Amount Of PEO Research Articles

Intercalation and Confinement of Poly(ethylene oxide) in Porous Carbon Nanoparticles with Controlled Morphologies

Polymers confined at the nanometer scale often exhibit a distinct structural and dynamical response compared to their bulk counterparts. In this study, we observe that the confinement of poly(ethylene oxide) (PEO) in the nanopores of carbon nanoparticles (CNPs) leads to the suppression of crystallization and to a significant reduction of the ΔCp at the glass transition. We ask whether these changes are dominated by interfacial interactions (van der Waals type) or by geometrical constraints. For pore diameters below 2 nm (micropores following IUPAC nomenclature), we find that the larger the pore surface, the higher the amount of PEO intercalated in the micropores and, consequently, the larger the reduction of the ΔCp at the glass transition (up to 50%). For pore diameters in the range 2–50 nm (mesopores), larger pore surfaces lead to a higher amount of PEO adsorbed on the mesopore walls and the smaller the reduction of the ΔCp at the glass transition. Under these conditions of spatial confinement at the na...

Nano-web structures constructed with a cellulose acetate/lithium chloride/polyethylene oxide hybrid: Modeling, fabrication and characterization

Electrospun nano-web structures (ENWSs) were successfully fabricated from ionized binary solution of celluloseMn30/polyethylene oxideMn200 (CA/PEO of 0.5–1.5). Final concentration of polymers was 12% (w/v) in the solution, and lithium chloride was used as ionizing agent. Response surface methodology (RSM) was applied to the optimize fabrication of ENWSs. Results of multiple linear regression analysis revealed that the solution properties and ENWSs morphology were strongly influenced by CA/PEO. An increase in PEO amount increased the viscosity which is a function of molecular weight, and as a result raised the entanglement of polymeric solution but decreased the surface tension that all support nanofibers fabrication. The size of nanofibers decreased with reducing PEO and LiCl concentration. Increasing the content of LiCl promoted the electrical conductivity (EC) value; however, junction zones were formed. The overall optimum region was found to be at combined level of 1.5% CA/PEO and 0.49% (w/v) LiCl.

Investigation of Kinetic Hydrate Inhibition Using a High Pressure Micro Differential Scanning Calorimeter

Methane hydrate formation and decomposition were investigated in the presence of the kinetic inhibitor (Luvicap EG) and synergist (polyethylene oxide; PEO) using a high pressure micro-differential scanning calorimeter (HP-μDSC) with both temperature ramping and isothermal temperature programs. These investigations were performed using small samples in four different capillary tubes in the calorimeter cell. When the isothermal method was employed, it was found that Luvicap EG significantly delays the hydrate nucleation time as compared to water. The results obtained from the ramping method demonstrated that in the presence of Luvicap EG hydrate nucleation temperature was reduced. However, the presence of Luvicap EG promoted the extent of hydrate formation once nucleation had occurred. The addition of a small amount of PEO enhanced the nucleation inhibition capability of Luvicap EG further and decreased the promotion of hydrate growth. Additionally, hydrate formed in the presence of inhibitor decomposed at ...

Electrical and Electrochromic Characterization of Poly(ethylene Oxide)/Molybdenum Doped Vanadium Pentoxide Films

The hybrid guest-host nanocomposite films based on poly (ethylene oxide) (PEO) and molybdenum doped vanadium pentoxide (V0.975Mo0.025)2O5nH2O were prepared by sol-gel and hydrothermal reaction via a two-part process. The electrical properties along and across V-O layers have been evaluated. The results indicate that the proper amount of PEO can increase the electrical conductivity of the films. The electrochromism of the films were investigated by cyclic voltammetry, the ex-situ transmission spectra and photographs. The films display a reversible multichromism (orangegreenbluebrown) upon Li+ion insertion/extraction.

Optimizing ZnO nanoparticle surface for bulk heterojunction hybrid solar cells

The performance of hybrid solar cells composed of polymer and ZnO is mainly hindered by the defects of ZnO. Here, we investigate the effects of ZnO nanoparticle surface modification with poly(ethylene oxide) (PEO) on the performance of bulk heterojunction hybrid solar cells based on poly[2-methoxy-5-(2′-ethyl-hexyloxy)-1,4-phenylene vinylene] (MEH-PPV) and ZnO nanoparticles. The reference device using ZnO nanoparticles as electron acceptor shows an open-circuit voltage (VOC) of 0.83V, a short-circuit current (JSC) of 3.00mA/cm2, a fill factor (FF) of 0.46 and a power conversion efficiency (PCE) of 1.15%. After modification with very small amount of PEO, the PCE will be enhanced, which is attributed to less surface traps of ZnO nanoparticles with PEO modification. With optimized PEO (0.05%) modified ZnO nanoparticles as electron acceptors, the device typically shows a VOC of 0.86V, a JSC of 3.84mA/cm2, a FF of 0.51 and a PCE of 1.68% due to less recombination loss of carriers, smaller series resistance, and improved electrical coupling between ZnO nanoparticle and MEH-PPV. However, further increase of PEO content to 0.3% will deteriorate device performance.

Agarose Hydrogels Embedded with pH-Responsive Diblock Copolymer Micelles for Triggered Release of Substances

Hybrid agarose hydrogels embedded with pH-responsive diblock copolymers micelles were developed to achieve functional hydrogels capable of stimulus-triggered drug release. Specifically, a well-defined poly(ethylene oxide) (PEO)-based diblock copolymer, PEO-b-poly(2-(N,N-diisopropylamino)ethyl methacrylate) (PEO(113)-b-PDPAEMA(31), where the subscripts represent the degrees of polymerization of two blocks), was synthesized by atom transfer radical polymerization. PDPAEMA is a pH-responsive polymer with a pKa value of 6.3. The PEO(113)-b-PDPAEMA(31) micelles were formed by a solvent-switching method, and their pH-dependent dissociation behavior was investigated by dynamic light scattering and fluorescence spectroscopy. Both studies indicated that the micelles were completely disassembled at pH = 6.40. The biocompatibility of PEO(113)-b-PDPAEMA(31) micelles was demonstrated by in vitro primary cortical neural culture. Hybrid agarose hydrogels were made by cooling 1.0 wt % agarose solutions that contained various amounts of PEO(113)-b-PDPAEMA(31) micelles at either 2 or 4 °C. Rheological measurements showed that the mechanical properties of gels were not significantly adversely affected by the incorporation of diblock copolymer micelles with a concentration as high as 5.0 mg/g. Using Nile Red as a model hydrophobic drug, its incorporation into the core of diblock copolymer micelles was demonstrated. Characterized by fluorescent spectroscopy, the release of Nile Red from the hybrid hydrogel was shown to be controllable by pH due to the responsiveness of the block copolymer micelles. Based on the prominent use of agarose gels as scaffolds for cell transplantation for neural repair, the hybrid hydrogels embedded with stimuli-responsive block copolymer micelles could allow the controlled delivery of hydrophobic neuroprotective agents to improve survival of transplanted cells in tune with signals from the surrounding pathological environment.

Enhanced sensitivity azimuthally controlled grating-coupled surface plasmon resonance applied to the calibration of thiol-poly(ethylene oxide) grafting

Azimuthally controlled grating-coupling surface plasmon resonance (φ≠0° GC-SPR) is known to exhibit refractive index sensitivity (SRI) up to one order of magnitude higher with respect to classic φ=0° GC-SPR. Here, grated gold surfaces (period of 500nm and amplitude of 40nm) were covered with different amounts of thiol-poly(ethylene oxide) (PEO, Mw 5kDa) through a 24h functionalization process using polymer solutions at increasing concentration (from 500nM to 2.5mM). The GC-SPR output signal generated by each PEO layer was measured in both null and rotated configuration. The number of PEO molecules adsorbed onto each surface (cm−2) and the corresponding molecular surface densities (σ [ng/cm2]) were calculated from the angle shifts collected after PEO film formation, by combining the model shown by Jung and the theory of PEO layer formation. In the end, we obtained a calibration curve that correlates the amount of PEO tethered onto the surface with the SPR measurement output signal, that will be useful for future reference. At the PEO surface saturation condition (PEO σ=592ng/cm2, obtained using PEO concentration ≥2mM), a SRI of 603°/RIU was reached (φ=45°), which is ≈10-fold higher than what obtained through the classic GC-SPR (φ=0°). This enhanced instrumental sensitivity allowed detecting tiny amounts of molecules adsorbed onto the surface (3.1ng vs 59.7ng of classic φ=0° GC-SPR), a property that is extremely valuable for the application of SPR sensing to quantitative determinations.

Conductivity Studies on Filler Free and Filler Doped PVA-PEO Based Blend Polymer Electrolytes

The present study deals with the investigation of conduction behavior of filler free and filler based blend electrolyte system. The polymer blend films consisting of PVA and PEO doped with silver salt and PEG plasticizer, are prepared using solution cast technique. The filler free system is prepared for varying ratios of host polymers (PVA: PEO); whereas the filler based system is prepared with various Al2O3 concentrations in the blend films. The conductivity studies of prepared samples are carried out using impedance spectroscopic analysis. The conductivity for the filler free blend system is found to increase with increasing amount of PEO in all the blend specimens. On the other hand, the filler based system shows the conductivity enhancement upto 6wt% which mitigates with further addition of filler into the electrolytes. The DSC scans are found to support the conductivity results.

Effect of Properties of Polyimide Fiber Paper-Based Materials by Different Paper-Making Process

Polyimide fibers and polyamide acid fibers was used as main materials to produce Polyimide fiber paper. A certain amount of PEO and aramid pulp was added and the sheet was treated by immersion and hot pressing in specified process. The experimental results showed that when the dosage of PEO and aramid pulp were 0.06% and 6% respectively, the sheet tended to present more excellent strength properties and electrical performance compared with sheet using single polyimide fibers as the main fiber materials.

Fusion of poly(vinyl acetate-b-vinyl alcohol) spherical micelles in water induced by poly(ethylene oxide)

Rapid and reversible morphology changes in aqueous dispersions of amphiphilic block copolymers are important for the development of complex fluids with switchable bulk properties. In this communication, we report the unusual ability of poly(ethylene oxide) to induce the fusion of spherical poly(vinyl acetate-b-vinyl alcohol) (PVAc-b-PVA) amphiphilic block copolymer micelles in water. While PVAc-b-PVA block copolymer micelles (diameters ∼22–25 nm) undergo depletion–flocculation upon addition of large amounts of 11 kg mol−1 PEO homopolymer (30.7 wt% in H2O), addition of relatively small amounts of PEO (3.1 wt% in the final dispersion) triggers their fusion into worm-like micelles. Diluting the worm-like micelle dispersions with pure water induces their reversion to spherical micelles. We suggest two tentative mechanisms for this morphology change induced by PEO homopolymer addition.

Preparation of highly porous gastroretentive metformin tablets using a sublimation method

The present investigation is aimed to formulate floating gastroretentive tablets containing metformin using a sublimation material. In this study, the release of the drug from a matrix tablet was highly dependent on the polymer concentrations. In all formulations, initial rapid drug release was observed, possibly due to the properties of the drug and polymer. The effect of the amount of PEO on swelling and eroding of the tablets was determined. The water-uptake and erosion behavior of the gastroretentive (GR) tablets were highly dependent on the amount of PEO. The water-uptake increased with increasing PEO concentration in the tablet matrix. The weight loss from tablets decreased with increasing amounts of PEO. Camphor was used as the sublimation material to prepare GR tablets that are low-density and easily floatable. Camphor was changed to pores in the tablet during the sublimation process. SEM revealed that the GR tablets have a highly porous morphology. Floating properties of tablets and tablet density were affected by the sublimation of camphor. Prepared floating gastroretentive tablets floated for over 24h and had no floating lag time. However, as the amount of camphor in the tablet matrix increased, the crushing strength of the tablet decreased after sublimation. Release profiles of the drug from the GR tablets were not affected by tablet density or porosity. In pharmacokinetic studies, the mean plasma concentration of the GR tablets after oral administration was greater than the concentration of glucophase XR. Also, the mean AUC0–∞ values for the GR tablets were significantly greater than the plasma concentrations of glucophase XR.

Specific features of the mass transfer of the liquid component in poly(ethylene terephthalate) crazing in poly(ethylene oxide) solutions

area. During crazing, the emerging porous structure is being filled with the surrounding liquid; therefore, in the course of the decrease in the polymer porosity, a part of the liquid trapped in the bulk of the polymer early in the stretching seeps to the environment (a phenomenon of syneresis). In other words, during crazing, the mass transfer of the liquid component reverses; namely, its ingress into the bulk of the polymer early in the stretching is replaced by its migration from the pore space at the stage of the collapse of the porous structure. Naturally, these structural rearrangements cause the extremal behavior of the porosity W of the crazed polymer as a function of the polymer strain e in the adsorptive medium (Fig. 2). In this work, we made the first attempt to study spe� cific features of the mass transfer of PEO dissolved in an adsorptive medium in the course of PET crazing in PEO solutions. Figure 3 presents the PEO content of the crazed nanoporous PET matrix versus strain e. Figure 3 shows that the amount of PEO incorporated in the fibrous porous structure of the crazed polymer depends on the PET strain in PEO solutions and on their molecular weight. It proved that the amount of relatively low�

Sodium alginate/poly (ethylene oxide) blend hydrogel membranes for controlled release of valganciclovir hydrochloride

Sodium alginate (SA) and poly (ethylene oxide) PEO blend membranes were prepared by solvent casting method for the controlled release of valganciclovir hydrochloride, an antiHIV drug. The prepared membranes were thin, flexible, smooth, and characterized by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimeter (DSC), X-ray diffraction (X-RD), scanning electron microscopy (SEM), and tensile strength measurement. FTIR was used to understand the formation of hydrogen bonding between SA and PEO. The DSC and X-RD studies were performed to understand the crystalline nature of drug after encapsulation into the membranes. SEM was used to study the surface morphology of the membranes. Tensile strength measurements revealed the mechanical strength of the membranes. In vitro release studies indicated a dependence of release rate on the extent of crosslinking, amount of drug loading, and the amount of PEO, but slow release rates was extended up to 12 h. Cumulative release data were fitted onto to an empirical equation to compute diffusional exponent (n), which indicated the nonFickian trend for drug release.

Development and evaluation of a chronotherapeutic drug delivery system of torsemide

The objective of this study was to prepare and evaluate chronotherapeutic drug delivery systems (ChrDDs) of torsemide. Compression coated tablets (CCT) containing torsemide in the core tablet were prepared by the compression coating technique with different grades of polyethylene oxide (PEO WSR 301 & 1105). The optimized formulations were characterised for tabletting parameters and drug polymer interaction by Fourier-Transform Infrared Spectroscopy (FTIR).The hardness of all the CCT using PEO WSR 301 & PEO WSR 1105 were in the range 6-8 kg/cm² & 5.5 to 7 kg/cm² respectively. Their friability values were <0.3%. All the CCT showed a clear lag time but finalized as per the predetermined lag time. As the amount of PEO was increased in the outer layer the drug released was delayed. The drug content of all the CCT was >99%. The FTIR studies showed no interaction throughout the process of development. Formulations of F7 and of P7 were considered optimized formulations since they yielded a predetermined lag time of 6h before burst release. Hence, these formulations can be exploited to achieve chronotherapeutic drug delivery systems of Torsemide for the treatment of hypertension at the time the patient needs it.

Evaluation of Physical Properties as Magnesium Stearate Blendedin Hydrophilic Matrix Tablets

ABSTRACT − Main objectives of this study were to investigate the effects of a lubricant, magnesium stearate, as blended in a hydrophilic matrix tablet and to identify significant factors using a tablet ejection force and a swelling property. The characteristics of tablet ejection were evaluated with three different compression forces (30, 40, and 60 MPa) and two controlled factors, amount of magnesium stearate and its mixing time. A hydrophilic model drug (terazosin HCl dihydrate) was regarded as a default factor. Tablet swelling was also evaluated. The optimal amount of PEG compared to PEO was set to be 88.50% w/w. As the amount of magnesium stearate was varied from 0.79% to 2.20% w/w, the amount of PEO and PEG was adjusted to meet the tablet’s total weight while maintaining the ratio between the two excipients constant. As the mixing time of magnesium stearate was increased, the tablet ejection force and the swelling property were decreased. As the amount of magnesium stearate was increased, the tablet ejection force and the swelling property were decreased since the increased mixing time and the amount of magnesium stearate induced hydrophobic properties of the matrix tablet more effectively. The ejection force of the tablet increased as a result of increase in the compression force, which means that the breaking of tablet/die-wall adhesion energy was also increased when the compression energy was increased. The results gavea valuable guide how to choose suitable amount of the lubricant with processing conditions for the development of hydrophilic matrix formulations. Key words− Lubricant, Ejection force, Matrix tablet, Swelling kinetics, Hydrophilic swellable polymer

Confinement Effects of Silica Nanoparticles with Radii Smaller and Larger than Rg of Adsorbed Poly(ethylene oxide)

The properties of polymers on nanoparticles are different than those of the bulk, so that the interphase region becomes more important as the surface/volume ratio of the nanoparticles increases. Knowledge of the modified polymer properties is relevant both in nanocomposite applications and for nanoparticles in suspension. Polymers have chain dimensions (characterized by the radius of gyration, Rg) similar to the nanoparticles (Rnanoparticle) themselves, so that chain conformation, mobility and crystallinity can be affected by Rg/Rnanoparticle. Here, both the glass transition temperature (Tg) and degree of crystallinity (Xc) of poly(ethylene oxide) (PEO) on individual SiO2 nanoparticles of nominal 15, 50, and 100 nm diameter (2RSiO2), in which Rg(PEO) was greater, equal to, or less than RSiO2 was investigated. Plateau adsorption of PEO on SiO2 nanoparticles (PEO−SiO2) increased in the order PEO−SiO2 (100 nm) > PEO−SiO2 (50 nm) > PEO−SiO2 (15 nm). At plateau adsorption, after melting and solidification, the samples were completely amorphous. The Tg of the adsorbed PEO increased in the order PEO−SiO2 (100 nm) > PEO−SiO2 (50 nm) > PEO−SiO2 (15 nm); since the Tgs were above 25 °C in all cases, the PEO behaved more like a brittle solid than an elastomer. For comparable amounts of PEO that were adsorbed from solution but not melted, the melt endotherm increased in the order PEO−SiO2 (15 nm) > PEO−SiO2 (50 nm) > PEO−SiO2 (100 nm). These trends were interpreted as due to an increase in loop/tail lengths and thus flexibility of the PEO chains, with a concomitant ability to crystallize, as Rg (PEO)/RSiO2 nanoparticles increased and which was the result of less hydrogen bond formation between the oxygens of PEO and the silanols (SiOH) of the SiO2 as the nanoparticle size decreased. This in turn was attributed to the energetically unfavorable conformations necessary for the PEO chains to adopt in order to hydrogen bond with silanols on the smaller nanoparticles.

Development and Optimization of a Novel Sustained-release Tablet Formulation for Bupropion Hydrochloride using Box-Behnken Design

【The objectives of this study were to evaluate the effect of formulation ingredients on the drug release and to optimize the novel sustained release matrix tablet formulations of bupropion hydrochloride. A three factor, three-level Box-Behnken design was used for the optimization procedure, with the amounts of PEO ( $X_1$ ), citric acid ( $X_2$ ) and Compritol 888 ATO ( $X_3$ ) as the independent variables. The selected dependent variables were the cumulative percentage values of bupropion hydrochloride that had dissolved after 1, 4 and 8 hr. Various dissolution profiles of the drug from sustained release matrix tablets were obtained. Optimization was performed for $X_1$ , $X_2$ and $X_3$ using the following target ranges; $30%{\leq}Y_1{\leq}45%$ ; $70{\leq}Y_2{\leq}85%$ ; $85%{\leq}Y_3{\leq}100%$ . The optimized formulation for bupropion hydrochloride was achieved with 12.5% PEO ( $X_1$ ), 2.5% citric acid ( $X_2$ ) and 10% Compritol 888 ATO ( $X_3$ ). The sustained release matrix tablets with the optimized formulation provided a release profile that was close to predicted values. In addition, the dissolution profiles of the sustained release matrix tablet with the optimized formulation were similar to those of the commercial product Wellbutrin $^{(R)}$ SR tablets ( $f_2$ =79.8 79.83).】

Polymer induced condensation of DNA supercoils

Macromolecular crowding is thought to be a significant factor driving DNA condensation in prokaryotic cells. Whereas DNA in prokaryotes is supercoiled, studies on crowding-induced DNA condensation have so far focused on linear DNA. Here we compare DNA condensation by poly(ethylene oxide) for supercoiled and linearized pUC18 plasmid DNA. It is found that supercoiling has only a limited influence on the critical amount of PEO needed to condense plasmid DNA. In order to pack DNA supercoils in condensates, it seems inevitable that they must be deformed in one way or another, to facilitate dense packing of DNA. Analytical estimates and Monte Carlo simulations indicate that packing of DNA supercoils in condensates is most likely facilitated by a decrease of the superhelical diameter rather than by unwinding of the supercoils.

Low environmental sensitive antistatic material based on poly(vinyl chloride)/quaternary ammonium salt by blending with poly(ethylene oxide)

AbstractA quaternary ammonium salt (QAS) was synthesized and characterized by 1H NMR. A low environmental sensitive antistatic plasticized poly(vinyl chloride) (PPVC) was prepared by blending with QAS and poly(ethylene oxide) (PEO). The structure and properties of PPVC/QAS/PEO blend were studied by scanning electronic microscope (SEM), surface resistivity, and mechanical properties tests. The results show that the surface resistivity of PPVC/QAS/PEO (100/4.5/0) blend without PEO component can be reduced to less than 3.0 × 108 Ω at 65% environmental humidity, which satisfied the antistatic property requirement related to MT113‐1995 of China. However, QAS, similar to other commercial antistatic agents, is much sensitive to environmental humidity. When a small amount of PEO is added, the surface resistivity of PPVC/QAS/PEO blend has a quite low sensitivity to environmental humidity and further reduces. An excellent antistatic property of PPVC/QAS/PEO blend under low humidity can be achieved. Its tensile strength and elongation at break are also improved with PEO addition. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Component Terminal Dynamics in Poly(ethylene oxide)/Poly(methyl methacrylate) Blends

The rheological response of high molecular weight tracer chains of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA), separately blended with low molecular weight PEO/PMMA matrices of varying composition, were obtained over a 120 deg temperature window. Monomer friction factors, ζ, for each component as a function of temperature and matrix composition were extracted by various means, all of which yielded consistent results. The tracer diffusivities of low molecular weight PEO chains in some of the same blends were obtained by forced Rayleigh scattering, and the resulting friction factors agree well with those obtained using rheology. The overall results show that the mobilities of both PMMA and PEO are strongly composition-dependent in PMMA-rich blends, their monomeric friction factors dropping precipitously upon addition of small amounts of PEO. The composition dependence of the PMMA ζ is strong over a wide composition range, whereas that of PEO is only significant at high PMMA content blends. Friction factors for the PEO component are significantly larger than those inferred from segmental dynamics measurements reported in the literature. The Lodge−McLeish self-concentration model, as usually applied, is unable to predict the observed behavior of either component. However, the data can be nearly quantitatively described using a simple but empirical mixing rule. Selected experiments were repeated using a PEO matrix with methoxyl rather than hydroxyl end groups; except for the change in glass transition temperature for the PEO, no significant effects were observed.