High Molecular Weight Polyethylene Oxide Research Articles

Comparing Two Electrochemical Approaches for Measuring Transference Numbers in Concentrated Electrolytes

We compare two experimental approaches for measuring the cation transference number in mixtures of polyethylene oxide (PEO) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) salt: the well-established current-interrupt method proposed by Ma et al. [J. Electrochem. Soc., 142, 1859 (1995)], and a more recent method based on measuring the steady-state current proposed by Balsara and Newman [J. Electrochem. Soc., 162, A2720 (2015)]. In electrolytes comprised of high molecular weight PEO, the data from the two techniques agree, highlighting the equivalence of these two approaches. However, in lower molecular weight PEO electrolytes the values of the two approaches diverge at low salt concentrations. We posit this is because the approach of Ma et al. requires measurements that are sensitive to the nature of the interface between the electrolyte and the electrode. The transference numbers measured by the approach of Balsara and Newman for both low and high molecular weight samples vary from 0.7 to −0.8 and are within experimental error throughout the entire salt concentration window.

Rheological effects of drag-reducing polymers improve cerebral blood flow and oxygenation after traumatic brain injury in rats

Cerebral ischemia has been clearly demonstrated after traumatic brain injury (TBI); however, neuroprotective therapies have not focused on improvement of the cerebral microcirculation. Blood soluble drag-reducing polymers (DRP), prepared from high molecular weight polyethylene oxide, target impaired microvascular perfusion by altering the rheological properties of blood and, until our recent reports, has not been applied to the brain. We hypothesized that DRP improve cerebral microcirculation and oxygenation after TBI. DRP were studied in healthy and traumatized rat brains and compared to saline controls. Using in-vivo two-photon laser scanning microscopy over the parietal cortex, we showed that after TBI, nanomolar concentrations of intravascular DRP significantly enhanced microvascular perfusion and tissue oxygenation in peri-contusional areas, preserved blood–brain barrier integrity and protected neurons. The mechanisms of DRP effects were attributable to reduction of the near-vessel wall cell-free layer which increased near-wall blood flow velocity, microcirculatory volume flow, and number of erythrocytes entering capillaries, thereby reducing capillary stasis and tissue hypoxia as reflected by a reduction in NADH. Our results indicate that early reduction in CBF after TBI is mainly due to ischemia; however, metabolic depression of contused tissue could be also involved.

Stearic acid and high molecular weight PEO as matrix for the highly water soluble metoprolol tartrate in continuous twin-screw melt granulation

Granules with release-sustaining properties were developed by twin screw hot melt granulation (HMG) using a combination of stearic acid (SA) and high molecular weight polyethylene oxide (PEO) as matrix for a highly water soluble model drug, metoprolol tartrate (MPT). Earlier studies demonstrated that mixing molten SA and PEO resulted in hydrogen bond formation between hydroxyl groups of fatty acid molecules and ether groups in PEO chains. These molecular interactions might be beneficial in order to elevate the sustained release effect of drugs from a SA/PEO matrix. This study aims to investigate the continuous twin screw melt granulation technique to study the impact of a SA/PEO matrix on the dissolution rate of a highly water soluble drug (MPT). Decreasing the SA/PEO ratio improved the release-sustaining properties of the matrix. The solid state of the granules was characterized using differential scanning calorimetry (DSC), nuclear magnetic resonance (NMR), X-ray diffraction (XRD), Raman spectroscopy, Fourier transform infrared (FTIR) and near infrared chemical imaging (NIR-CI) in order to understand the dissolution behavior. The results revealed a preferential interaction of the MPT molecules with stearic acid impeding the PEO to form hydrogen bonds with the stearic acid chains. However, this allowed the PEO chains to recrystallize inside the stearic acid matrix after granulation, hence, elevating the release-sustaining characteristics of the formulation.

Improvement of Impaired Cerebral Microcirculation Using Rheological Modulation by Drag-Reducing Polymers.

Nanomolar intravascular concentrations of drag-reducing polymers (DRP) have been shown to improve hemodynamics and survival in animal models of ischemic myocardium and limb, but the effects of DRP on the cerebral microcirculation have not yet been studied. We recently demonstrated that DRP enhance microvascular flow in normal rat brain and hypothesized that it would restore impaired microvascular perfusion and improve outcomes after focal ischemia and traumatic brain injury (TBI). We studied the effects of DRP (high molecular weight polyethylene oxide, 4000 kDa, i.v. at 2 μg/mL of blood) on microcirculation of the rat brain: (1) after permanent middle cerebral artery occlusion (pMCAO); and (2) after TBI induced by fluid percussion. Using in vivo two-photon laser scanning microscopy (2PLSM) over the parietal cortex of anesthetized rats we showed that both pMCAO and TBI resulted in progressive decrease in microvascular circulation, leading to tissue hypoxia (NADH increase) and increased blood brain barrier (BBB) degradation. DRP, injected post insult, increased blood volume flow in arterioles and red blood cell (RBC) flow velocity in capillaries mitigating capillary stasis, tissue hypoxia and BBB degradation, which improved neuronal survival (Fluoro-Jade B, 24 h) and neurologic outcome (Rotarod, 1 week). Improved microvascular perfusion by DRP may be effective in the treatment of ischemic stroke and TBI.

A Mechanistic Investigation of the TTP-like State Associated with Intravenous Abuse of Opana® ER

Background: Since 2012, a growing list of case reports has emerged describing the occurrence of a TTP-like state following intravenous (i.v.) abuse of extended release oxymorphone (Opana® ER). The pathophysiology resulting from intravenous exposure to Opana® ER has demonstrated a spectrum of severity with unclear etiology, and approaches to treatment/management have ranged from early plasma exchange to supportive care alone. As a result these cases have spurred a collaborative investigation to better understand mechanisms of toxicity. Given the temporal relation between the reformulation of the drug product to achieve extended release and the onset of reported cases, we investigated the inert ingredient mixture as a possible causal factor.Methods: Guinea pigs were used as an animal model to understand the hematopathologic and nephrotoxic potential of the inert ingredient mixture of Opana® ER, which was provided by Endo Pharmaceuticals under a research collaborative agreement. Animal studies were approved by Institutional Animal Care and Use Committees and conducted in adherence with NIH guidelines. Animals were studied over various i.v. dosing schemes (single injections of 0.1, 0.3, or repeated dosing of 0.3mg/kg (5 doses at 1.5hr intervals)) with either the entire inert ingredient mixture ("PEO+") or high molecular weight polyethylene oxide alone ("PEO")-the major constituent of the inert ingredient mixture. The dose range was based on estimates of the inert ingredient mass introduced during the adulteration and injection of the drug product. Additional in vitro and cell-based assessments of coagulation (thromboelastography, thrombin generation) and ADAMTS13 function were carried out to better understand in vivo observations.Results: Intravenous administration of the solubilized inert ingredient mixture in guinea pigs resulted in dose-dependent pathologic changes in blood parameters and kidney function. Hematological changes included a dose dependent increase in free plasma hemoglobin (Hb), decreased hematocrit and platelet count. Acute kidney injury was characterized by dose-dependent renal cortical iron deposition, plasma creatinine increase, distal convoluted tubular injury (NGAL mRNA induction), and glomerular damage (hemoglobinuria) (Table 1). At high doses, red blood cell aggregation and renal hypoxia (HIF-1 accumulation) was observed. These observations were similar following the administration of PEO alone, and occurred independent of changes to ADAMTS13 and its cleavage of Von Willebrand Factor. PEO, when spiked into blood in vitro, does not directly modulate coagulability as indicated by global assays of coagulation.Conclusions: The present animal study suggests that i.v. exposure to the inert ingredients included in Opana® ER can trigger hematologic responses resembling elements of TTP, namely intravascular hemolysis and acute renal injury/failure. However, the renal injury observed in the guinea pig model is distinct from classic TTP, which involves spontaneous platelet clumping and subsequent microvascular thrombosis; instead, the nephrotoxicity likely arises from a multifactorial process encompassing renal tubular injury and glomerular damage, arising secondary to hemolysis, extracellular Hb/heme/iron mediated oxidative tissue damage and compromised tissue oxygenation.Table 1Guinea pig dose group(mg of PEO+/kg)Cmax of plasma free Hb [mg/ml]AUC0-24h of plasma free Hb [mg/ml x h]hematocrit at 24h [%]platelet count at 24h [K/µl]NGAL induction** (renal cortex)plasma creatinine at 24h [µmol/L]hemoglobinuria at end of study [mg/ml]iron deposition (renal cortex)[µg/g tissue]Control0.8 ±0.1 (n=4)16.2 ±4.8 (n=4)36 ±1.7 (n=5)205 ±11.6 (n=5)1 ±0.3 (n=3)87.0 ±9.3 (n=4)0.1 (n=1)33 ±3.5 (n=3)0.1 single dose1.4 ±0.6 (n=11)20.5 ±5.75 (n=11)35 ±3.1 (n=5)157 ±20.5 (n=5)1 ±0.5 (n=3)104 ±41.3 (n=4)0.6 (n=2)49 ±7.3 (n=3)0.3 single dose2 ±0.3 (n=13)36.5 ±5.1 (n=13)31 ±1.1 (n=6)135 ±11.2 (n=6)1.6 ±0.4 (n=3)145 ±36.7 (n=4)1.2 (n=2)153 ±2.5 (n=3)0.3 multi dose (5 injections at 1.5h intervals)*5.1 ±1.3 (n=5)87.8 ±15.8 (n=4)28 ±0.8 (n=4)62 ±12.4 (n=4)24 ±0.8 (n=4)421.1 ±33.8 (n=4)9.8 ±5 (n=3)139 ±9.5 (n=4)data represented as mean ±SEM, n = number of animals*endpoint 24h, all other groups 48h**Fold induction over baseline DisclosuresWong:Haemonetics Corporation: Research Funding.

Efficacy of Rebamipide Gargle against Chemotherapy-induced Oral Mucositis

Chemotherapy-induced oral mucositis (CIOM) is a severe adverse event resulting from cancer chemotherapy. Toxic free radicals and pro-inflammatory cytokines produced by anticancer drugs have been reported to be associated with CIOM. Rebamipide has been shown to increase gastric endogenous prostaglandin E2 and I2, to promote gastric epithelial mucin, and to behave as an oxygen free-radical scavenger in addition to other anti-inflammatory actions. We developed a gargle solution of rebamipide, adding ultrahydrogel for mucosal protection and to maintain rebamipide on the oral mucosa. A 300 mL rebamipide gargle solution combines 600 mg rebamipide, 3 g high molecular-weight polyethylene oxide, 1.2 g carrageenan, pineapple flavoring, and water. The efficacy of the rebamipide gargle was evaluated in 175 patients with CIOM from November 2009 to December 2012, each instructed to use the rebamipide gargle 5-6 times daily. The severity of CIOM was assessed according to the National Cancer Institute's Common Terminology Criteria for Adverse Events (CTCAE, version 4.0). Their CTCAE scores (3/2/1/0) changed from n=13/64/98/0 to 0/10/103/62, respectively, after initiation of the rebamipide gargle (p<0.01; paired t-test). The median duration to best response was 14 days (range: 1-49). CTCAE scores decreased in 132 patients (75.4%), including 62 (35.4%) who achieved grade 0. There were no unexpected safety events. Rebamipide gargle was well tolerated and demonstrated to have significant therapeutic efficacy against CIOM.

Shaken but not stirred: The formation of reversible particle – polymer gels under shear

Abstract Some dispersions of clay and silica particles in water in the presence of relatively high molecular weight polyethyleneoxide (PEO), which are fluid when at rest, become solid-like after a quick shake to such an extent that they can be held in the hand. On leaving the dispersions for a certain period of time, minutes to days depending on the polymer molecular weight and concentration, the dispersions become liquid-like again. These dispersions have been called “shake gels”, and a number of physical variables are determinant for producing the gel and controlling its behavior. In this work, we have studied the effect of the shape and size of the particles and of the PEO molecular weights. To that aim, we have mapped the “phase” behavior of silica (Ludox TM-50), montmorillonite and laponite dispersions in presence of PEO of different molecular weight. Shake gels are formed under certain concentrations of particles and PEO. The necessary degree of particle coverage for shake gel formation seems to depend on the particle shape. Whereas in the case of disc-shaped particles this limit is around the saturation concentration, in the case of spherical particles the limit is around 2/3 of the particle surface saturation. On the other hand, we observe some differences between montmorillonite (micrometer-size particles) and laponite (nanometric particles) dispersions. When we shake the former we find in some cases an important and irreversible phase separation; on the contrary, in the case of the laponite dispersions, the phase separation is far less frequent and extensive. Finally, we have found that the nature of the applied shear field has a profound effect on the sample behavior. When we place the dispersions in a conventional rheometer and shear them at moderate shear rate, for many minutes the gel is not formed. However, shaking it by hand or extruding it through a syringe brings about this effect in a matter of seconds.

Evaluation of formulation and effects of process parameters on drug release and mechanical properties of tramadol hydrocloride sustained release matrix tablets

This study investigates using of high molecular weight polyethylene oxide (PEO WSR Coagulant) for the preparation of sustained release matrix tablets containing high dose, highly water soluble drug, tramadol HCl. Proportion of PEO polymer, type of insoluble filler, proportion of tramadol HCl, amount of drug in tablet, tablet diameter and compression pressure were recognized as critical formulation and process parameters and their influence on drug release and tablet mechanical properties was evaluated. Percentages of tramadol HCl released after 30 and 240 minutes were selected for evaluation of drug release, while tensile strength was used as indicator of tablet mechanical properties. Only proportion of tramadol HCl exhibits statistically significant effect on percentages of tramadol HCl released after 30 and 240 minutes, with higher, wherein increasing of the tramadol HCl proportion increased its release rate among the evaluated variables in selected ranges. All of the investigated factors exhibit statistically significant effect on tablets tensile strength, with the largest influence of filler type. Tablets prepared with highly compressible filler (microcrystalline celullose) exhibit higher tensile strength and therefore better mechanical properties to those prepared with partially pregelatinised starch (Strach 1500).

Reducing the entrainment of clay minerals in flotation using tap and saline water

High gangue entrainment is a major problem in fine particle flotation. In this study, the entrainment of kaolinite Q38 in flotation was examined in tap and saline water. High molecular weight polyethylene oxide (PEO) was used to reduce the entrainment of kaolinite Q38 by enlarging the size of kaolinite particles in flotation. It was found that PEO reduced the entrainment significantly in flotation using tap water, but in saline water, the effect of PEO was less pronounced. The aggregation behaviour of kaolinite Q38 particles in the absence and presence of PEO and its effect on the entrainment of kaolinite Q38 were studied by the in-situ measurement of flocs and the size of enlarged particles, settling tests and the measurement of froth stability in flotation. It is interesting to find that PEO did flocculate kaolinite Q38 particles and enlarge their sizes in flotation despite high agitation. However, the reduction of the entrainment of kaolinite Q38 in flotation was dependent on the type of flocs formed and froth stability which can be modified by electrolytes in water and a high addition of PEO.

Efficacy of rebamipide-gargle for chemotherapy-induced oral mucositis.

9637 Background: Chemotherapy-induced oral mucositis (CIOM) is a severe adverse event resulting from cancer chemotherapy, and causes severe pain which impacts eating, nutrition, infection and overall quality of life. CIOM can result in unplanned treatment interruptions including dose reduction or treatment delay. Toxic free radicals and several pro-inflammatory cytokines produced by anti-cancer drugs have been reported to correlate with CIOM. Rebamipid, an endogenous inducer of prostaglandins, is widely used for gastric ulcers and gastritis in Asia. It has been shown to increase gastric endogenous prostaglandin E2 and I2, to promote gastric epithelial mucin, to behave as an oxygen–free radical scavenger, and to have other anti-inflammatory actions. In this study, we made a rebamipide gargle using rebamipide and ultrahydrogel, which is added for mucosal protection and to sustain the rebamipide on oral mucosa for a long time. Methods: The objective of this study is to evaluate the efficacy of the rebamipide gargle in relieving CIOM. Each 300ml of rebamipide gargle is made by combining rebamipide 600mg, high molecular weight polyethylene oxide 3g, carrageenin 1.2g, pineapple flavor and water. Patients were instructed to use the rebamipide gargle 5-6 times a day. The severity of CIOM was assessed according to the National Cancer Institute Common TerminologyCriteria for Adverse Events (CTCAE version 4.0). Results: From November 2009 to December 2012, 175 patients with CIOM were enrolled in this study (colorectal cancer 95 patients, breast cancer 32, gastric cancer 22, lung cancer 14, and other cancers 12). The patients’ CTCAE grades (3/2/1/0) changed from (n=13/64/98/0) to (0/10/103/62) respectively after initiation of rebamipide gargle (p&lt;.01; paired t test). A decrease in CTCAE was observed in 142 patients (81.1%) including 62 patients (35.4%) achieving grade 0. The mean duration to best response was 14 days (range: 1-49), and rebamipide gargle was continued 42 days (range: 5-970).There were no unexpected safety events. Conclusions: Rebamipide gargle was well tolerated and demonstrated significant therapeutic response for CIOM.

Direct measurement of alkaline phosphatase kinetics on bioactive paper

The reaction kinetics of alkaline phosphatase (ALP) adsorbed on paper was quantified by image analysis using a colorimetric technique under conditions of excess enzyme. A classical reaction kinetics approach integrated with image processing technique was used to analyse the coloured product formation from the enzyme substrate reaction against time. The order of reaction and rate constant of enzyme activities on paper surface were calculated. ALP was either physisorbed directly on paper or adsorbed on paper treated with a monolayer of a high molecular weight cationic polyacrylamide (CPAM), an anionic polyacrylic acid (PAA) or a high molecular weight polyethylene oxide (PEO). The reaction rate of enzymatic paper follows a first order reaction with respect to the concentration of enzyme–substrate complex. ALP immobilized on paper has a reaction rate 2 to 3 orders of magnitude lower than the free ALP enzyme in buffer solution. This might be due to a critical loss of enzyme flexibility upon adsorption. No increase in reaction rate was achieved by immobilizing ALP on paper treated with a high molecular weight cationic polyacrylamide (CPAM) or a highly charged anionic polyacrylic acid oligomer (PAA), which suggests the enzyme orientation was not significantly affected. However, the reaction rate for ALP on PEO treated paper was lower than that on CPAM or PAA treated papers. That is probably due to some PEO-enzyme interaction affecting the tertiary structure of the ALP enzyme.

Effect of viscoelasticity on liquid transfer during gravure printing

Roll-to-roll patterning of small-scale features on a rapidly moving web is an industrially important process with a wide array of commercial applications both old and new. Examples include magazine printing and more recently the pattering of flexible electronics. Among the many existing web coating techniques for large-scale fabrication, slit die and gravure coating are the most commonly used. In gravure coating, an engraved roller with a regular array of shallow cavities/cells is used to pick up fluid from a bath. It is then passed through a flexible doctoring blade in order to meter off excess fluid before printing the fluid onto a flexible substrate. Here we present an experimental investigation into the effect that viscoelasticity has on the dynamics of liquid transfer from an idealized gravure cell to a flat rigid substrate. Although the dynamics of the actual gravure coating process is quite complex, we chose to study a simplified process by imposing an extensional flow using a modified filament stretching rheometer in which one of the endplates is replaced by a cell containing a single truncated conical gravure cell. The deformation and stretching of the resulting liquid bridges, the motion of the contact line within the gravure cell and the total amount of fluid removed from the gravure cell are studied as a function of the imposed stretch rate, the fluid rheology, and the geometry of the gravure cell. Two different viscoelastic solutions of high molecular weight polyethylene oxide in water were studied and compared to a series of Newtonian fluids. The results show that the primary impact of viscoelasticity is the addition of an elastic stress which increases the tension along the liquid bridge and significantly increases the bridge lifetime. For stretches where the gravure cell was placed on the bottom and the top plate moved vertically, viscoelasticity was found to significantly reduce the amount of fluid transferred to the top plate. However, by placing the gravure cell on top and reversing the relative direction of the inertial and gravitational stresses, viscoelasticity was found to significantly increase the amount of fluid transferred. Increasing the stretch rate was found to amplify these observations. Finally, increasing the contact angle between the fluid and the gravure cell and decreasing the aspect ratio of the gravure cell were both found to increase the amount of fluid transferred.

Using atomic force microscopy to probe the adsorption kinetics of poly(ethylene oxide) on glass surfaces from aqueous solutions

This paper presents force–distance measurements using the AFM in order to study the adsorption kinetics of high molecular weight polyethylene oxide (4 million Da) with a broad molecular weight distribution onto glass surfaces. The measurements were conducted at different incubation times in the polymer solution. In 0.01 M NaCl the PEO was found to take a relatively long time (>2 days) to attain full surface coverage, during the period from the first contact of the polymer solution with the surface to full surface coverage, the range of the interaction between the two surfaces increases from around 20 nm to 130 nm, indicating slow adsorption kinetics, which can be attributed to the exchange between the adsorbed layer with the polymer molecules in solution as well as a change that might occur in the conformation of the adsorbed chains. During this period, the adhesion observed on separation of the surfaces was found to be dependant with incubation time in the PEO solution reaching its maximum value in the time frame of 29–47 h of incubation. These results seem to be different from earlier data obtained from adsorption of the PEO on the glass surface from the KNO 3 solutions on lower molecular weight polymers. Therefore experiments were also conducted in the presence of KNO 3 where it was found that the adsorption was faster and resulted in thicker layers compared to the adsorption from the NaCl solution. This is attributed mainly to the high concentration of K + ions, which are effective binders of the lone pair electrons of the ether groups (–O–) of the PEO and the negatively charged silica on the glass surface.

Neutral polyethylene oxide with a cofactor recommended for particle flocculation

Conventional and neutral high molecular weight polyethylene oxide (PEO) adsorbs on some colloids and fines, flocculating them into flocs. Addition of a cofactor (CF) makes PEO adsorb on all types of colloids and fines, flocculating them into larger flocs. Homoflocculation of fines with PEO alone and with CF added prior to PEO were investigated in this work at low and high effective shear rates. CF role was investigated: it enhanced flocculation amplitude and rate by several magnitudes relative to PEO used alone, and was ascribed to the CF action to stiffen and extend PEO coils. Considering CF-PEO abilities in homoflocculation and in heteroflocculation as recorded in the literature, combination of homo - and heteroflocculation can now be applied to processes. Formed flocs and individual particles will simultaneously deposit onto fibers and, when filtered, particles will be retained in the fiber cake. This technique can be applied in industry processes and water treatment.

Osmotic capsules: A universal oral, controlled-release drug delivery dosage form

An osmotic, oral, controlled-release capsule is described. This capsule provides drug delivery at fixed delivery rates (T 80% = 6 or 14 h) independent of drug properties (e.g., solubility) or drug loading, thereby allowing rapid development of investigational or commercial drugs, especially for proof-of-concept type clinical studies. The capsule body and cap are prepared with cellulose acetate and polyethylene glycol in acetone and water using high density polyethylene molds as templates and a conventional tablet pan coater. After the shells are removed from the molds manually, a laser hole is drilled in the end of the capsule body. The drug is introduced as a shaped tablet admixed with polyethylene oxide. A “push” tablet consisting of high molecular weight polyethylene oxide, microcrystalline cellulose, and sodium chloride is also inserted into the capsule body. The capsule halves lock together due to ridges, alleviating the need for a banding operation.

Morphology and photophysical properties of luminescent electrospun fibers prepared from diblock and triblock polyfluorene-block-Poly(2-vinylpyridine)/PEO blends

We successfully prepared luminescent electrospun (ES) fibers from the polymer blends of diblock poly[2,7-(9,9-dihexylfluorene)]-block-poly(2-vinylpyridine)(di-PFPVP) or triblock P2VP-b-PF-b-P2VP (tri-PFPVP) with polyethylene oxide (PEO) using a single-capillary spinneret. The morphology and photophysical properties of ES fibers were explored via the molecular architecture, solvent selectivity, and different molecular weights of PEO. The ES fibers had diameters around 400–800 nm using solvent of methanol (MeOH)/H2O while those using CHCl3 were around 1–3 μm, which was probably due to the difference on the solvent dielectric constant. Furthermore, the PF aggregated size and emission peak maximum in the ES fibers increased with enhancing the block copolymer composition using CHCl3. However, an insignificant variation was observed using MeOH/H2O. The larger PF aggregated size of the di-PFPVP/PEO blend ES fibers resulted in the red-shifting and broader emission peak, in comparison with that of the tri-PFPVP/PEO blend ES fibers. The efficient interaction of the PEO with the PVP block in two different block copolymers accounted for the above results. In the ES fibers using the low molecular weight of PEO (Mn~100 K), it exhibited a red-shifting on the PL spectra in comparison with the spin-coated films due to the geometrical confinement. Nevertheless, such confinement was probably significantly reduced using the high molecular weight PEO (Mn~2000 K) and thus an insignificant variation was found on the PL spectra. The present study demonstrated that their aggregate morphology and photophysical properties of ES fibers prepared from conjugated rod-coil block copolymer blends could be significantly tuned through polymer architecture, solvent selectivity, and copolymer composition.

Reducing quartz gangue entrainment in sulphide ore flotation by high molecular weight polyethylene oxide

Polyethylene oxide (PEO) was tested to flocculate and depress fine quartz particles in the batch flotation of artificial mixtures of chalcopyrite–quartz as well as a commercial Au–Cu sulphide ore sample. The aggregation/dispersion behaviors of quartz, chalcopyrite and their mixtures in the presence of PEO with and without potassium amyl xanthate (KAX) were studied by photometric dispersion analysis (PDA), scanning electron microscopy (SEM) and zeta potential measurements. Batch flotation results indicated that the addition of low dosages of PEO improved value mineral recovery and concentrate grade during the flotation of both the artificial mixtures of chalcopyrite–quartz and the Au–Cu sulphide ore sample. Aggregation/dispersion test results revealed that the PEO caused non-selective flocculation of quartz and chalcopyrite, forming large hetero-aggregates. However, the addition of KAX caused the chalcopyrite particles to break away from the hetero-aggregates, leading to separate homo-aggregates of quartz and chalcopyrite. The flotation of the fine chalcopyrite and the depression of the fine quartz were thus both improved.

Use of coarse ethylcellulose and PEO in beads produced by extrusion–spheronization

This study evaluated the potential of coarse ethylcellulose (CPEC) and high molecular weight polyethylene oxide (PEO) as excipients in the production of beads by extrusion–spheronization. CPEC was investigated as a diluent and PEO as an extrusion aid and a binder. Beads were manufactured with caffeine as a model drug. Release studies were conducted, and the bead size, shape, yield, and friability were determined. The effects of formulation and process variables and their interactions were studied by a sequential experimental design based on a response surface method. In the initial stage, a two level half fractional factorial design was employed as a screening design, which was subsequently augmented to a central composite design. Statistical analysis indicated that formulation variables including PEO content, microcrystalline cellulose (MCC) content, and water content, and two process variables, namely spheronizer speed and spheronization time, significantly affected the properties of the beads. Interactions between two factors have significant effects on several of the measured responses. Simultaneous optimization of the responses was conducted and validated by performing experiments at the optimal conditions. Overall, the results confirmed that immediate release, spherical beads with low friability and narrow size distribution could be produced with minimal amounts of MCC.

Influence of silica aerogel on the properties of polyethylene oxide-based nanocomposite polymer electrolytes for lithium battery

In this study, a series of nanocomposite polymer electrolytes (NCPEs) with high conductivity and lithium ion transference number, PEO/LiClO 4/SAP, were prepared from high molecular weight polyethylene oxide (PEO), LiClO 4 and low content of homemade silica aerogel powder (SAP), which had higher surface area and pore volume than the conventional silica particle. From the SEM images it was found that the SAP nanoparticles were well dispersed in the PEO polymer electrolyte matrix. The characterization and interactions in the CPEs were studied by DSC, XRD, FT-IR and 7Li NMR analysis. The ac impedance results showed that the ionic conductivity of the CPE was significantly improved by the addition of the as-prepared SAP. The maximum ambient ionic conductivity obtained from the CPE with EO/Li = 6 and 2 wt.% of SAP (O6A2) was about threefold higher than that of the corresponding polymer electrolyte without SAP (O6). In addition, the lithium ion transference number ( t +) of O6A2 at 70 °C was as high as 0.67, which was also three times higher than that of O6 and has not been previously reported for the PEO–LiX-based polymer electrolytes.

Preparation and characterization of composite electrolytes based on PEO(375)-grafted fumed silica

Recent developments in polymer electrolytes have focused on preparation of composites using nano/micron size ceramic particles such as SiO 2, TiO 2, Al 2O 3, BaTiO 3, and MgO. We report here the preparation and characterization of an all-solid state polyethylene oxide (PEO) composite electrolyte from PEO(375)–SiO 2, high molecular weight PEO (MW = 600 K) and LiClO 4 (O/Li = 16/1). Oligomeric PEOs, with ethylene oxide (EO) repeat units 6–9 (<MW> = 375 g/mol), were chemically grafted (~ 30 wt.%) to fumed silica (A380) using a trimethoxy PEO(375)-silane. The surface grafted PEO chains were disordered (no crystallization) and less mobile than the free chains, with the glass transition temperature ( T g) increasing from − 90 °C [PEO(375)-silane] to − 54 °C [PEO(375)–SiO 2]; addition of LiClO 4 (O/Li = 8/1) further raised T g to − 34 °C. Nanocomposite electrolytes with good dimensional stability were obtained by blending 14-wt.% PEO(375)–SiO 2 with semicrystalline PEO(600 K)/LiClO 4 (O/Li = 16/1). Conductivities ( σ) were 10 to 4 times greater [between 10 °C ( σ = 2.1 × 10 − 8 S/cm) and 40 °C ( σ = 1.1 × 10 − 5 S/cm), respectively] than for neat PEO(600 K) or for composite electrolytes having the same amount of native fumed silica, SiO 2. No conductivity improvements were observed above T m or for amorphous PEO(600 K)/LiClO 4 (O/Li = 8/1) with addition of SiO 2 or PEO(375)–SiO 2.