Addition Of PEO Research Articles

Tripolyphosphate-crosslinked chitosan/poly (ethylene oxide) electrospun nanofibrous mats as a floating gastro-retentive delivery system for ranitidine hydrochloride

The present study describes the fabrication of Tripolyphosphate (TPP)-crosslinked nanofibrous mats based on chitosan for use as a floating gastro-retentive delivery system. TPP-crosslinked chitosan (CH)/poly (ethylene oxide) (PEO)- ranitidine hydrochloride (RH) electrospun nanofibers (75.27 ± 2.10 nm) were prepared by electrospinning 70% v/v acetic acid solutions, and followed by crosslinking by TPP anions. The mechanical, structural and morphological properties of the prepared nanofibers were evaluated via tensile testing, XRD, FT-IR, TGA, NMR, AFM and SEM experimental techniques. The prepared nanofibrous mats showed a pH sensitive swelling profile with maximum water absorbing at pH 1.2. Results obtained from above experimental techniques indicated that crosslinking process did not significantly altered morphological property of nanofibers but rather decreased their diameter and swelling degree, and increased their mechanical properties, thermal stability and bioadhesive strength. Viscosity measurements showed that the addition of PEO and RH to the chitosan solution, depending to its concentration lead to decrease in the viscosity of its solution. Also, floating test showed that the prepared nanofibrous mats remain floated onto surface of the dissolution medium for more than 48 h. Based on in- vitro drug release data analysis, TPP-crosslinked CH/PEO nanofibrous mats decreased initial burst release and it was exhibited a sustained release profile for the RH from the TPP-crosslinked CH/PEO-RH electrospun nanofibrous mats.

Preparation and characterization of biocomposite chitosan film containing Perilla frutescens (L.) Britt. essential oil

In the present study, biocomposite films with incorporated Perilla frutescens (L.) Britt. essential oil (PEO) were prepared using the solvent casting method. Perilla essential oil concentrations at 0.2%, 0.6%, and 1.0% (v/v) had a significant effect on the physical, chemical, and antibacterial activity of the films. Films with PEO exhibited a significant decrease (p < 0.05) in tensile strength (TS), elongation at break (%E), water vapor permeability (WVP), water solubility (WS), and swelling ratio (SR). The amounts of PEO had a significant effect on the WVP, WS, and SR but had no significant effect on the TS and%E (p < 0.05). Addition of PEO to the chitosan film significantly improved the ultraviolet–visible-light barrier of the film. The antimicrobial properties of the films were significantly enhanced by PEO. An increased roughness of the biocomposite films with added PEO was shown by scanning electron microscopy. Fourier transform infrared spectroscopy showed new interactions in the biocomposite films. X-ray diffraction measurements confirmed that the films with PEO have more dense crystalline domains in comparison with the pure chitosan film samples. Furthermore, the thermal stability of the film decreased upon PEO addition, and the weight loss of films with PEO increased with increasing amount of PEO, as suggested by thermogravimetric analyses. The biocomposite films with incorporated PEO demonstrated good activity against Escherichia coli, Staphylococcus aureus, and Bacillus subtilis, showing inhibition zone diameters (mm) of 24.563 ± 0.021 mm, 20.153 ± 0.006 mm, and 23.427 ± 0.015 mm, respectively. Overall, the biocomposite chitosan film with added PEO have potential application for food preservation as a biodegradable and ecofriendly packaging material.

Selective Acceleration of Crystal Growth of Indomethacin Polymorphs by Low-Concentration Poly(ethylene oxide).

Physical stability of pharmaceutical amorphous solid dispersions is one of the critical attributes to the successful development of the formulation. Herein, we studied the impact of low-concentration poly(ethylene oxide) (PEO) on the crystallization rates of three polymorphs of indomethacin (IMC, γ-, α-, and δ-form). We observed that the addition of 3% w/w PEO significantly increased the crystal growth rates of γ-form and α-form of IMC, but had a negligible effect on the δ-form. The reduction of the activation energy for the crystal growth of IMC polymorphs after adding the PEO follows the order γ-form > α-form > δ-form, which is consistent with the trend toward the accelerating effects of PEO on the crystal growth rates of three polymorphs. With the addition of low-concentration PEO, there is an increase of molecular mobility of IMC as evidenced by the decreased structural relaxation times and viscosities. This study suggests that the substantially different effects of PEO on the crystal growth rates of IMC polymorphs are attributable to the different adsorption of PEO on the crystal surface of those polymorphs, which in turn exerts a selective accelerating effect on IMC molecules to organize into the different crystalline phases. These findings are relevant for understanding the crystallization behavior of amorphous solid dispersions containing polymorphic drugs.

Thermal conductivity enhancement of poly(3-hydroxylbutyrate) composites by constructing segregated structure with the aid of poly(ethylene oxide)

Thermally conductive poly (3-hydroxylbutyrate) (PHB)/poly (ethylene oxide) (PEO)/boron nitride (BN) composites were fabricated by powder mixing. The thermal conductivity of PHB composite was remarkably enhanced by incorporating a small amount of PEO. SEM images revealed that segregated and co-continuous structures were formed in PHB composites. Owing to the addition of PEO, acting as a binder, BN particles were able to stack more closely and covered larger size of PHB aggregates than PHB/BN composites did. In addition, the partial miscibility between PHB and PEO could efficiently improve the interaction between BN particles and PHB matrix. Besides, during the hot pressing process, PEO could penetrate into the voids existing between BN particles and lead the phonon scattering to decrease. The hydrogen bonding existed between PEO and BN particles also played an important role to the thermal conductivity enhancement of PHB composites. These factors combined were believed to result in higher thermal conductivity of PHB/PEO/BN composites than PHB/BN composites fabricated by powder mixing.

Acceleration of Crystal Growth of Amorphous Griseofulvin by Low-Concentration Poly(ethylene oxide): Aspects of Crystallization Kinetics and Molecular Mobility.

This study aims to investigate the crystallization behavior and molecular dynamics of amorphous griseofulvin (GSF) in the presence of low-concentration poly(ethylene oxide) (PEO). We observe that the addition of 3% w/w PEO remarkably increases the crystal growth rate of GSF by two orders of magnitude in both the supercooled liquid and glassy states. The liquid dynamics of amorphous GSF in the presence and absence of PEO are characterized by dielectric spectroscopy. With an increase of the PEO content, the α-relaxation times of the systems decrease, indicating the increase of global molecular mobility. The couplings between molecular mobility and crystallization kinetics of GSF systems show strong time-dependences below Tg. The overlapping of α-relaxation times of GSF in presence and absence of PEO as a function of Tg/T suggest the "plasticization" effect of PEO additives. However, the crystallization kinetics of amorphous GSF containing low-concentration PEO do not overlap with those of pure GSF on a Tg/T scale. The remarkable accelerating effect of crystal growth of amorphous GSF by low-concentration PEO can be partially attributed to the increase of global mobility. The high segmental mobility of PEO is expected to strongly affect the crystal growth rates of GSF. These findings are relevant for understanding and predicting the physical stability of amorphous pharmaceutical solid dispersions.

Ultratough Co-Continuous PLA/PA11 by Interfacially Percolated Poly(ether-b-amide)

It will be shown that when polyether-b-amide (PEBA) is added to a PLA/PA11 blend, it tends toward the interface and results in a significant increase in the impact strength when all three phases are fully percolated. The addition of the elastomeric PEBA phase to the binary PLA/PA11 blend replaces a rigid PLA/PA11 interface with a much more deformable one. The further addition of PEO to PLA results in an ultratough material with an impact strength of ∼750 J/m, which is approximately 40 times greater than the original co-continuous PLA/PA11 blend. The tensile toughness and notched Izod impact strength are significantly influenced by the critical co-continuous composition region of the PLA/PA11 binary system and a minimum concentration to form a fully percolated PEBA layer at the co-continuous PLA/PA11 interface. The added PEO is also found to enhance the interfacial interactions and the chain mobility of PLA. The combined effects of co-continuity, strong interfacial interactions, a deformable interface, and...

Interactions between cellulose nanocrystals and anionic and neutral polymers in aqueous solutions

Physical structures of aqueous cellulose nanocrystal (CNC) suspensions in anionic polyelectrolyte carboxymethyl cellulose (CMC) and non-ionic poly(ethylene oxide) (PEO) were investigated by studying their cross polarized, polarized optical microscope (POM) images and dynamic light scattering, zeta potential, 1H spin–lattice relaxation nuclear magnetic resonance (NMR) data. The presence of anionic CMC and nonionic PEO in CNC suspensions led to two different kind of interactions. Semi-dilute CNC suspensions showed first gel-like behavior then phase separation by adding only semi-dilute un-entangled CMC polymer solutions, whereas the addition of PEO didn’t cause any significant change. POM images showed the phase transitions of CNC suspensions in the presence of CMC solutions from the isotropic state to nematic and chiral nematic phases. Dynamic light scattering, zeta potential and 1H spin–lattice relaxation NMR data presented further arguments to explain polymer-CNC interactions in CMC and PEO solutions. 1H NMR solvent relaxation technique determined the adsorption and depletion interactions between polymers and CNC. The minima in spin–spin specific relaxation rate constant showed the depletion of CNC nanoparticles in CMC. It is believed that the depletion flocculation was the case for the effects of CMC polymer chains in CNC suspensions. PEO was adsorbed on CNC surfaces and caused only weak depletion interactions due to the presence of soft particles.

The Properties of HPMC:PEO Extended Release Hydrophilic Matrices and their Response to Ionic Environments.

Investigate the extended release behaviour of compacts containing mixtures of hydrophilic HPMC and PEO in hydrating media of differing ionic strengths. The extended release behaviour of various HPMC:PEO compacts was investigated using dissolution testing, confocal microscopy and magnetic resonance imaging, with respect to polymer ratio and ionic strength of the hydrating media. Increasing HPMC content gave longer extended release times, but a greater sensitivity to high ionic dissolution environments. Increasing PEO content reduced this sensitivity. The addition of PEO to a predominantly HPMC matrix reduced release rate sensitivity to high ionic environments. Confocal microscopy of early gel layer development showed the two polymers appeared to contribute independently to gel layer structure whilst together forming a coherent and effective diffusion barrier. There was some evidence that poorly swollen HPMC particles added a tortuosity barrier to the gel layer in high ionic strength environments, resulting in prolonged extended release. MRI provides unique, non-invasive spatially resolved information from within the HPMC:PEO compacts that furthers our understanding of USP 1 and USP 4 dissolution data. Confocal microscopy and MRI data show that combinations of HPMC and PEO have advantageous extended release properties, in comparison with matrices containing a single polymer.

High performance disulfonated poly(arylene ether sulfone)/poly(ethylene oxide) composite membrane used as a novel separator for supercapacitor with neutral electrolyte and activated carbon electrodes

High performance disulfonated poly(arylene ether sulfone)/poly(ethylene oxide) (SPAES/PEO) composite membranes were prepared by a simple method such as a novel separator saturated by the lithium sulfate (Li2SO4) aqueous electrolyte for application in supercapacitors (SCs). As prepared composite membranes exhibit excellent mechanical properties and thermal stabilities, which are beneficial for the safety in potential applications, meanwhile, the addition of PEO on membrane also enhanced the affinity with electrolyte and the ion conduction for lithium salts. In addition, the SC cell was fabricated with optimized SPAES/PEO composite membrane and activated carbon electrodes with Li2SO4 aqueous electrolyte. The obtained SC with the SPAES/PEO separator revealed a specific capacitance of 142.5 F g−1 at a current density of 0.1 A g−1. Furthermore, the energy density of the SC was promoted to 19.04 Wh kg−1 due to the wide working voltage range of the neutral electrolyte, and the SC exhibited an excellent coulombic efficiency of almost 99% and nearly 100% cycling retention after 5000 galvanostatic charge/discharge cycles. All of these results indicated that SPAES/PEO composite membrane is suitable as a novel separator for SC.

Macroporous MgO monoliths prepared by sol–gel process with phase separation

Macroporous MgO monoliths were prepared with magnesium chloride (MgCl2·6H2O) as a precursor, poly(ethylene oxide) (PEO) as a phase-separation inducer, and propylene oxide (PO) as a gelation agent via sol–gel processing. Based on the results of differential thermal analysis (TG-DTA), Fourier transform infrared (FT-IR) spectroscopy, X-ray diffractometry (XRD), and scanning electron microcopy (SEM), the effects of PEO addition on sinterability and microstructure of the monoliths were discussed. It was found that the amount of PEO should be within a certain range, within which the gel skeletons were gradually strengthened, three-dimensional interconnective macroporous structures were resulted and the porosity of the sintered specimens obviously increased with increasing PEO addition. Furthermore, the surfaces of MgO particles were coated with some cylindrical fibres ranged from 800nm to 2µm in diameter, and the quantity of the fibres is proportional to the PEO addition.

Fabrication of poly(glycerol sebacate) fibrous membranes by coaxial electrospinning: Influence of shell and core solutions

Although poly(glycerol sebacate) (PGS) has enjoyed great success in soft tissue engineering, it remains challenging to fabricate PGS fibers. In this study, coaxial electrospinning, in which polylactide (PLA) was used to confine and draw PGS prepolymer, was used to fabricate PGS fibrous membranes. Specifically, effects of adding poly(ethylene oxide) (PEO), which was removed prior to curing, in the shell were investigated. Transmission and scanning electron microscopy were used to confirm core–shell structure and morphology of fibers, respectively. Both the removal of PEO or PLA in the shell and the efficacy of PGS curing were verified by Fourier transform infrared spectroscopy and differential scanning calorimetry. Mechanical properties of the membranes with different shell and core contents were examined. We found that the addition of PEO to the shell reduced Young׳s modulus of the resulting cured membrane and increased its elongation at break significantly, the latter indicating better PGS curing. Moreover, with the addition of PEO, increasing PGS prepolymer concentration further increased the elongation at break and appeared to enhance the structural integrity of fibers; PGS fibrous membranes (with no PLA shell) were thus successfully fabricated after the removal of PLA. The Young׳s modulus of the PGS fibrous membrane was ~0.47MPa, which is similar to that of PGS solid sheets and some soft tissues. Finally, the cytocompatibility of the electrospun membranes was validated by Alamar blue and LDH assays.

Thermal degradation of poly(3-hydroxybutyrate)/poly(ethylene oxide) blends: Thermogravimetric and kinetic analysis

Thermal stability of poly(3-hydroxybutyrate)/poly(ethylene oxide) (PHB/PEO) blends has been investigated by non-isothermal thermogravimetry in an inert atmosphere. PHB/PEO blends were prepared by hot-melt extrusion. Neat polymers decompose in one stage and PHB/PEO blends in two degradation stages, respectively. It was found that the degradation of investigated blends starts at lower temperatures and occurs more slowly by addition of PEO, that could be an indication of PEO’s destabilising effect on PHB. Kinetic analysis of the non-isothermal degradation of PHB/PEO blends was performed using isoconversional Friedman (FR) method in combination with the multivariate non-linear regression method. The kinetic analysis indicated three-stage degradation mechanism for all investigated samples, except for PEO sample which showed two-stage degradation mechanism. PEO showed higher value of activation energy confirming its superior thermal stability to PHB.

Study on the Preparation of PAMAS/PEO Fibrous Membranes by Electrospinning

Poly (aniline-co-2-methoxy aniline-5-sulfonic acid) (PAMAS) was synthesized by an oxidative polymerization in this paper. The resulted copolymer was characterized by Fourier transform infrared spectroscopy and UV-vis spectroscopy, respectively. The PAMAS fibrous membranes and PAMAS/PEO fibrous membranes were prepared via electrospinning. The influence of the molecular weight of PEO and the ratio of PAMAS/PEO in spinning solution on the fibrous morphology was studied. The results showed that PAMAS has fiber-forming ability separately. The addition of PEO was helpful to the the electrospinning of PAMAS. With the increasing of PEO’s molecular weight, the average diameter of the PAMAS/PEO fibers increased. With the increasing of PAMAS content, the fibrous average diameter has an increasing tendency.

Understanding the Impact of Poly(ethylene oxide) on the Assembly of Lignin in Solution toward Improved Carbon Fiber Production.

Carbon fiber produced from lignin has recently become an industrial scalable product with applications ranging from thermal insulation to reinforcing automobile bodies. Previous research has shown that mixing 1-2 wt %, of poly(ethylene oxide) (PEO) with the lignin before fiber formation can enhance the properties of the final carbon fibers. The research reported here determines the impact of adding PEO to a lignin solution on its assembly, focusing on the role of the lignin structure on this assembly process. Results indicate the addition of PEO anisotropically directs the self-assembly of the hardwood and softwood lignin by lengthening the cylindrical building blocks that make up the larger global aggregates. On the other hand, results from an annual lignin exhibit a shapeless, more complex structure with a unique dependence on the PEO loading. These results are consistent with improved carbon fibers from solutions of lignin that include PEO, as the local ordering and directed assembly will inhibit the formation of defects during the carbon fiber fabrication process.

Mechanical properties and chemical resistance of electrospun polyterafluoroethylene fibres

A very small addition of PEO during electrospinning led to fibrous PTFE membranes with excellent mechanical properties and chemical resistance.

X-RD, SEM, FT-IR, DSC Studies of Polymer Blend Films of PMMA and PEO

Poly (methylmetacrylate)-Poly(ethylene oxide) (PMMA-PEO) polymers blend films were prepared using the solution casting method. The polymer thin films were characterized by X-ray difraction (XRD), Scanning Electron Microscopy (SEM), FTIR and differential scanning calorimetry (DSC) technique. The amorphous or crystalline nature of polymers has been confirmed by XRD analysis. The PMMA surface morphology shows rough surface and micro pore structure. Appearance of rough surface in SEM micrograph of pure PEO was suggested several crystalline domains. The surface morphology changes severely when PEO added to PMMA polymer, which shows the development of surface morphology from smooth to rough with increasing of PEO concentration in PMMA. FT-IR data shows that some of the bands found to be shifted and intensities of some of the bands are decreased and some are disappeared with the addition of PEO to PMMA when compared to pure PMMA and PEO, which suggests the coordination/ interaction between PMMA and PEO matrixes. DSC results showed that the melting temperatures (Tm) of PMMA and PEO blend decreases when compared to pure PEO, PMMA.

High stable Li-air battery cells by using PEO and PVDF additives in the TEGDME/LiPF6 electrolytes

An ether based electrolyte containing TEGDME/LiPF6 was optimized, which possessed low viscosity and high ionic conductivity, under dry argon atmosphere in a glove box. In order to prevent air breathing cathode clogging by lithium oxide and provide stability of Li metal anode, different types in varying quantities of polymeric additives such as PEO and PVDF were added into TEGDME/LiPF6. These additives are thought to promote the dissolution of lithium peroxide precipitates formed in course of discharge process and protect the anode. Graphene/α-MnO2 nanocomposite air breathing structure coated on nickel mesh was used as cathode. A lithium disk was used as anode while glass fiber was used as the separator in ECC-Air test cells. The cells were cyclically tested using 0.1 mA/cm2 current density over a voltage range of 2.15–4.25 V. Electrochemical impedance spectroscopy (EIS) measurements was applied to investigate the effect of the polymeric additives on the resistivity of the electrolyte. Results revealed that polymer contained electrolyte structures with PVDF addition provided not only good discharge capacity but also excellent stability. After the electrochemical cycling test, the morphologies of the cathodes were analyzed using scanning electron microscopy (SEM), X-ray diffraction (XRD) analysis, and Raman spectroscopy to determine the reaction products.

Poly(ethylene oxide)-Assisted Macromolecular Self-Assembly of Lignin in ABS Matrix for Sustainable Composite Applications

In this effort, we report the compatibilization of biomass-derived lignin polymer in acrylonitrile butadiene styrene (ABS) thermoplastic matrix without loss of mechanical properties via poly(ethylene oxide) (PEO)-mediated macromolecular self-assembly. ABS was blended with lignin in different concentrations, and blends with 10 wt % PEO (relative to lignin) were prepared. The relative tensile strength improved slightly at low lignin content but diminished rapidly as the lignin content was increased. However, the inclusion of PEO as an interfacial adhesion promoter helped avoid deleterious effects. Dynamic mechanical analysis showed that PEO plasticized the hard phase and thus lowered the activation energy (Ea) for its relaxation but caused stiffening of the soft phase and increased its Ea. Microscopy revealed that incorporating lignin in ABS led to the statistical dispersion of discrete lignin domains (300–1000 nm) which, after PEO addition, were reduced to smaller interconnected particles (200–500 nm). The...

Coal Flotation Improvement Through Hydrophobic Flocculation Induced by Polyethylene Oxide

ABSTRACTPolyethylene oxide (PEO) is an efficient flocculant for the settling of various minerals including coal, quartz, and phyllosilicate. However, it is rarely used in coal flotation. In this research, the flotation of a bituminous coal with PEO addition was investigated. It was found that PEO worsened the flotation performance in tap water. But it significantly improved the flotation in the sodium hexametaphosphate solution. The tube-settling experiments, floc observation and Zeta potential analysis indicated that the sodium hexametaphosphate hindered the flocculation of kaolinite so coal was selectively flocculated.

Improved Electrochemical Performance of Lithium Air Batteries with N-Methyl-2-Pyrrolidone Based Composite Polymer Electrolytes

Lithium air batteries are able to have higher energy density because of the lighter cathode and the fact that oxygen is freely available in the environment. This causes a great interest on these type of batteries. However, the performance of Li-air batteries is affected by many factors such as type of catalysts and electrolyte composition. The stability of electrolytes is a significant limitation for cycle life performance in Li-air batteries. In recent years, most efforts have focused on the development of stable electrolytes to improve cycle life and capacity of rechargeable Li-air batteries. Therefore, stability of the polymer composite electrolytes against the reduced oxygen species generated during the discharge process was investigated. Since Li2O2 is generated at the cathode surface during cycling, an investigation of the thermal stability, conductivity and resistance of electrolytes with Li2O2 was conducted. The other challenge of the stability of Li-air batteries is degradation of lithium anode. For this reason, great efforts of this study focused on improving lifetime and recycleability through, obtaining stable electrolyte with polymeric and inorganic additives. For this aim, 1 M LiPF6 and LiBF4 salts dissolved in N-methyl-2-pyrrolidone (NMP) aprotic solvent and selected amount of polyvinylidene fluoride (PVDF) and polyethylene oxide (PEO), which is mostly used as binders for air electrodes in Li-air batteries and Al2O3 nanoparticles added into the electrolyte to improve thermal stability, provide highly reversible Li-O2 reaction during charging/discharging and prevent clogging of the porous structure of the cathode. In order to investigate electrochemical performance of the produced nanocomposite electrolytes, ECC-Air test cell was assembled in Ar-filled glove box. The lithium foil was used as anode, Sigracet 24BC gas diffusion layer (GDL) was used as the cathode and prepared nanocomposite solutions were used as the electrolyte. The anode and cathode was separated with a glass fiber separator. Differential scanning calorimetry (DSC) and derivative thermagravimetry (TG) measurements were used for thermal stability studies for the electrolytes. The cells were cyclically tested using 0.1 mA/cm2 current density over a voltage range of 2.15–4.1 V. Electrochemical impedance spectroscopy (EIS) measurements was carried out to investigate the effect of the PVDF, PeO and Al2O3 additives on the resistivity of the electrolyte. After the electrochemical cycling test, the surface of the cathode (GDL) was characterized using environmental scanning electron microscopy, X-ray diffraction patterns and Raman spectroscopy to investigate deposited lithium compounds such as LiO2, Li2O2 and Li2CO3 on the cathode during cycling test.