Polyethylenimine Concentration Research Articles

Facile preparation of a polymer-ZnO composite colloid as an electron transport layer and its effects on inverted polymer solar cells

A polymer-ZnO colloidal solution was prepared as the organic-inorganic composite electron transport layer of inverted polymer solar cells (i-PSCs) by successive modification of ZnO particles with organic dispersant and polyethyleneimine (PEI), which offers an alternative to previously used complicated processes such as high temperature annealing or multi-layer coatings. The modification of ZnO surfaces with 2-(2-methoxyethoxy) acetic acid (MEA) provides colloidal stability and prevents aggregation of ZnO particles after adding PEI into the ZnO colloidal solution. The amount of incorporated PEI was increased to ~10 wt%, and the cell performance parameters of Jsc and fill factor (FF) were enhanced proportional to PEI content because of its contribution in decreasing the work function of ZnO ETL. By fabrication of i-PSCs with the modified ZnO ETL, the power conversion efficiency (PCE) was increased by ~40% from 5.10% to 7.51% in the ITO/ETL/PV-D4610:PC60BM/MoO3/Ag structure. The multi-functionalized ZnO ETL provides a more facile process for preparation of an organic-inorganic composite ETL to improve the performance of i-PSCs.

Electrolyte Additives for Controlling Roughness of Copper Electrodeposits Formed in Deep Eutectic Solvents

Due to their wide electrochemical stability window, non-toxicity, and highly solubility for metal salts, deep eutectic solvents (DESs) are attracting attention as new class of electrolytes for electrodeposition and energy storage applications. However, due to their viscous nature, DESs impose transport limitations implying rough or dendritic morphology of electrodeposits formed in them. In the present work, we investigated roughness evolution during copper electrodeposition in a DES containing choline chloride and ethylene glycol in a 1:2 molar ratio (ethaline). Cuprous chloride was added to the DES as the metal precursor. Further, polyethyleneimine (PEI) – a common electrolyte additive used in electrodeposition from aqueous media – was added to ethaline and its effects on roughness evolution were investigated. Steady-state polarization measurements confirmed that PEI suppresses copper electrodeposition kinetics. This manifests into micro-scale leveling of deposits and thus suppression of roughness amplification during electrodeposition, which was confirmed electrochemically as well as using optical profilometry. Effects of PEI concentration on electrochemical behavior and roughness suppression were investigated. Specifically, hysteretic response during cyclic voltammetry was observed under certain conditions. Implications of the PEI-induced hysteresis on suppression of roughness in high-efficiency rechargeable batteries will be discussed.

Hysteresis effects and roughness suppression efficacy of polyethylenimine additive in Cu electrodeposition in ethaline

Deep eutectic solvents (DES) are environmentally-friendly electrolytes that are gaining interest for electrodeposition and energy storage applications. In these applications, metal electrodeposits with smooth, non-dendritic morphology are desired and thus effective strategies for suppressing roughness evolution are critically needed. A commonly employed and rather effective strategy for suppressing roughness evolution in metal electrodeposition is the use of electrolyte additives; however, the availability of such additives in DES electrolytes is limited and so is the understanding of the mechanisms through which additives suppress roughness amplification in DES media. In the present contribution, we demonstrate that polyethylenimine (PEI) is an effective electrolyte additive that suppresses roughness evolution during Cu electrodeposition in ethaline DES. PEI, due to its adsorption–deactivation properties, exhibits a unique hysteresis response during voltammetric studies of Cu electrodeposition – this response is analyzed using a mathematical model incorporating the relevant PEI transport, surface adsorption and deactivation processes. The model provides guidelines for selection of optimal conditions (e.g., PEI concentration) for effective suppression of roughness amplification in Cu electrodeposition.

Ionic Self-Assembled Luminescent Nanospheres from Cationic Polyelectrolyte and Eu-Containing Polyoxometalate.

Using the ionic self-assembly (ISA) strategy to combine Eu-containing polyoxometalates (Eu-POMs) and organic molecules mainly through noncovalent electrostatic interactions can protect Eu-POMs from solvent quenching of luminescence and enhance their processability. For this reason, a cationic polyelectrolyte, branched polyethyleneimine (PEI), and a Eu-POM, Na9(EuW10O36)·32H2O (EuW10), were used here to construct luminescence-enhanced spherical aggregates with diameters ranging from 50 to 200 nm. At a fixed concentration of EuW10, the phase behavior and luminescence properties of the mixture could be modulated by the PEI concentration. Such ISA-induced aggregates could effectively shield water molecules and result in better photophysical properties. Compared to bare EuW10, the absolute quantum yield and lifetime of luminescence for aggregates increased 10 and 5 times, respectively. Meanwhile, the sensitivity of the EuW10 coordination structure to the environment made it possible for obtained aggregates being used to detect either copper cations or permanganate anions due to their strong specific quenching effects to luminescence. Such a new type of luminescent soft material not only provided a reference for exploring the luminescence enhancement mechanism of lanthanide through self-assembly in aqueous solution but also exhibited potential in detection by luminescence analysis.

Transparent ultra-thin silver electrodes formed via a maskless evaporation process for applications in flexible organic light-emitting devices

Abstract We have fabricated flexible, transparent, ultra-thin silver (Ag) electrodes by using a maskless deposition process and applied them to organic light-emitting devices (OLEDs). A selective ultraviolet/ozone (UV/O3) treatment was performed on the polyethylenimine (PEI) polymer layer, which contained amine groups and was coated onto a silicon substrate, in order to form an electrode pattern. An ultra-thin Ag film was deposited in vacuum on the UV/O3-treated substrate without a mask, resulting in the formation of a flexible, transparent, ultra-thin Ag electrode pattern. The optimum PEI concentration and the optimum UV/O3 treatment time for the formation of flexible, transparent, Ag electrode patterns were determined from their sheet resistances, optical transmittances, Fourier-transform infrared spectra and X-ray photoelectron spectra. The sheet resistance of the ultra-thin Ag electrode transferred to an epoxy substrate changed within 5% only when the bending diameter of curvature and the number of bending cycles were 5 mm and 3000, respectively. The current density and the luminance of an OLED with a flexible, transparent, ultra-thin Ag electrode deposited on an epoxy substrate were larger than those of an OLED with an indium-tin-oxide (ITO) electrode formed on a polyethylene naphthalate substrate. We have confirmed that the flexible, transparent, ultra-thin Ag electrodes hold promise for use in the fabrication of flexible OLEDs.

Interaction among branched polyethylenimine (PEI), sodium dodecyl sulfate (SDS) and metal cations during copper recovery from water using polymer-surfactant aggregates

The application of polymer–surfactant aggregates (PSAs) to recover heavy metal ions from water is a novel treatment process for aqueous metallic effluents. To better employ this strategy, branched polyethylenimine (PEI), sodium dodecyl sulfate (SDS) and copper ions were selected to investigate their interaction in water and to improve the recyclable PSAs process for metal removal and recovery. Electrostatic association between PEI and SDS caused the formation of PSAs, and the addition of SDS to a partially protonated PEI solution caused a pH increase; however, re-dispersal of PSAs could be achieved via an increase in pH. Precipitation of PSAs depended on pH, SDS/PEI concentration ratio and the total concentration of PEI; the optimal SDS/PEI ratio decreased as pH increased, and a higher concentration of PEI showed a greater potential to precipitate. PEI formed a strong complex with Cu2+, with the most stable complex at a PEI/Cu chelation ratio of 4. Acidification decreased the chelation capacity of PEI to Cu2+, because of the competition from protons for amino groups. Complexation with Cu2+ in turn reduced the proton buffer capacity of PEI in a non-acid solution. The removal of Cu2+ increased by increasing the total PEI concentration, or by increasing pH from 1 to above 4. Ionic strength and hardness had no marked effect on Cu2+ removal using the PSAs process. Following the initial interaction among PEI, SDS and Cu2+, the Cu2+ could then be released from the PSAs by acidification and the reuse of the PSAs material could be achieved by alkalization. Copper removal and recovery were still up to 98 % and 88 % after three reuse cycles of the PSAs process, respectively.

In Vitro Corrosion Behavior of Biodegradable Iron Foams with Polymeric Coating.

Research in the field of biodegradable metallic scaffolds has advanced during the last decades. Resorbable implants based on iron have become an attractive alternative to the temporary devices made of inert metals. Overcoming an insufficient corrosion rate of pure iron, though, still remains a problem. In our work, we have prepared iron foams and coated them with three different concentrations of polyethyleneimine (PEI) to increase their corrosion rates. Scanning electron microscopy (SEM) coupled with energy dispersive X-ray analysis (EDX), Fourier-transform infrared spectroscopy (FT-IR), and Raman spectroscopy were used for characterization of the polymer coating. The corrosion behavior of the powder-metallurgically prepared samples was evaluated electrochemically using an anodic polarization method. A 12 weeks long in vitro degradation study in Hanks’ solution at 37 °C was also performed. Surface morphology, corrosion behavior, and degradation rates of the open-cell foams were studied and discussed. The use of PEI coating led to an increase in the corrosion rates of the cellular material. The sample with the highest concentration of PEI film showed the most rapid corrosion in the environment of simulated body fluids.

Evaluation of a novel polyamide-polyethylenimine nanofiltration membrane for wastewater treatment: Removal of Cu2+ ions

Abstract This paper describes a novel approach for enhancing membrane technology for the removal of heavy metal cations in contaminated waters. A simple method of forming a positively charged polyamide (PA) nanofiltration (NF) membrane has been developed by attaching a layer of hyperbranched polyethylenimine (PEI) to the PA surface, involving the linking of PEI amino groups to the PA surface carboxyl groups. The nature of the PEI modified PA membrane, in terms of surface morphology, zeta potential and hydrophobicity was found to depend on the PEI molecular weight (MW), and the PEI concentration and membrane exposure time during preparation. In turn, the nature of the modified membrane determined its performance in terms of hydraulic flux and metal ion rejection. In tests using a model solution of 5 mg/L Cu2+ and a 70,000 MW PEI membrane the Cu rejection was >90%, with only a modest reduction in flux compared to blank water. The Cu2+ rejection was found to be a combination of electrostatic repulsion and adsorption, with the relative proportions depending on the nature of the PEI modified PA membrane. In addition, the Cu2+ rejection and membrane flux were found to be sustainable over repeated filtration cycles, and the rejection was not adversely affected by the presence of humic acid in solution (5 mg/L).

Rheology of Triamine Functionalized Silica Reinforced Polymeric Gels Developed for Conformance Control Applications

Recently, crosslinked polymers such as polyacrylamide (PAM)/ polyethyleneimine (PEI) have been used in conformance control applications to replace conventional lost circulation materials (LCMs). The objective of this work is to introduce functionalized silica to reinforce PAM and enhance gel performance at high temperature high pressure (HTHP) conditions. A system was developed using PAM / Triamine silica (TAS) combined with nanosilica (NS) to replace the conventional PEI as a crosslinker. Polymer systems consisted of 9 wt. % PAM and Polyacrylamide tert-butyl (PAtBA) with various concentrations of PEI, TAS and NS (50 nm) were used to produce mature gels at 130oC. The results have shown that TAS has formed a gel with code “E” on Sydansk coding system. Adding low concentration (1 – 2 wt. %) of 50 nm silica has eliminated the settling of micro-sized TAS and produced a reinforced gelant system with code “I”. The crosslinking was accomplished via amine group similar to PEI mechanism with the advantage of stren...

Dispersion behavior of HfC‐based nanopowders in ethanol

AbstractThe dispersion behavior of two different types of ultrafine HfC‐based powders in ethanol was investigated using polyethyleneimine (PEI) as a dispersant. The first type was synthesized by carbothermal reduction using a modified spark plasma sintering technique (d50: 125 nm). For the 10 wt% HfC suspensions, the highest zeta potential value (67.7 mV), the least sediment after sedimentation test for one day, and finest particle sizes were obtained when the concentration of PEI was 2.0 wt%. The concentrated HfC slurries with a solid loading of 40 vol% were achieved using 1.0 wt% PEI. The second type was mixing the HfC powder with HfSi2‐C additives using a high‐energy ball milling. The concentrated HfC slurry containing 20 wt% of HfSi2‐C sintering additives was prepared up to 50 vol% solid loading using 0.50 wt% PEI. This is the first report for producing highly concentrated HfC‐based nano slurries, which were highly suitable for the wet process of ultrahigh‐temperature ceramic matrix composites (UTHCMCs).

Polyethyleneimine-functionalized phenolphthalein-based cardo poly(ether ether ketone) membrane for CO2 separation

Phenolphthalein-based cardo poly(ether ether ketone) (PEEKWC)/polyethyleneimine (PEI) crosslinking membranes were prepared by solution casting followed by solution reaction at room temperature. The effects of reaction time and PEI content on the membrane structure and gas separation performances were investigated. Light transmittance measure and AFM evidenced the relationship between the microphase separation in PEEKWC-PEI membranes and reaction time. The CO2 permeability increased with the PEI content, while the N2 and CH4 permeability remained nearly constant. This result indicated that only CO2 was transported by the solution–diffusion mechanism and also that PEI exhibited a positive contribution as a fixed carrier for CO2 facilitated transport. Meanwhile the PEEKWC-PEI crosslinking membranes showed higher selectivities than the pure PEEKWC membrane. The highest CO2/N2 and CO2/CH4 selectivities were about 131 and 122 increasing from 33 and 30, respectively. The crosslinking structure of membranes improved the CO2 permeability stability.

Aqueous Phase Synthesis of Cu2-x S Nanostructures and Their Photothermal Generation Study.

Size- and shape-dependent features of plasmonic nanocrystals govern the development of their applications. In the past decades, gold nanostructures, such as gold nanorods and nanoshells, have been well studied and applied for sensing, bioimaging, and photothermal generation. However, knowledge of copper chalcogenide, a new generation of plasmonic nanomaterials, is limited, especially about their preparation and size- and shape-dependent photothermal properties. In this work, controllable size and shape Cu2–xS nanocrystals (NCs) are synthesized by a facile aqueous route. Using low-molecular-weight polyethylenimine (PEI) as the reducing and capping agents, the size and shape of Cu2–xS NCs can be controlled with lengths from 6.5 to 46.5 nm and the aspect ratio from 2.2 to 7.5 by adjusting the concentration of PEI. The plasmonic peak of Cu2–xS experiences a redshift (from 1145 to 1369 nm) when the length increases from 6.5 to 44.5 nm. Under the irradiation of 1064 nm laser with 1.33 W/cm2, an excellent photothermal conversion rate (from 34.9 to 49.0%) is obtained. The characterization of Cu2–xS NCs is conducted with a UV–vis spectrometer, transmission electron microscopy, powder X-ray diffraction measurements, and 1064 nm laser.

High iodine adsorption by polyethyleneimine impregnated nanosilica sorbents

Abstract In this study, several nanoporous silica of SBA-15 and Aerosil types were impregnated with branched polyethyleneimine (PEI) with the aim to evaluate their iodine adsorption performance. First, the influence of the PEI content of the sorbents on their textural, structural, thermal and chemical characteristics, was studied by different techniques including N2 porosimetry at 77 K, SAXS, FTIR/ATR, elemental analysis, and TGA. Then, I2 adsorption capacities were determined in liquid phase (cyclohexane) at 20 °C, or during static or dynamic gas-phase tests, performed at 60 and 100 °C, respectively. An exceptionally high adsorption capacity superior to 2 g/g in the 20–100 °C range was determined for the SBA-15 sorbent with 38 wt% PEI (corresponding to N content of 12.3 wt%). The adsorption capacities of the sorbents increase almost linearly with the N content below this threshold, whereas the presence of excess PEI in the pores or at the pore mouth reduces the accessibility of I2 molecules to the most buried nitrogen sites. The interaction mechanisms of iodine with amine-containing molecules were investigated both from experiments carried out in solution and from the after-test characterization of the spent solids by DR-UV-Vis, FTIR/ATR, Raman spectroscopies and iodine desorption monitored by TGA. This allowed shedding light on the nature of charge-transfer complexes and the formation of ionic and neutral iodine ad-species during iodine adsorption.

Preparation, characterization and antibacterial properties of cellulose membrane containing N-halamine

Polyethylenimine (PEI), a type of water-soluble chain polymer containing a great number of primary, secondary and tertiary amine groups in the molecule, was used as an N-halamine precursor. It was grafted onto dialdehyde cellulose membrane (DCM) followed by chlorination to prepare a novel N-halamine antibacterial cellulose membrane (Cl–PEI–DCM). The appropriate conditions affecting the aldehyde content of DCM and the active chlorine (Cl+) content of Cl–PEI–DCM were systematically studied at oxidation, grafting and chlorination stages, respectively. The structure and properties of the samples were investigated by SEM, ATR–FTIR, XRD, XPS, light transmittance measurements and tensile tests. The stability and rechargeability of the Cl–PEI–DCM were evaluated, and its antibacterial activity was tested against S. aureus and E. coli. Results showed that the Cl+ content of the chlorinated samples was strongly dependent on the aldehyde content of DCM and PEI concentration. Under the optimum testing condition, the Cl+ content of the Cl–PEI–DCM reached 1.30 wt%. The hydroxyl groups on the cellulose membrane were changed to aldehyde groups and the successful introduction of PEI and N–Cl bond were confirmed. The 1.30 wt% Cl–PEI–DCM exhibited high antibacterial activity against both S. aureus and E. coli, which can completely inactivate two bacterial pathogens within 5 min even after 15 days of storage. Moreover, the Cl–PEI–DCM membrane displayed good stability, rechargeability, transparency and high mechanical strength. These results demonstrated that the Cl–PEI–DCM can be considered as a visualized wound dressing material or antibacterial shoe insole.

Level-expansion: A statistical sequential design methodology with application to nanomaterial synthesis

Nanotechnology is an era-defining breakthrough across science and engineering. For example, one-dimensional nanostructures such as nanowires, nanotubes, and nanobelts are widely regarded as critical building blocks for creating the next generation of devices in electronics, optics, energy, and biomedicine. Motivated by a practical problem of sequential synthesis of nanowires, we propose a new statistical design augmentation method, called level-expansion. For a fractional factorial design at two levels, this method creates a follow-up design by expanding some of the factors in the initial design to four elaborately chosen levels and reversing the signs of the remaining factors. The augmented design produced as such strikes a fine balance between dealiasing and entertaining nonlinear effects. Some statistical properties of the proposed method are derived. The effectiveness of the proposed method is successfully illustrated with a case study for growing a type of zinc-oxide nanowire. The use of level-expansion in the case study unveils some previously unknown nonlinear relationships between the concentration of polyethyleneimine and the length of nanowires. This finding is important for nanoscientists to invent new zinc-oxide nanowires with better macroscopic transport properties. Besides nanotechnology, the proposed method applies broadly to problems in many other scientific fields with similar traits where a follow-up design is needed for the dual purposes of investigating nonlinear effects and dealising.

Polyethylenimine-mediated gold nanoparticle arrays with tunable electric field enhancement for plasmonic applications

Localized surface plasmon resonance (LSPR) technologies are used in some of the most effective optical biosensors and can be used for the detection of biomolecules at ultralow concentrations. The construction of ordered nanoparticle arrays is important for LSPR and biosensing applications. The main challenge in the development of LSPR-based sensors is optical instability, which mainly originates from the detachment or aggregation of the gold nanoparticles (AuNPs) on the plasmonic surfaces. In this study, highly monodisperse and stable AuNPs with a particle size from 20.39 ± 1.2 to 106.17 ± 1.6 nm were synthesized by using the Turkevich and seed-and-growth methods. Here, we aimed to control the construction of plasmonic AuNPs by using the electrostatic assembly of oppositely charged polycationic polymer. For this purpose, we used positively charged polyethylenimine (PEI) to immobilize AuNPs on the disposable polystyrene surface and designed a model for plasmonic sensing. Our results confirmed that the 1-mg/mL PEI concentration efficiently prevented the aggregation or detachment of immobilized AuNPs. LSPR peak wavelengths were adjustable in the range from 530 ± 2.0 to 548 ± 1.5 nm. In addition, we theoretically showed that electric field enhancement within the gaps of nanoparticle arrays could enhance the sensitivity of the plasmonic surfaces. Such nanoplasmonic surfaces could be important in fabricating facile sensing devices and could be easily integrated into bioelectronics and microfluidic devices.

Nanodiamond coating by polyethylenimine for optical limitation

Polyethylenimine (PEI) is used to elaborate detonation nanodiamonds coated with a polymer material. Evolution of the nanodiamonds surface charge depending on the PEI concentration is revealed by a zeta potential study. While the surface charge of the nanodiamond is negative due to its oxygenated functional groups, the cationic polymer allows reversing it to a positive one. Spectroscopy characterizations are used to investigate the PEI interaction with the nanodiamonds and to estimate the very small thickness of the PEI layer on the nanodiamonds surface. The oxygenated functional groups of the nanoparticles interact electrostatically with the PEI amine groups. The good performances of the non-linear optical properties of this material are demonstrated at a wavelength of 1064 nm.

A novel and effective Zn/PEI-MCM catalyst for the acetylene hydration to acetaldehyde

MCM-41 material was modified by polyethyleneimine (PEI) using ultrasonic assisted impregnation method with different PEI loading (P-MCM-x, x = 0–15 wt%). The synthesised P-MCM-x materials and corresponding Zn/P-MCM-x catalysts were characterised by FTIR, XRD, TEM, BET, XPS, TG and H2-TPR, as well as their catalytic performance in the hydration of acetylene was investigated. The results showed that the modified materials retained the mesoporous structure with good thermostability, and the corresponding Zn/P-MCM-x displayed the higher catalytic performance than that of Zn/MCM-41 catalyst, especially for the Zn/P-MCM-12 catalyst with about 88% C2H2 conversion and 85% selectivity, and the optimal content of PEI is 12 wt%. More importantly, the introduction of PEI enhanced metal-support interaction to make the better metal dispersion and more active sites, and the charge transfer from N atom to Zn species. These all would be responsible for the high activity of the modified Zn catalysts in the acetylene hydration.

A facile preparation of positively charged composite nanofiltration membrane with high selectivity and permeability

An excellent positively charged nanofiltration (NF) membrane is of great significance for water softening. In this work, a novel positively charged composite PEI/TMA NF membrane was prepared by gradient cross-linking polyethyleneimine (PEI) with trimesic acid (TMA) on polyethersulfone ultrafiltration (PESU) membrane. The effects of concentration of PEI and TMA, the cross-linking reaction temperature and reaction time on membrane structure and performance were investigated in detail. The effects of PEI and TMA, reaction temperature and time on the membrane structure, composition and performance were investigated. The optimized preparation conditions of PEI/TMA NF membrane were fixed at 0.6% (m/v) PEI, 0.1% (m/v) TMA, 0.15% (m/v) SDS at 90 °C for 10 min. The as-prepared membrane exhibited a pure water flux of 19.1 L m−2 h−1 bar−1 and a rejection of MgCl2 93.0%, NaCl 38.2%, MgSO4 20.4%, and Na2SO4 8.8%. The functional layer is ultra-thin. Its high selectivity mainly results from Donnan effect. The long-term testing of our PEI/TMA NF membrane show a high stability. Compared with other positively charged membranes, the PEI/TMA NF membrane had unique advantages in the production process and a comprehensive performance.

Stability of polyethylenimine solution‐in‐liquid paraffin emulsion for preparing polyamine microspheres with potential adsorption for ionic dyes

AbstractA microsphere synthesized by emulsion crosslinking of polyethylenimine (PEI) was applied in the removal of ionic dyes from water. Firstly, the stability of the PEI solution‐in‐liquid paraffin emulsion was improved by using the mixture of Span‐80/Tween‐80 as the emulsifier. The optimization by 25‐1 fractional factorial design demonstrated the most stable emulsion was prepared at 0.07 g/mL of the emulsifier dosage, 6:4 (v:v) of the oil/water ratio, 20 % (wt %) of the PEI concentration, 6:1 (w:w) of the Span‐80/Tween‐80 ratio with a homogenization speed of 6000 r/min for 3 min at 25 oC. Then, the polyamine microsphere (PA‐M) was obtained by crosslinking the PEI emulsion with glutaraldehyde. The PA‐M microsphere can adsorb xylenol orange (XO) from aqueous solution with a capacity of 1169.2±12.5 mg/g. The amount of XO adsorption remained constant in the pH range of 2.0‐11.0. Adsorption kinetics analysis demonstrated that Pseudo first‐order model fit the experimental data better, indicating the overall adsorption process was controlled by ‘surface reaction’. The XO adsorption on the microsphere was due to an electrostatic interaction according to the results of ΔG evaluation. The value of separation factor suggested the XO adsorption was favorable. The used PA‐M microsphere can be regenerated and reused in adsorption/desorption operation at least 20 times.