PEI Content Research Articles

Effect of incorporation of multi-walled carbon nanotubes on the CO2/CH4 separation performance of sulfonated poly (ether ether ketone) / polyetherimide composite membranes using design of experiments and molecular dynamics simulation methods

Blend membranes were prepared based on sulfonated poly (ether ether ketone) (SPEEK) and poly (etherimide) (PEI) using different amounts of multi-wall carbon nanotubes (MWCNTs) (up to 2 wt%). PEEK has been sulfonated directly to reach 70 % degree of sulfonation. The manufactured membranes were examined by X-ray diffraction (XRD), scanning field emission electron microscopy (FESEM), Fourier transformed infrared spectroscopy (FTIR). The effect of the composition of SPEEK / PEI on membrane selectivity was investigated under different feed pressures (2 to 8 bar) and temperatures (25 to 55 °C). The values of selectivity and gas permeability were varied between the value of the individual polymers, fluctuating systematically with SPEEK / PEI content variation in the blends. TGA and tensile tests result obtained for prepared membranes shown that the hybrid membrane had good thermal and mechanical properties. The addition of MWCNTs to the blend led to simultaneously improve the selectivity and permeability of the pair gases of CO2 and CH4. The permeability of CO2, as well as CH4/CO2 selectivity for the membrane with the same weight of SPEEK and PEI, and 1 wt% of MWCNTs (coded SP55M1) experienced an increase of about 22 % compared with the neat membrane. Molecular dynamics simulations (MDS) were performed by employing the COMPASS force field to estimate the diffusivity of CH4 and CO2 gases through selected membranes. At last, with compared to the obtained experimetal data, the optimized nanocomposite membrane, integrated with MWCNTs was efficient, which makes it promising platform to separate mixed gase flows of CO2 and CH4 and other related environmental processes.

High-flux, antifouling and highly hydrophilic tight ultrafiltration membranes based on crosslinked PEEKWC/PEI containing positively charged water channel for dyes removal

For the removal of textile dyes, an effective alternative to fabricate tight ultrafiltration membrane was adopted. A series of tight ultrafiltration membranes based on PEEKWC/PEI covalent crosslinking structure were prepared by phase inversion method and showed high-flux and good antifouling performance attributed to the enhancement of hydrophilicity by PEI. The top-surface of the UF membranes was with a water contact angle in range of 24.33° and 40.10° indicating the excellent hydrophilicity. These membranes containing PEI-based positively charged water channel showed high permeability for pure water and salt solutions. As the content of PEI in membrane reaching 20 wt%, the pure water permeability and pure water flux at 3 bar could reach 308 L·m−2·h−1·bar−1 and 925 L·m−2·h−1, respectively. The pure water flux could even reach 1526 L·m−2·h−1 at 5 bar. At the operation pressure of 3 bar, all the UF membranes showed good single-component BBR rejection between 94.87 % and 97.73 %. The rejection of membranes for BBR in dye/salt mixtures was substantially higher than 94.0 % even at a high salt concentration of 60 g/L. The UF membranes with high-flux of pure water and dye solution were discussed, which could be a promising alternative for sustainable textile wastewater treatment and natural water recovery.

Gas permeation and microstructure of reduced graphene oxide/polyethyleneimine multilayer films created via recast and layer-by-layer deposition processes.

Nowadays, graphene/polymer composite films with multilayer structure have attracted significant attention for gas barrier application. In this study, a series of reduced graphene oxide/polyethyleneimine (RGO/PEI) composite films were created via recast and layer-by-layer deposition processes. By using the recast process, the myriad PEI molecules in the precursor solution (the PEI : GO feeding ratio is 0.02 : 0.1, 0.05 : 0.1, 0.1 : 0.1, 0.3 : 0.1 and 0.5 : 0.1) ensure more effective reduction and surface modification of the graphene oxide (GO) sheets, while the undesirable free PEI molecules are eventually removed via a filtration process. Then, the RGO/PEI composite films were synthesized on PET substrate using a layer-by-layer assembly. The resulting films show a homogeneous and compact brick-wall structure with excellent gas barrier properties. Barriers against water vapor, nitrogen/oxygen, and carbon dioxide require different content of PEI in the composite film for optimal performance; the ideal values are 19.7, 23.8, and 24.1 wt%, respectively. These values are much lower compared with previously reported studies. Further, the permeability, free volumes, component ratio, morphology, and density of the RGO/PEI composite films have been carefully investigated and discussed. The results revealed that the mechanism behind the excellent gas barrier property of the RGO/PEI composite films is a synergistic effect created by the combination of the brick-wall structure, the small free volume holes, the suitable PEI content (ranging from 19.7 wt% to 24.1 wt%), the high density, and the hydrophobicity.

Enhanced fracture resistance of thermoset/thermoplastic interfaces through crack trapping in a morphology gradient

The hybrid assembling of thermoplastics with thermosets through controlled interdiffusion is an attractive approach towards integrated structural composite bonding. The fracture toughness of the interphase between the high Tg thermoplastic polyetherimide and the RTM6 epoxy is found to be four times higher than the corresponding RTM6 value under specific curing cycle. The origin of this remarkable cracking resistance is elucidated by analyzing the crack path in relationship with the morphology and local elastoplastic and fracture properties of the interphase. The crack is trapped inside a morphological gradient involving a relatively low PEI concentration. Uniaxial compression and nanoindentation tests on homogenous blends exhibit an unexpected softening in this PEI content window. This efficient crack trapping mechanism originates thus from a synergistic coupling between a lower local strength and higher local fracture toughness. This finding opens to many new options for interface toughening beyond the system addressed in this research.

Construction and Mechanism Analysis of a Self-Assembled Conductive Network in DGEBA/PEI/HRGO Nanocomposites by Controlling Filler Selective Localization.

Herein, a feasible and effective approach is developed to build an electrically conductive and double percolation network-like structure via the incorporation of highly reduced graphene oxide (HRGO) into a polymer blend of diglycidyl ether of bisphenol A/polyetherimide (DGEBA/PEI). With the assistance of the curing reaction-induced phase separation (CRIPS) technique, an interconnected network of HRGO is formed in the phase-separated structure of the DGEBA/PEI polymer blend due to selective localization behavior. In this study, HRGO was prepared from a unique chemical reduction technique. The DGEBA/PEI/HRGO nanocomposite was analyzed in terms of phase structure by content of PEI and low weight fractions of HRGO (0.5 wt.%). The HRGO delivered a high electrical conductivity in DGEBA/PEI polyblends, wherein the value increased from 5.03 × 10−16 S/m to 5.88 S/m at a low content of HRGO (0.5 wt.%). Furthermore, the HRGO accelerated the curing reaction process of CRIPS due to its amino group. Finally, dynamic mechanical analyses (DMA) were performed to understand the CRIPS phenomenon and selective localization of HRGO reinforcement. The storage modulus increased monotonically from 1536 MPa to 1660 MPa for the 25 phr (parts per hundred in the DGEBA) PEI polyblend and reached 1915 MPa with 0.5 wt.% HRGO reinforcement. These simultaneous improvements in electrical conductivity and dynamic mechanical properties clearly demonstrate the potential of this conductive polyblend for various engineering applications.

DNA delivery systems based on copolymers of poly (2‐methyl‐2‐oxazoline) and polyethyleneimine: Effect of polyoxazoline moieties on the endo‐lysosomal escape

AbstractPoly(2‐methyl‐2‐oxazoline)‐polyethylenimine (PMeOx‐co‐PEI) copolymers differing by degree of polymerization (DP = 50 and 200) and PEI content (from 37 to 99 mol%) were synthesized by living cationic ring‐opening polymerization of 2‐methyl‐2‐oxazoline, followed by partial hydrolysis. Upon mixing with DNA in a wide range of N/P ratios, they formed well‐defined polyplex particles of small size (typically below 100 nm) and narrow size distribution. The polyplexes demonstrated good colloidal stability and very low in vitro cytotoxicity. The copolymers exhibited buffering capacity of over 50% relative to that of the reference PEI implying effective endo‐lysosomal escape of the polyplexes. Increased cellular internalization of both PCR fragments and plasmid DNA, attributable to the strongly positive ζ potential and small size of the polyplexes, was observed. In spite of these favorable prerequisites, the transfection efficiency was low (below 20% relative to the control PEI) and was attributed to retarded swelling of the polyplex particles, endo‐lysosomal rupture, and DNA release.

Amphiphilic Polymethyloxazoline-Polyethyleneimine Copolymers: Interaction with Lipid Bilayer and Antibacterial Properties.

Polycations, mimicking activity of antibacterial peptides, belong to an important class of molecules investigated as a support or as an alternative to antibiotics. In this work, studies of modified linear amphiphilic statistical polymethyloxazoline (PMOX) and polyethyleneimine copolymers (PMOX_PEI) series are presented. Variation of PEI content in the structure results in controllable changes of polymeric aggregates zeta potential. The structure with the highest positive charge shows the best antimicrobial activity, well visible in tests against model Gram-positive and Gram-negative bacteria, fungi, and mycobacterium strains. The polymer toxicity is evaluated with MTT and hemolysis assay as a reference. Quartz crystal microbalance (QCM-D) is used to investigate interaction between polycations and a model lipid membrane. Polymer activity correlates well with molecular structure, showing that amphiphilic component is altering polymer behavior in contact with the lipid bilayer.

Fabrication of electrospun ibuprofen-loaded poly(vinyl alcohol)/hyper-branched poly(ethylenimine) fibers and their release behaviors

A novel transdermal drug delivery system for the release of ibuprofen (IBU) was fabricated via poly(vinyl alcohol)/hyper-branched poly(ethylene imine) (PVA/PEI) nanofibrous membranes. Hence, PVA/PEI solutions were electrospun at different PVA/PEI mass ratios of 100/0, 85/15, 75/25, and 65/35. SEM observations illustrated that the diameters of collected fibers to be 125–161 nm. Fourier-transform infrared and differential scanning calorimetric characterizations were used to examine microstructural changes of fibers. In vitro drug release revealed that the amount of drug loaded in PVA/PEI fibers increased by enhancing PEI content due to abundant amine terminated groups as well as hollow interior between branches. The maximum concentration of released drug equal to 130.69 mg/L was achieved for PVA/PEI (75/25) fibers, which is about 2.5 times higher than drug-loaded PVA fibers. An increase of 34% in drug release characteristic of fibrous structure comparing with as-cast film was also obtained at 24 h of immersion time. The decreased release rate of IBU was shown for drug-loaded PVA and PVA/PEI fibers heat-treated at 140 °C and 120 °C, respectively. By assessing drug release mechanism through so-called Peppas kinetic model, it was found that heat treatment changed release mechanism from swelling-controlled to diffusion-controlled for drug-loaded PVA/PEI fibers. Overall, IBU-loaded PVA/PEI fibrous membrane presents a substantial potential for drug delivery systems with anti-inflammation and analgesic-eluting applications.

Facile synthesis of bacterial cellulose and polyethyleneimine based hybrid hydrogels for antibacterial applications

Bacterial cellulose (BC) has numerous unique properties; however, the lack of antibacterial properties has restricted its biomedical applications. To resolve this problem, we have developed BC/polyethyleneimine (PEI)-based antibacterial hydrogels by a facile two-step-one-pot method using epichlorohydrin (ECH) as a coupling agent. ECH was added to BC solution and homogenized, followed by cross-linking with different content of PEI. The prepared hydrogels showed thermal stability, moldability, and PEI-content dependent mechanical properties. Furthermore, the antibacterial properties of the prepared hydrogels were investigated against S. aureus and E. coli by agar well diffusion method and colony forming unit method. All hydrogels containing PEI showed antibacterial properties dependent on PEI content. The hydrogels containing PEI ≥ 12.88 mg/mL showed more than 99% antibacterial activity against both strains. We believe that the prepared hydrogels can find potential applications in biomedical fields.

Effect of the amount of polyetherimide on the properties of a composite membrane using a design of experiments

The main objective of this study is to find the link between a maximum magnitude of interest, it is the flow noted Y and the factors: it is the percentage in % wt of monomers noted xi. Then, optimizing a study at a lower cost and producing maximum efficiency. This study reveals that the synthesis of the new composite membrane, from a polyetherimide PEI and a Polysulfone PSU physical copolymer consisting of two monomers, by choosing a factorial design (x 1 , x 2 , x 3 , x 4 ). This was done thanks to the help of the most widespread software in the optimization and organization of preventive tests of scientific research (experimental design of Nemrodw). The results obtained show that the flow of the membrane increases as a function of the increase in the weight content of PEI in the organic mixture.

Cold Sintering Na2Mo2O7 Ceramic with Poly(ether imide) (PEI) Polymer to Realize High-Performance Composites and Integrated Multilayer Circuits

The cold-sintering process is utilized to fabricate ceramic–polymer (Na2Mo2O7-poly(ether imide), PEI) composites and integrated multilayer circuits. The Na2Mo2O7-PEI bulk composites cold-sintered at 120 °C show high densities (>90% theoretical). The permittivity at microwave frequencies decreases with increasing PEI content, following the classical logarithmic mixing law, and Qf values show no deterioration with the addition of PEI. Furthermore, the characteristic dielectric breakdown strength of the ceramic–polymer composite obtained from a Weibull plot increases dramatically from 55.1 to 107.5 MV/m with 10–20 vol % PEI additions. In the case of high PEI content where there is more segregation of the polymer within the ceramic matrix, there is a gradual decrease in the dielectric breakdown strength. Na2Mo2O7-PEI-Ag bulk ring resonators can be obtained by post screen printing, and the mixing laws are used to calculate the permittivity of the ring resonators. As a prototype of integrated multilayer circuit...

Spherical Nucleic Acid Architecture Can Improve the Efficacy of Polycation-Mediated siRNA Delivery

Clinical translation of small interfering RNA (siRNA) nanocarriers is hindered by limited knowledge regarding the parameters that regulate interactions between nanocarriers and biological systems. To address this, we investigated the influence of polycation-based nanocarrier architecture on intracellular siRNA delivery. We compared the cellular interactions of two polycation-based siRNA carriers that have similar size and surface charge but different siRNA orientation: (1) polyethylenimine-coated spherical nucleic acids (PEI-SNAs), in which polyethylenimine is wrapped around a spherical nucleic acid core containing radially oriented siRNA and (2) randomly assembled polyethylenimine-siRNA polyplexes that lack controlled architecture. We found that PEI-SNAs undergo enhanced and more rapid cellular uptake than polyplexes, suggesting a prominent role for architecture in cellular uptake. Confocal microscopy studies demonstrated that while PEI-SNAs and polyplexes exhibit similar intracellular stability, PEI-SNAs undergo decreased accumulation within lysosomes, identifying another advantage conferred by their architecture. Indeed, these advantageous cellular interactions enhanced the gene silencing potency of PEI-SNAs by 10-fold relative to polyplexes. Finally, cytocompatibility studies showed that PEI-SNAs exhibit decreased toxicity per PEI content relative to polyplexes, allowing the use of more polycation. Our studies provide critical insight into design considerations for engineering siRNA carriers and warrant future investigation of how nanocarrier architecture influences cellular-, organ-, and organism-level interactions.

NEW ENVIRONMENTALLY FRIENDLY DUST SUPPRESSANT BASED ON LIGNOCELLULOSIC BIOMASS FROM WOOD PROCESSING WASTEWATER

In this work, the possibility of usage of lignocellulosic biomass derived from wood processing wastewater as an environmentally friendly dust suppressant was studied. To increase the efficiency of the recovery of lignocellulosic biomass, a new developed composite coagulant, representing a polymer-colloid complex of polyethyleneimine with polyvalent metal ions, was applied. The effectiveness of the composite coagulant was examined using a model solution simulating the wastewater of hydrothermal treatment of birch wood. The optimum content of PEI in the composite coagulant was found to be 25-35%. At the optimal composite coagulant dosage and pH value, the yield of the total wood biomass achieved 97%, but the extraction of lignin and lignin-like substances was more than 65%. Due to the polymeric and polyfunctional nature, the recovered wood biomass had glue properties. Taking into account the fact that the dust at the surface of unpaved roads poses considerable environmental problems, the biomass was tested as a structuring agent for sandy and model sandy-clay soils. The obtained results have shown that the separated lignocellulosic biomass was capable of forming large sandy aggregates that were able to decrease the dusty soil blowing off from the unpaved road surface.

Preparation and properties of positively charged mesoglobules based on poly(2-isopropyl-2-oxazoline) and evaluation of their potential as carriers of polynucleotides

A series of random copolymers of 2-isopropyl-2-oxazoline and ethylenimine (PiPOX-ran-PEI) with PEI contents 5–84% were prepared by partial acidic hydrolysis of poly(2-isopropyl-2-oxazoline) (PiPOX). Dynamic and electrophoretic light scattering were utilized to investigate aqueous solution properties of the copolymers. Above the phase transition temperature of PiPOX, well-defined nanoparticles (mesoglobules) typically ranging in size 200–500 nm, depending on the heating protocol, and surface potential reaching +35 mV, were formed. The mesoglobules consisted of a core dominated by PiPOX and a thin positively charged shell from PEI moieties which mediated formation of polyplexes with DNA. Upon complexation with DNA, performed at 65 °C and at varying N/P (amine-to-phosphate groups) ratios, well-defined polyplex particles with dimensions ranging between 110 and 250 nm and typically negative ζ potential were formed. Cooling down to the physiologically relevant temperature of 37 °C resulted in a slight-to-moderate increase of the size due to swelling of the polyplex particles and reduction of the negative ζ potential. The copolymers with PEI contents ≥15% can be considered perspective for delivery of polynucleotides.

Poly(ethylenimine)-Functionalized Monolithic Alumina Honeycomb Adsorbents for CO2 Capture from Air.

The development of practical and effective gas-solid contactors is an important area in the development of CO2 capture technologies. Target CO2 capture applications, such as postcombustion carbon capture and sequestration (CCS) from power plant flue gases or CO2 extraction directly from ambient air (DAC), require high flow rates of gas to be processed at low cost. Extruded monolithic honeycomb structures, such as those employed in the catalytic converters of automobiles, have excellent potential as structured contactors for CO2 adsorption applications because of the low pressure drop imposed on fluid moving through the straight channels of such structures. Here, we report the impregnation of poly(ethylenimine) (PEI), an effective aminopolymer reported commonly for CO2 separation, into extruded monolithic alumina to form structured CO2 sorbents. These structured sorbents are first prepared on a small scale, characterized thoroughly, and compared with powder sorbents with a similar composition. Despite consistent differences observed in the filling of mesopores with PEI between the monolithic and powder sorbents, their performance in CO2 adsorption is similar across a range of PEI contents. A larger monolithic cylinder (1 inch diameter, 4 inch length) is evaluated under conditions closer to those that might be used in large-scale applications and shows a similar performance to the smaller monoliths and powders tested initially. This larger structure is evaluated over five cycles of CO2 adsorption and steam desorption and demonstrates a volumetric capacity of 350 molCO2 m-3monolith and an equilibration time of 350 min under a 0.4 m s(-1) linear flow velocity through the monolith channels using 400 ppm CO2 in N2 as the adsorption gas at 30 °C. This volumetric capacity surpasses that of a similar technology considered previously, which suggested that CO2 could be removed from air at an operating cost as low as $100 per ton.

Temporal evolution of structure in uniaxially stretched PET/PEI blends during constrained annealing: A real time birefringence study

Abstract Structure evolution that took place during the constrained annealing of uniaxially constrained width oriented Poly (ethylene terephthalate) and Poly (ether imide) blend films was studied using real time spectral birefringence measurement technique and off line differential scanning calorimetry, wide and small angle X-ray scattering and mechanical testing. At lower deformations, heat setting generally lead to complete elimination of birefringence due to relaxation in blends containing as little as 10% PEI. At high deformation levels, annealing leads to initial relaxation nearly to optical isotropy followed by reversal and increase in birefringence associated with development of crystallization. The ultimate birefringence decreases with increasing PEI content as it disrupts crystallization. Latter behavior indicates that despite achieving near optical isotropy during initial relaxation phase, these films still contain oriented nuclei that facilitate the oriented crystallization of the PET phase at longer annealing times as evidenced by the off line WAXS and SAXS experiments.

Reactive compatibilization of polyetherimide with polyamide 6,6: Part 2. Effect of epoxy-functionalized polyamide

The addition of end-functionalized polyamide 66 (fPA) greatly improved the compatibility of fPA/polyether imide (PEI) blends. The compatibility and interaction of the components in the blends were characterized by Fourier transform-infrared spectra, Molau tests, melt flow index, dynamic mechanical analyses, heat deflection test, Izod impact test, and scanning electron microscopic observations. The results show that the epoxy end group in fPA can react with the amino or the carboxylic end groups in PEI. In this way, the in situ-formed fPA-b-PEI copolymer anchors at the interface of fPA/PEI blends. The morphological study of the fracture sections before and after impact test reveals that the PEI particles were dispersed uniformly in the fPA matrix and the interfacial adhesion between fPA and PEI was increased significantly compared to the unmodified PA66/PEI blend. The thermal mechanical properties of the blends thus were enhanced with increasing degree of functionalization of fPA. Next the fPA content, with the highest degree of functionalization at 3.4 %, was varied from 0 to 60 wt%; whereas, the content of PEI was held at 40 wt% in the PA66/fPA/PEI blends, and in all cases the PEI formed the dispersed phase. From various characterization results, the peak property improvement was reached at 20 wt% fPA. Besides, most high-temperature properties of the ternary blend were raised over the neat PA66.

Synthesis and Characterization of Poly (Methyl Methacrylate)/Polyethylenimine Grafting Core-Shell Nanoparticles for CO<sub>2</sub> Adsorption Using Soap-Free Emulsion Copolymerization

Unlike previous emulsion polymerization, we used grafting reactions in soap-free emulsion systems. In this study, we synthesized grafted PMMA/PEI core-shell nanoparticles by varying the MMA/PEI content and molecular weight of PEI (Mn = 600, 8000, and 10,000). The size and morphology of the core-shell nanoparticles were characterized by a particle size analyzer and scanning electron microscopy. The nanoparticles were 178 - 408 nm in diameter and swelled in water or methanol by 30 - 75 nm. The size of the nanoparticles increased with MMA contents, whereas the size distribution progressively became homogeneous with increasing molecular weight of PEI. Lastly, we measured CO2 adsorption capacity of the grafted PMMA/PEI core-shell nanoparticles, and we found the capacity to be limited at a level of 0.69 mg, which occurred for nanoparticles prepared from emulsions at a pH value of 11.

Multi-functionalized graphene oxide complex as a plasmid delivery system for targeting hepatocellular carcinoma therapy

A novel and efficient graphene-based gene delivery vector was prepared, the effect of changing the PEI content on the size, stability and transfection efficiency were investigated.

Role of Additives in Composite PEI/Oxide CO₂ Adsorbents: Enhancement in the Amine Efficiency of Supported PEI by PEG in CO₂ Capture from Simulated Ambient Air.

Supported amines are promising candidate adsorbents for the removal of CO2 from flue gases and directly from ambient air. The incorporation of additives into polymeric amines such as poly(ethylenimine) (PEI) supported on mesoporous oxides is an effective strategy to improve the performance of the materials. Here, several practical aspects of this strategy are addressed with regards to direct air capture. The influence of three additives (CTAB, PEG200, PEG1000) was systematically explored under dry simulated air capture conditions (400 ppm of CO2, 30 °C). With SBA-15 as a model support for poly(ethylenimine) (PEI), the nature of the additive induced heterogeneities in the deposition of organic on the interior and exterior of the particles, an important consideration for future scale up to practical systems. The PEG200 additive increased the observed thermodynamic performance (∼60% increase in amine efficiency) of the adsorbents regardless of the PEI content, while the other molecules had less positive effects. A threshold PEG200/PEI value was identified at which the diffusional limitations of CO2 within the materials were nearly eliminated. The threshold PEG/PEI ratio may have physical origin in the interactions between PEI and PEG, as the optimal ratio corresponded to nearly equimolar OH/reactive (1°, 2°) amine ratios. The strategy is shown to be robust to the characteristics of the host support, as PEG200 improved the amine efficiency of PEI when supported on two varieties of mesoporous γ-alumina with PEI.