranes via electrostatic air spray PSS/PEI interlayer

Thin-film composite (TFC) membranes with an interlayer were prepared extensively for desalination, but the hydrophilicity and permeability were not well improved. In this work, a smooth and hydrophilic interlayer was constructed by electrostatic air spray deposition (EASD) of poly (sodium 4-styrenesulfonate) (PSS) and polyethyleneimine (PEI) on the polyethersulfone substrate and an ultra-thin separation layer was prepared using interfacial polymerization of piperazine (PIP) and trimesoyl chloride (TMC) to acquire high-performance composite nanofiltration (NF) membranes. The polymer solution was atomized into tiny particles under a high-pressure electrostatic air spray effect, facilitating the deposition of PSS/PEI with good homogeneity and enabling a denser and smoother interlayer surface. The introduction of PSS/PEI enhanced the hydrophilicity of TFC membranes and increased the repulsion of divalent cations to improve the salt rejection. The impacts of PEI concentration and EASD time on the separation performance of NF membrane were explored. The optimized TFC-3 NF membrane had a permeate flux of 74.5 ± 1.6 L·m−2·h−1 under 0.5 MPa, which was 2.5 times higher than the water flux of conventional TFC-0 membrane, while retaining up to 99.2 ± 0.5 % of Na2SO4. This work provides a prospective strategy to develop high-performance TFC membranes with great extensive progress for seawater purification.

Influence of Polyethylenimine (PEI) in enhancement of microstructure and surface morphology of recycled construction and demolition waste aggregate in concrete by carbonation

This investigation explores the influence of Polyethylenimine (PEI) on the improvement of carbon dioxide (CO2) uptake, surface texture, and pore structure of construction and demolition waste (CDW) through carbonation. The study focuses on the coarser fraction of CDW (10 mm), which is pre-treated with varying concentrations of PEI before being carbonated. The resulting changes in pore structure, mineralogical composition, physical properties, and surface morphologies of the CDW are characterized using various techniques. The study also evaluates the impact of carbonated CDW on compressive strength. The results indicate that PEI modification of CDW enhances carbonation efficiency by reducing pores more effectively than non-treated CDW. This microstructural refinement is possible due to the formation of calcite and its products, facilitated by PEI adsorption into CDW, enhanced CO2 uptake, and formation of calcite products through carbonation. Additionally, PEI modification results in the formation of undulated plate-like structures that enhance surface morphology and compressive strength when used in concrete. The carbonation behavior of PEI-modified CDW in concrete was also investigated by analyzing carbonation depth and pH value. The results reveal that the optimal PEI concentration for enhancing the performance of CDW is 0.2. Overall, the study highlights the potential of PEI modification as an effective approach to improve the properties of CDW and its potential as a sustainable construction material.

Polyethylenimine-based iron oxide nanoparticles enhance cisplatin toxicity in ovarian cancer cells in the presence of a static magnetic field.

Drug resistance in cancer cells is a major concern in chemotherapy. Cisplatin (CIS) is one of the most effective chemotherapeutics for ovarian cancer. Here, we investigated an experimental approach to increase CIS cytotoxicity and overcome cell resistance using nanoparticle-based combination treatments. Polyethylenimine (PEI)-based magnetic iron oxide nanocomplexes were used for drug delivery in genetically matched CIS-resistant (A2780/CP) and -sensitive (A2780) ovarian cancer cells in the presence of a 20 mT static magnetic field. Magnetic nanoparticles (MNPs) were synthesized and bonded to PEI cationic polymers to form binary complexes (PM). The binding of CIS to the PM binary complexes resulted in the formation of ternary complexes PM/C (PEI-MNP/CIS) and PMC (PEI-MNP-CIS). CIS cytotoxicity increased at different concentrations of CIS and PEI in all binary and ternary delivery systems over time. Additionally, CIS induced cell cycle arrest in the S and G2/M phases and reactive oxygen species production in both cell lines. Ternary complexes were more effective than binary complexes at promoting apoptosis in the treated cells. PEI-based magnetic nanocomplexes can be considered novel carriers for increasing CIS cytotoxicity and likely overcoming drug resistance of ovarian cancer cells.

Leaching kinetics and permeability of polyethyleneimine added ammonium sulfate on weathered crust elution-deposited rare earth ores

At present, in-situ leaching of weathered crust elution-deposited rare earth ores (WCE-DREOs) encounter with problems such as long leaching cycles, slow infiltration rate and low product purity. In order to solve the above problems, the conventional leaching agent ammonium sulfate ((NH4)2SO4) was compounded with polymeric surfactant polyethyleneimine (PEI) to form a composite leaching agent. The effects of leaching temperature, PEI concentration, flow rate and pH on leaching kinetics and permeability of rare earths (RE) and aluminum (Al) in orebody were studied. It is found that with temperature increasing, the time required to reach leaching equilibrium for both RE and Al is shortened, the apparent activation energies of RE and Al are 14.79 and 13.45 kJ/mol, respectively, and the leaching processes are in accordance with the outer diffusion control. When the concentrations of (NH4)2SO4 and PEI in the composite leaching agent are 2.0 wt% and 0.4 wt%, the time required to reach leaching equilibrium for RE and Al is about 50% shorter than that using (NH4)2SO4 alone, and the leaching efficiencies of RE are slightly higher than that of Al. Properly increasing the temperature and flow rate of the composite leaching agent can improve the leaching efficiencies of RE and Al, but pH has neglected effects on the leaching efficiencies of RE. At PEI concentrations below 0.4 wt%, the addition of PEI promotes the leaching of RE and Al. In column leaching studies of the WCE-DREO, the addition of 0.4 wt% PEI to the traditional leaching agent (NH4)2SO4 has no impact on the leaching efficiencies of RE. However, it can significantly increase the infiltration rate of WCE-DREO, shortening the leaching time per 10 mL effluent from about 30 min for (NH4)2SO4 leaching system to 20 min for the composite leaching system. The leaching time is shortened by one-third, and the leaching cost is reduced, which can provide theoretical guidance for the development and commercial implementation of novel composite leaching agent for WCE-DREO.

Immobilization of Candida catenulata cells by surface-loading of an amino-functionalized Fe3O4 nanoparticles and its application as the sustainable whole-cell biocatalyst for enzymatic biodiesel production

In this study, the intracellular lipases of Candida catenulata were examined as a whole-cell biocatalyst (WCB) of soybean oil transesterification and obtained a fatty acid methyl ester (FAME) yield of 79.1%. To facilitate the biocatalyst recovery and improve its stability, the WCB was attached to magnetic Fe3O4 nanoparticles activated by a linear structure of polyethyleneimine (PEI) as the multi-amino-functionalized arm. The preparation procedure of the magnetic whole-cell biocatalysts (MWCBs) was optimized by considering the pH during immobilization (X1), the weight ratio of nanoparticles-to-cell (X2), and PEI concentration (X3) using the response surface methodology. The best optimal setting of the variables was determined at X1 of 6.1, X2 of 0.6, and X3 of 0.7 w% with the transesterification activity of 7.6 × 105 IU gbiocatalyst−1 gained a FAME yield of 78.4% after 3 h. The MWCBs showed an improvement in thermal stability where the optimal temperature was shifted from 34C to 38 °C and the deactivation energy was increased from 183.9 kJ mol−1 and 223.6 kJ mol−1 after the immobilization. The MWCBs displayed satisfactory sustainability in the repeated transesterification experiments and maintained 87.3% of the original activity after 10 cycles which was higher than the bare-WCB system with a recovery of 57.4%.

Experimental investigation of PAM/PEI polymer mud for reducing lost circulation in high-temperature formations

Lost circulation is a common and costly problem, especially in high-temperature oil and geothermal wells. Lost circulation materials, including polymeric solutions, are often used to remediate the problem. This study considers using thermoset polymeric gels in water-based drilling fluids as lost circulation materials (LCM) to mitigate the circulation loss in oil and geothermal wells at high temperatures of 150°C (302°F). Two polymers were considered, polyacrylamide (PAM), which serves as the base gel, and polyethyleneimine (PEI), an organic crosslinker. The rheological and sealing property of the PAM/PEI combination as lost circulation material was examined at 150°C (302°F) using a high temperature and high-pressure rheometer and a permeability plugging tester. The results showed the optimum gelation of the mud at 6% PAM and 1.25% PEI solution occurred at 17 minutes. The polymer mud tends to form an elastic-like solid at high concentrations of PAM and PEI. The PAM/PEI polymer mud reduced the fluid loss by 80% during the sealing treatment compared to the conventional LCM treatments with water-based mud. Also, details on effective mixing procedure and testing technique using 3D-printed tapered fracture discs are presented.

Unusual promotion/inhibition effect of polyethylenimine on CO2/CH4 hydrate formation: A potential green chemical additive for CH4-CO2 replacement process

The unusual behavior of a new class of compounds that selectively function as either promoters or inhibitors of gas hydrate formation depending on the process conditions has made their exploration increasingly appealing. In this study, polyethylenimine (PEI) exhibits desirable functionality that may be a candidate for environmentally benign compounds. The present work investigated PEI's thermodynamic and kinetic influence on the formation of CH4 and CO2 hydrates for two PEI concentrations (0.5 and 5.0 mass%) and two PEI molecular weights (25,000 and 750,000 g/mol). The isochoric method was applied to measure the hydrate-liquid water–vapor-three-phase-coexisting (H-LW-V-3PC) phase boundary. PEI is a thermodynamic inhibitor regardless of CH4 or CO2 as a hydrate former, and 0.5 mass% PEI system exhibits the highest average suppression temperatures of 0.25 and 0.62 K, respectively. Kinetic findings, such as induction time, initial hydrate formation rate, and nucleation rate, on the other hand, revealed that PEI could act differently in response to specific hydrate formers. PEI kinetically inhibits CH4 hydrates formation but promotes the formation of CO2 hydrates. This promotion effect is attributed to PEI's high CO2 absorption ability to enhance the solubility of CO2. This unique behavior of PEI presents appealing advantages in the natural gas hydrate exploitation field due to their potential for greater operational flexibility and minimal environmental impact.

Effect of Polyethyleneimine Cationic Surfactant on Morphology and Corrosion Resistance of Electrodeposited Ni-Co-SiC Composite Coatings

Ni-Co-SiC composite coatings were prepared by modified watt-type plating solution with 40 nm SiC particles. The effects of polyethyleneimine (PEI) on the dispersion of SiC nanoparticles and the hardness and corrosion resistance of Ni-Co-SiC coatings were studied. The electrode reaction process was measured by cyclic voltammetry. The results showed that when the PEI concentration was 0.06 g/L, the peak current was the highest. SiC distribution in Ni-Co-SiC coatings was relatively uniform and the coating was flat and dense. With the increase in PEI concentration, the hardness and corrosion resistance showed a trend of increasing first and then decreasing. The hardness and corrosion resistance were at their best with 0.06 g/L PEI. Pretreatment effectively avoided the competitive adsorption of surfactant and other additives on the surface of SiC particles. PEI was preferentially adsorbed on the surface of SiC particles by pretreatment. Steric resistance was formed, which inhibited the agglomeration of nanoparticles and make SiC particles more evenly dispersed into the coating. The hardness was significantly increased by 119.26 Hv, and the corrosion resistance improved accordingly.

Fire protection of wood with an environmentally benign UV-cured polyelectrolyte complex

The use of wood in home and commercial structures has continued to grow in recent years, but its flammability poses a threat to lives and property. Previous attempts to flame retard wood have utilized harmful halogenated chemistries or required complex deposition methods. In this work, a UV-cured flame-retardant treatment is deposited on plywood and natural whitewood through in situ photopolymerization of an anionic phosphate-containing methacrylate, in the presence of cationic polyethylenimine (PEI), to form a polyelectrolyte complex. The influence of PEI molecular weight, PEI and methacrylate concentrations, and deposition time were investigated. The best version of this treatment, deposited in only two steps, renders natural wood and plywood flame retardant without affecting mechanical properties. Cone calorimetry reveals a significant reduction in the total heat release, average heat release rate, and maximum average rate of heat release for both substrates. This environmentally benign and facile system represents a significant advancement for safe and effective flame retardant treatment of wood.

Novel aminated F-Ce nanosheet mixed matrix membranes with controllable channels for CO2 capture

Membrane separation is a novel technology that has been widely studied for efficient CO2 capture. This study aims to synthesize novel porous amino-functionalized nanosheets using PEI (polyethyleneimine) (PEI-F-Ce) and PEI-F-Ce/polyethylene oxide (PEO) mixed matrix membranes (MMMs). PEI-F-Ce nanosheets were prepared via the electrostatic self-assembly method, allowing for the adjustment of both lateral and pore sizes of the nanosheets by varying the PEI concentration. The MMMs loaded with 2 % PEI-F-Ce-2.5 nanosheets exhibit excellent CO2 permeability (641 Barrer) and outstanding CO2/N2 selectivity (70.1). These values surpassed those of pure PEO membranes by 62 % and 53 %, respectively, exceeding the 2019 upper bound. PEI-F-Ce-2.5 nanosheets with a stable pore channel 3.406 nm improved CO2 transport and showed a large CO2 adsorption capacity of 1.32 mmol g−1, leading to enhanced the CO2/N2 reaction selectivity. Moreover, the reversible reaction of CO2 with –NH2 enhanced the CO2/N2 selectivity by 5.1 times at −20 °C, thereby highlighting its potential for cryogenic gas separation applications.

Nanofiltration membranes fabricated by plant polyphenol-intermediated MXene and polyethyleneimine layer-by-layer self-assembly for efficient dye/salt separation

The traditional layer-by-layer (LBL) self-assembly method used to prepare nanofiltration (NF) membranes with polyelectrolytes often suffers from low permeability caused by the restricted free volume of the selective layer. Furthermore, substrate surfaces typically require rigorous chemical treatment with potent acids or bases to achieve the necessary charge for adsorbing the initial polyelectrolyte layer. To address these issues, a green and straightforward aqueous immersion method was utilized in this investigation to form a coating of plant polyphenol tannic acid (TA) on the substrate surface. The TA coating served as an intermediary for the LBL self-assembly of negatively charged 2-dimensional material MXene nanosheets and positively charged polyethyleneimine (PEI), resulting in a well-structured NF membrane. By utilizing a 4-bilayer number, 0.05 mg/mL MXene concentration, 1.0 mg/mL PEI concentration, and PEI molecular weight of 1800 g mol−1, an NF membrane with an ultrahigh pure water permeance of 204.0 L m−2 h−1 bar−1 and 99.9% Evans Blue rejection was produced. Furthermore, the membrane possesses an ultra-high dye/salt separation factor of 758.1, surpassing most of the previously reported data. The innovative plant polyphenol-mediated MXene and PEI LBL self-assembly strategy proposed can be applied not only in NF membrane preparation but also in inspiring the design of advanced MXene composite materials for environmental and energy applications.

Interplay between the Pore Network Modifications and Dynamics of Confined Polyethyleneimine in Self-Assembled Polyethyleneimine–Silica Nanoparticle Microspheres

The CO2 adsorption performance of porous materials loaded with an amine-bearing functionality is determined by the pore network of porous adsorbents and the dynamics of the adsorbed polymeric chains bearing the amine functionality. Herein, we report the modifications in the pore network of evaporation-induced self-assembled microspheres of silica nanoparticles with varying loadings of polyethyleneimine (PEI) using positron annihilation lifetime spectroscopy (PALS) and small-angle X-ray scattering (SAXS). The dynamics of the loaded PEI in the pore network of microspheres have been investigated using temperature-dependent broadband dielectric spectroscopy. PALS investigation confirms microporosity at two different length scales available at the interparticle regions in pristine silica nanoparticle-based microspheres. With PEI loading through the self-assembly process, the pore size and pore volume accessed by PALS are observed to increase up to 20 wt % loading, followed by a decrease due to modification in the clustering behavior of nanoparticles and filling of pores with excess PEI. These variations are highly consistent with the nonmonotonic jamming of silica nanoparticles, as observed from SAXS analysis, arising due to complex interactions between silica nanoparticles and PEI. Both the segmental and localized relaxations of the adsorbed PEI are observed to slow down compared to bulk PEI due to the interactions with silica nanoparticles akin to polymer nanocomposites. The slowing down of the relaxations is consistent with the free-volume variations of the confined PEI determined using PALS. The segmental relaxation time of the loaded PEI in the microspheres varies nonmonotonically with the PEI content. The observations from complementary investigations unequivocally confirm that the packing behavior of silica nanoparticles in the evaporation-induced self-assembled microspheres is controlled by the PEI content. On the other hand, the dynamics of PEI confined within the pore network of the microsphere are determined by the clustering behavior of silica nanoparticles.

All-Solution-Processed OLEDs Using Printed Ag Electrodes and a PEI Bonding Layer

We demonstrated a bonding technology using polyethyleneimine (PEI) as a bonding layer between printed Ag electrodes and an emission material layer (EML) to fabricate all-solution-processed Organic LightEmitting Diodes (OLEDs). We manufactured Ag electrodes on a glass substrate by the screen printing method, which was bonded to another substrate with ITO anodes and an EML layer using a PEI layer. Since the bonding layer needs to have both good bonding characteristics and electrical conductivity, we investigated how both characteristics were affected by some experimental factors, namely, PEI concentration, the thickness of the layer and additives. The bonding strength and the electrical current density were investigated by tensile tests and electron only device (EOD) experiments, respectively. The results showed that at higher PEI concentration the bonding strength reached a higher value, but the electrical current through the PEI layer decreased rapidly with increased PEI layer thickness. When sorbitol was added into the PEI solution, both bonding strength and electrical conductivity were improved, and when 10 wt% of sorbitol was added into 0.1 wt% PEI solution, the device showed an electrical current density of 1,000 mA/cm&lt;sup&gt;2&lt;/sup&gt; and a good bonding strength also. Finally, we manufactured a two-substrate OLED device using the bonding layer and measured the luminance, which revealed that the device turned on at 4 V and the maximum luminance was 7,000 cd/m&lt;sup&gt;2&lt;/sup&gt;. These data, both electrical and optical, demonstrate the potential to fabricate all-solution-processed OLEDs using the two-substrate bonding technology.

A charged nanocomposite membrane via co-deposition of gallic acid and polyethyleneimine-silver for improving separation and antibacterial properties.

Pharmaceuticals have been continuously detected from surface water and groundwater. In order to improve the rejection performance of pharmaceuticals by a nanofiltration membrane (NF), a positively charged membrane was prepared by co-deposition of natural gallic acid and polyethyleneimine on the polyacrylonitrile hydrolysis membrane. Effects of gallic acid concentration, polyethylene imine concentration, reaction time, and the molecular weight of polyethylene imine were documented. The physical and chemical properties of the membrane were also investigated by surface morphology, hydrophilicity, surface charge, and molecular weight cut-off. The optimized membrane had a molecular weight cut-off of about 958 Da and possessed a pure water permeability of 74.21 L·m-2·h-1·MPa-1. The results exhibited salt rejection in the following order: MgCl2 > CaCl2 > MgSO4 > Na2CO3 > NaCl > Na2SO4, while the rejection ability of pharmaceuticals is as follows: amlodipine > atenolol > carbamazepine > ibuprofen, suggesting that the positively charged membrane has enhanced retention to both divalent cations and charged pharmaceuticals. In addition, the antibacterial membrane was obtained by loading silver nanoparticles onto the positively charged membrane, which greatly improved the antibacterial ability of the membrane.