Molecular Weight Poly Ethylene Oxide Research Articles

Design, Fabrication, and Wearable Medical Application of a High‐Resolution Flexible Capacitive Temperature Sensor Based on the Thermotropic Phase Transition Composites of PEO/PVDF‐HFP/H3PO4

AbstractPhase transition materials have the potential to be utilized as high‐resolution temperature‐sensitive materials. However, it is a challenge to develop them into temperature sensors with good stability and repeatability. In this work, inspired by phase transition theory and the electrical double‐layer capacitance principle, a novel high‐resolution flexible capacitive temperature sensor based on Polyethylene oxide(PEO)/Poly(vinylidene fluoride‐co‐hexafluoropropylene)/H3PO4 is proposed for the first time. By blending high and low molecular weight PEO and adding ionic solution, the proposed sensor exhibits high resolution (0.05 °C) and response speed (<12 s) within 35–43 °C. The novel introduction of a mesh structure aids the material in achieving microdomain control of PEO crystallization and improves the repeatability (Ex < 2.2%) of the sensor. The sensor is used for monitoring human body temperature and diabetic foot ulcers, and the results show that the sensor can achieve continuous and comfortable body temperature monitoring and early‐stage diabetic foot ulcer diagnosis, offering broad applications in health monitoring and rehabilitation medicine.

Flexible Electrolyte Sheets Using Sulfonated Cellulose Nanofiberfor Sheet-Type All-Solid-State Batteries

With the rapid spread of electric vehicles that do not use fossil fuels for suppression of global warming, all-solid-state batteries (ASSBs) have been studied as a next-generation battery to improve the cruising range and safety. In general, ASSBs use solid-state electrolyte such as polymer or inorganic electrolytes instead of organic electrolyte solutions, which prevent from electrolyte leakage and its degradation especially at high temperatures. Therefore, it is possible to simplify for the cell design and to increase the energy density. However, for the practical use relatively high interface resistance between electrode and solid-state electrolyte is one of the critical problems. Recently, addition of cellulose nanofiber (CNF) into polyethylene oxide (PEO) electrolyte was reported to improve flexibility and mechanical strength. Also, this method can reduce the interface resistance and improve the cycle performance [1]. In this study, we prepared new composite electrolyte membranes by using sulfonated CNF (S-CNF, Yokokawa Bio Frontia Inc.), together with a low molecular weight PEO, i.e. tetraglyme (G4), and some amounts of ceramic powders to support the ionic conductivity and mechanical strength. The electrochemical properties were investigated by using SUS | SUS and Li | Li symmetric cells to elucidate the mechanism of ionic transport. Mixtures of S-CNF, Lithium-Ion Conducting Glass-Ceramics (LiCGCTM, OHARA) or SiO2 powders, Lithium Bis(trifluoromethanesulfonyl) imide (LiTFSI) salt and G4 solvent were prepared in a predetermined ratio. The resulting solutions were coated onto PET film and dried in vacuum to form membranes, and then peeled off to obtain the S-CNF composite electrolyte membranes. The ion conductivity was measured by AC impedance method at a frequency range from 1 MHz to 100 mHz and applied voltage of ±50 mV by using a SUS | SUS symmetric cell. The interface resistances were evaluated by using a Li | Li symmetric cell to subject to a Li dissolution/ deposition test at 25°C. The tests was conducted in a constant current mode with a voltage range of -2.0 to 2.0 V, a current density of 0.50 mA cm- 2 and a capacity limit of 0.50 mAh cm-2. Fig. 1 shows Nyquist plots of a LICGC pellet and the S-CNF composite membranes containing LiCGC or SiO2 powder. The composite membranes has no semicircular component different from the LICGC pellt. This indicates that the interface resistance between the electrolyte menbranes and Li metal is drastically reduced owing to the flexibility. Also, both case of S-CNF composite menbrane exhibited almost same plots. This indicates that the contribution for ionic conductivity by the LICGC solid-state electrolyte is smaller than that by the polymer electrolyte conponent of LiTFSI/G4. In fact, the ion conductivity calclated from the Nyquist plots were 55.0 and 51.7 μS cm-1 for the S-CNF composite menbranes containing LICGC and SiO2 powder, respectively. These values were five times higher than that of pure LICGC pellet (9.53 μS cm-1). On the other hand, Li |Li symmetric cell test exhibited a quite stable polarization curves for the both S-CNF menbranes remaining the overpotential below 5 mV for up to 200 cycles. This also indicates the good chemical stability against Li metal. The mechanism of ionic conductivity, the role of S-CNF in the composite menbranes and the mechanical strength will be totally discussed in the meeting.

Optimizing the Performance of NMC 622 Battery Half Coin Cells by Using Amphiphilic Aqueous Binders to Modulate the Percolation of Carbon Black

N-methyl-2-pyrrolidone (NMP) is the conventional solvent for processing high-nickel cathodes as it dissolves the polymer binder polyvinylidene fluoride (PVDF) and does not leach nickel from the cathode material. NMP is restricted under REACH1 regulations as a ‘substance of very high concern’. Aqueous processing with hydrophilic polymer binders is an emerging alternative to the NMP/PVDF solvent/binder system. Aqueous processed cathodes offer advantages over conventional processing with NMP, namely nontoxic, unrestricted use and cost-effectiveness being 100 times less expensive than NMP/PVDF. However, carbon black is hydrophobic so it does not disperse in water. One way around this problem is to substitute the binder for one that is water-soluble so it can bind to and disperse the carbon black.Aqueous binders have generally yielded unimpressive battery performance, therefore a novel binder system has been studied. In this work, an amphiphilic polymer (pluronic F68) was used to control the dispersion of carbon black in the slurry, and a high molecular weight polyethylene oxide (PEO) was used as a viscosity modifier. Measuring steady-state viscosity flow curves and oscillatory strain measurements, a narrow viscosity range in which carbon black percolates in the cathode slurry was identified, and validated by conductivity data. Working within this range of viscosities, a series of formulations were developed that maximize the mass fraction of active material whilst ensuring enough binder is present to disperse the carbon black in water. The PEO to pluronic ratio was varied for each formulation. Slurries are optically opaque and difficult to characterize, so zeta potential measurements were taken to assess the degree of carbon-black dispersion in the slurry and QCMD to quantify the density. The ratio of active material (NMC 622) to carbon black to polymer was 95:3:2 respectively. Ultimately, the formulations presented were of a constant viscosity, attained by controlling the solids loading of the slurries. Half-coin cells were cycled at charge and discharge rates of 1C, using a voltage range of 3.0 to 4.3 V.An optimal ratio of 25% PEO to 75% pluronic-F68 was identified; these half-coin cells achieved a mean 1st specific discharge capacity of 147 mAhg-1 with capacity retention averaging 86%. Through adsorption measurements, it was found that the affinity between the binder and carbon black seems to correlate with the size of carbon black flocs that form, enabling the tuning of the percolation of carbon black in the slurry. By carefully controlling the viscosity, it was shown that electrochemical cell performance correlates very strongly with both the PEO to pluronic ratio and the slurry conductivity for this system, as seen in Fig.1. This data, along with adsorption and zeta-potential measurements indicate that the affinity of the polymer binder to carbon black can affect the electrochemical performance of the cell.References Regulation (EC) No 1907/2006 of the European Parliament and of the Council concerning the Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH) 2019, Article 57. Figure 1

Composite Separators with Very High Garnet Content for Solid‐State Batteries

AbstractLithium‐metal solid‐state batteries are attractive as next generation of Li‐ion batteries due to higher safety and potentially higher energy density. To improve processability, solid‐composite separators combine advantages of inorganic and polymer separators in hybrid structure. We report a systematic approach to fabricate composite separators with high content (90–95 wt %) of ceramic Li‐ion conducting Li6.45Al0.05La3Zr1.6Ta0.4O12 (LLZO) powder embedded in a polyethylene oxide (PEO)‐LiTFSI (20 : 1) matrix and understand factors affecting their properties and performance. Separators with good mechanical flexibility and excellent thermal stability were obtained, by optimizing materials and processing parameters. It was found that PEO molecular weight strongly influences the microstructure and electrochemical properties of the separators. In optimized separator with 90 wt % of LLZO and PEO with Mw 300,000 g/mol, a total ionic conductivity of 1.4×10−5 S/cm at 60 °C was achieved. The ceramic‐rich separator showed excellent long‐term cycling stability for more than 460 cycles (1000 h) at 0.1 mA/cm2 in Li/Li symmetrical cells and achieved a critical current density of 0.25 mA/cm2. The separators also enabled initial discharge capacities of more than 160 mAh/g in full cells with Li metal anode and composite solid‐state LiNi0.6Co0.2Mn0.2O2 cathode, although rapid capacity fade was observed after 10 cycles in fully solid‐state configuration.

On the rheological properties of Silica – Poly(ethylene-oxide) dispersions: "Shake-gels" II The effect of silica concentration and molecular weight of polymer

Using rheological techniques, the effect of silica concentration and polyethylene oxide molecular weight has been investigated to follow the gelation/shear thickening behaviour of PEO silica water mixtures, a phenomenon which has become known as "shake gels”. By monitoring the viscosity as a function of the shear rate it was observed that at a critical shear rate the viscosity increased by many orders of magnitude. The higher the silica concentration and the higher the polymer molecular weight the lower the shear rate required for the gel to form. Once formed by dropping the shear rate to a low value or by monitoring the viscoelastic moduli the relaxation of the gel back into the liquid state could be followed. It was noted that the lower the polymer molecular weight or the lower the silica concentration the faster the relaxation process was. It is postulated that the silica particles effectively cross link the gel so that the more silica particles per polymer molecule would result in slower relaxation. Conversely in the gel formation stage the more silica particles per polymer the faster the gel forms are a consequence of the ease by which the silica particles can cross link to form the gel.

Covalently attached phosphonic acid‐Si2O3‐PEO polymer membranes for PEMFC applications

AbstractIn the context of growing interest in phosphonic acid proton exchange membranes (PEMs) for fuel cell applications, we report on new PEMs containing low‐cost polyethylene oxide (PEO) covalently linked by siloxane bonds, SiOSi, to phosphonic acid (PA). Key chemistry in the formation of these membranes involves hydrolysis and condensation reactions of triethoxysilyl propyl capped PEO and pre‐hydrolyzed dimethyl phosphonatoethyltrimethoxysilane (DMPTMS) giving PEO‐Si2O3‐PA and cross‐linked chain PEO‐Si2O3‐PEO organosilsesquioxane components. The Si2O3 can enhance membrane thermal and mechanical properties. The membrane formulations were varied by (a) reagent ratios (b) PEO molecular weights or using polypropylene oxide (PPO) (c) incorporating chain extending groups methylene diphenyl diisocyanate (MDI) or hexamethylene diisocyanate (HDI). These variations provided five membrane families, one of which afforded a complete group of robust membranes with weight% x of PA, PAx in range PA0–PA33. These were studied using ATR‐FTIR, dry membrane water uptake capacity, ion exchange capacity (IEC), and conductivity from room temperature to 120°C at 100% relative humidity. Conductivity increased with PAx reaching 15 mS cm−1 at 120°C, activation energy 0.1 eV, for membrane PA33 for which thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and energy dispersive X‐ray analysis (EDAX) are reported. A comparative performance of the five membrane families is presented.

Physical-Entanglements-Supported Polymeric Form Stable Phase Change Materials with Ultrahigh Melting Enthalpy.

With the rapid development of new energy and the upgrading of electronic devices, structurally stable phase change materials (PCMs) have attracted widespread attentions from both academia and industries. Traditional cross-linking, composites, or microencapsulation methods for preparation of form stable PCMs usually sacrifice part of the phase change enthalpy and recyclability. Based on the basic polymer viscoelasticity and crystallization theories, here, a kind of novel recyclable polymeric PCM is developed by simple solution mixing ultrahigh molecular weight of polyethylene oxide (UHMWPEO) with its chemical identical oligomer polyethylene glycol (PEG). Rheological and leakage-proof experiments confirm that, even containing 90% of phase change fraction PEG oligomers, long-term of structure stability of PCMs can be achieved when the molecular weight of UHMWPEO is higher than 7000kg mol-1 due to their ultralong terminal relaxation time and large number of entanglements per chain. Furthermore, because of the reduced overall entanglement concentration, phase change enthalpy of PCMs can be greatly promoted, even reaching to ≈185 J g-1, which is larger than any PEG-based form stable PCMs in literatures. This work provides a new strategy and mechanism for designing physical-entanglements-supported form stable PCMs with ultrahigh phase change enthalpies.

In vitro test methods for evaluating high molecular weight polyethylene oxide polymer induced hemolytic and thrombotic potential

To combat opioid abuse, the U.S. Food and Drug Administration (FDA) released a comprehensive action plan to address opioid addiction, abuse, and overdose that included increasing the prevalence of abuse-deterrent formulations (ADFs) in opioid tablets. Polyethylene oxide (PEO) has been widely used as an excipient to deter abuse via nasal insufflation. However, changes in abuse patterns have led to unexpected shifts in abuse from the nasal route to intravenous injection. Case reports identify adverse effects similar to thrombotic thrombocytopenic purpura (TTP) syndrome following the intravenous (IV) abuse of opioids containing PEO excipient. Increased risk of IV opioid ADF abuse compared to clinical benefit of the drug led to the removal of one opioid product from the market in 2017. Because many generic drugs containing PEO are still in development, there is interest in assessing safety consistent with generic drug regulation and unintended uses. Currently, there are no guidelines or in vitro assessment tools to characterize the safety of PEO excipients taken via intravenous injection. To create a more robust excipient safety evaluation tool and to study the mechanistic basis of HMW PEO-induced TMA, a dynamic in vitro test system involving blood flow through a needle model has been developed.

Oral fast-dissolving risperidone loaded electrospun nanofiber drug delivery systems for antipsychotic therapy

Risperidone is an antipsychotic drug classified as BCS Class II with low solubility at physiological pH and orally used in the treatment of schizophrenia. Electrospinning is one of the newest fabrication methods used for the development of fast soluble drug delivery systems. In this study, an orally disintegrating film (ODF) formulation of risperidone was developed with green electrospinning technique. Different molecular weight polyethylene oxide (PEO) as a polymer and xylitol or Kollidon VA64 as a disintegration agent were used for the preparation of formulations. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR) analyses were conducted as part of pre-formulation studies to identify possible incompatibilities in formulation components. We characterized ODFs based on their mechanical properties, shape and diameter of nanofibers, disintegration behavior, and in vitro dissolution profiles. A few wrinkles appeared on the surface of fibers prepared with xylitol, but a smooth surface was evident on Kollidon VA64 fibers. Disintegration studies performed in the simulated oral environment showed that ODFs disintegrate in as little as 1 s. The dissolution behavior of developed ODFs and commercial products was compared with a dissolution study in distilled water. The chosen formulations had acceptable mechanical properties with much faster dissolution compared to the commercially available product. In this study, risperidone ODF formulation was successfully produced and characterized. The study showed that risperidone-loaded nanofibers could provide a promising alternative to conventional oral dosage forms like tablets and capsules.

Measurement and control of extensional viscosity in barrier coating dispersions

This study aimed to understand the effect of various rheological additives on the extensional viscosity of barrier coating dispersions, as well as to understand the role extensional viscosity plays in stabilizing a liquid curtain. The apparent extensional viscosity was measured using two devices that create accelerating flows: a capillary viscometer and an orifice rheometer. Additives tested include several polyvinyl alcohols, a high molecular weight polyethylene oxide, and carboxymethylcellulose. Extensional viscosity plays a significant role in stabilizing a liquid curtain, as it slows down hole expansion and prevents impurities and disturbances from causing holes in the first place. Some of the additives could substantially increase the extensional viscosity of the dispersions without increasing the shear viscosity outside the typical range of processability for a curtain coater. Some of the additives exhibited coil-stretch transition, meaning they start increasing extensional viscosity above a certain extension rate. Polymers with low chain lengths exhibited finite extensibility, which indicates the polymer chain has fully extended and cannot provide further extensional viscosity, even though the extending force is increased. Polymeric additives with stiff or branched chains significantly raised shear viscosity without increasing extensional viscosity. Both methods could reliably measure extensional viscosity in curtain coating barrier dispersions.

Crystallization in blend of polycaprolactone and high molecular weight polyethylene oxide

The concentration distribution in blend of polyethylene oxide (PEO)/polycaprolactone (PCL) and subsequent crystallization were investigated with differential scanning calorimetry, in-situ small angle X-ray scattering and wide angle X-ray scattering. By using PEOs with a molecular weight of 1 × 106 g/mol (PEO1M) and 1 × 105 g/mol (PEO100k), respectively, it is revealed that in initial blend the concentration of PEO1M in PEO-rich region is higher than that determined by miscibility. This non-equilibrium distribution induced by crystallization is maintained after melting, since slow relaxation of PEO1M hinders the redistribution process. Crystallization behavior of blend with 25 % of PEO1M at different melting temperatures was further investigated. The crystallinity shows no dependence on melting temperature, while the long period of PEO1M decreases continuously when melting temperature exceeds 140 °C. This decrease indicates more PCL chains diffuse into PEO-rich regions with increasing temperature and molten PCL chains reduce the entanglement number of PEO1M as solvent. Moreover, the periodicity of PEO1M lamellae becomes worse when crystallization proceeds faster, which is related to slower exclusion of PCL chains.

Bio-Resorption Control of Magnesium Alloy AZ31 Coated with High and Low Molecular Weight Polyethylene Oxide (PEO) Hydrogels.

Magnesium AZ31 alloy has been chosen as bio-resorbable temporary prosthetic implants to investigate the degradation processes in a simulating body fluid (SBF) of the bare metal and the ones coated with low and high-molecular-weight PEO hydrogels. Hydrogel coatings are proposed to control the bioresorption rate of AZ31 alloy. The alloy was preliminary hydrothermally treated to form a magnesium hydroxide layer. 2 mm discs were used in bioresorption tests. Scanning electron microscopy was used to characterize the surface morphology of the hydrothermally treated and PEO-coated magnesium alloy surfaces. The variation of pH and the mass of Mg2+ ions present in the SBF corroding medium have been monitored for 15 days. Corrosion current densities (Icorr) and corrosion potentials (Ecorr) were evaluated from potentiodynamic polarisation tests on the samples exposed to the SBF solution. Kinetics of cumulative Mg ions mass released in the corroding solution have been evaluated regarding cations diffusion and mass transport parameters. The initial corrosion rates for the H- and L-Mw PEO-coated specimens were similar (0.95 ± 0.12 and 1.82 ± 0.52 mg/cm2day, respectively) and almost 4 to 5 times slower than that of the uncoated system (6.08 mg/cm2day). Results showed that the highly swollen PEO hydrogel coatings may extend into the bulk solution, protecting the coated metal and efficiently controlling the degradation rate of magnesium alloys. These findings focus more research effort on investigating such systems as tunable bioresorbable prosthetic materials providing idoneous environments to support cells and bone tissue repair.

Single-step generation of double emulsions in aqueous two-phase systems

This communication presents a simple yet straightforward method for preparing water-in-water-in-water particle-stabilized double emulsions, also known as Pickering double emulsions. The approach involves using oppositely charged nanoparticles (OCNPs) in two distinct fluid phases, promoting self-assembly and the formation of aggregates with varying sizes and compositions. By enhancing the interfacial area through the adsorption of aggregates at the interface, this method increases the Gibbs detachment energy of particles between the two aqueous phases, forming stable double emulsions. Furthermore, we investigated the impact of the molecular weight of polyethylene oxide and dextran in the respective fluid phases and the mass ratio (M) of the OCNPs on double emulsion formation. The results demonstrate that the molecular weight of the polymers used in the aqueous phase is a critical parameter influencing the structural formation of the emulsion and the generation of double emulsions. Consequently, double emulsions are formed when equal molecular weight polymer mixtures are employed at an appropriate M, with the dispersed phase placed in the highly viscous continuous phase. The proposed method offers a one-step synthesis process, enabling easy preparation, and exhibits excellent stability for at least 30 days. This study represents the first reported approach for the one-step synthesis of multiple emulsions in an aqueous two-phase system utilizing a Pickering emulsion template.

Continuous Monitoring of the Hydration Behavior of Hydrophilic Matrix Tablets Using Time-Domain NMR.

Time-domain NMR (TD-NMR) was used for continuous monitoring of the hydration behavior of hydrophilic matrix tablets. The model matrix tablets comprised high molecular weight polyethylene oxide (PEO), hydroxypropyl methylcellulose (HPMC), and polyethylene glycol (PEG). The model tablets were immersed in water. Their T2 relaxation curves were acquired by TD-NMR with solid-echo sequence. A curve-fitting analysis was conducted on the acquired T2 relaxation curves to identify the NMR signals corresponding to the nongelated core remaining in the samples. The amount of nongelated core was estimated from the NMR signal intensity. The estimated values were consistent with the experiment measurement values. Next, the model tablets immersed in water were monitored continuously using TD-NMR. The difference in hydration behaviors of the HPMC and PEO matrix tablets was then characterized fully. The nongelated core of the HPMC matrix tablets disappeared more slowly than that of the PEO matrix tablets. The behavior of HPMC was significantly affected by the PEG content in the tablets. It is suggested that the TD-NMR method has potential to be utilized to evaluate the gel layer properties, upon replacement of the immersion medium: purified (nondeuterated) water is replaced with heavy (deuterated) water. Finally, drug-containing matrix tablets were tested. Diltiazem hydrochloride (a highly water-soluble drug) was employed for this experiment. Reasonable in vitro drug dissolution profiles, which were in accordance with the results from TD-NMR experiments, were observed. We concluded that TD-NMR is a powerful tool to evaluate the hydration properties of hydrophilic matrix tablets.

Effect of green synthesis bimetallic Ag@SiO2 core–shell nanoparticles on absorption behavior and electrical properties of PVA-PEO nanocomposites for optoelectronic applications

A green and easy technique was used to synthesize silver and silica (Ag@SiO2) core–shell nanoparticles (NPs) in the matrix blend polymers matrix. Core–shell nanoparticles were loaded into polyvinyl alcohol (PVA) and ultrahigh molecular weight polyethylene oxide (UHMW-PEO) blended polymer to fabricate new nanocomposite films (NCFs) using the developed solution-sonication-casting technique. The spectroscopic properties of the resultant films were investigated using x-ray diffraction (XRD), Fourier transforms infrared (FTIR), visible light microscope (OLM), field emission scanning electron microscope (FESEM), FESEM-energy dispersive spectroscope (FESM-EDX), UV/visible spectrometer, and LCR meter to investigate the structural, morphological, optical, and electrical characteristics. XRD revealed the presence of the semi-crystalline nature of PVA-UHMWPEO/ Ag@SiO2 NCFs. The degree of crystallinity increased after embedding. The NPs were well distributed within the NCFs according to OLM and SEM, and FESM-EDX confirmed the presence of C, O, Si, and Ag elements. FTIR spectrum observed strong bonding after the loading of NPs, and other peaks were hidden. The UV/visible spectrums suggested an absorption at ~ 210 nm. Based on the Tauc plot model, the optical bandgap (Eg) values decreased from 5.52 eV to 4.57 eV. The electrical conductivity values were significantly increased with the increasing frequency and (Ag@SiO2) core–shell nanoparticles (NPs) loading ratio. The PVA-UHMWPEO/Ag@SiO2 NCFs explained enhanced lattice strain. The obtained NCFs are suitable for use in various optoelectronic and nanodevice applications.

Determining critical overlap concentration of polyethylene oxide to support excipient safety assessment of opioid products

Intravenous administration of abuse-deterrent opioid products poses high safety risks, in part due to the presence of high molecular weight polymeric excipients. Previous in vivo studies in animal models have shown that the higher molecular weight (Mw) polymeric excipients like polyethylene oxide (PEO) were directly linked to such adverse responses as intravenous hemolysis and kidney damage. PEO polymers have been widely used in abuse-deterrent formulations (ADF) of opioid products, adding to concerns over the general safety of the opioid category due to the unknown safety risk from abuse via unintended routes. The current study focused on the determination of the critical overlap concentration (c*) at various PEO molecular weights to aid in explaining differences in observed adverse responses from previous animal studies on the intravenous administration of PEO solutions. Adverse in vivo responses may be related to the viscoelastic regime of the polymer solution, which depends not only on Mw but also on concentration. Having a localized polymer concentration in the blood above the c*, i.e., the transition from the dilute to semi-dilute entangled viscoelastic regime, may influence the flow behavior and interactions of cells in the blood. The relationship of c* to this combination of physical, chemical, and rheological effects is a possible driving force behind adverse in vivo responses.

Crystallization and phase separation in PEDOT:PSS/PEO blend thin films: Influence on mechanical and electrical properties at the nanoscale

Thin films of polymeric blends composed of poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) and polyethylene oxide (PEO) were investigated by varying the concentration of the two components over the entire range of compositions and the molecular weight of PEO. Phase separation and crystallization have been studied at different length scales by combining Atomic Force Microscopy (AFM) and Grazing Incidence Wide Angle X-ray Scattering (GIWAXS) using synchrotron light. Several different arrangements in the thin films of the two polymers constituting the blend were observed and discussed in detail, providing information about their reciprocal influence at the micro- and nano-scale. In addition to that, we were able to estimate quantitative nanomechanical and nanoelectrical properties via AFM and finally revealing the dependence of the thin films' physical properties on their composition and structure. By varying the blend composition, we achieved different coating capability, mechanical properties, and electrical conductivity. Furthermore, depending on the PEO molecular weight, the electrical response of the resulting blends’ thin films shows some differences. In the low range concentration, the blend thin films with high molecular weight PEO present coarser conducting paths than in those with the low molecular weight counterparts. For intermediate concentrations, a more effective phase segregation of PEDOT:PSS and PEO is achieved for high molecular weight PEO. These differences are also translated to different electrical conductivity.

Cytotoxicity evaluation of poly(ethylene) oxide nanofibre in MCF-7 breast cancer cell line

Biocompatible polymers have received significant interest from researchers for their potential in diagnostic applications. This type of polymer can perform with an appropriate host response or carrier for a specific purpose. The current study aims to fabricate and characterise poly(ethylene) oxide (PEO) nanofibres with different concentrations for cytotoxicity evaluation in human breast cancer cell lines (MCF-7) and to get an optimal PEO nanofibre concentration (permissible limit) as a suitable polymer matrix or carrier with potential use in diagnostic applications. The fabrication of PEO nanofibres was done using electrospinning and was characterised by structure and morphology, surface roughness, chemical bonding and release profiles. The functional effects of PEO nanofibres were evaluated with MTS assay and colony formation assay in MCF-7 cells. The results showed that viscosity plays a vital role in synthesising a polymer solution in electrospinning for producing beadless nanofibrous mats ranging from 4.7 Pa·s to 77.7 Pa·s. As the PEO concentration increases, the nanofibre diameter and thickness will increase, but the surface roughness will be decreased. The average fibre diameter for 5 wt% PEO, 6 wt% PEO and 7 wt% PEO nanofibres were 129 ± 70 nm, 185 ± 55 nm and 192 ± 53 nm, respectively. In addition, the fibre thickness for 4 wt% PEO, 5 wt% PEO, 6 wt% PEO and 7 wt% PEO nanofibres were 269 ± 3 μm, 664 ± 4 μm, 758 ± 7 μm and 1329 ± 44 μm, respectively. Contrarily, the surface roughness for 4 wt% PEO, 5 wt% PEO, 6 wt% PEO and 7 wt% PEO nanofibres were 55.6 ± 9 nm, 42.8 ± 6 nm, 42.7 ± 7 nm and 36.6 ± 1 nm, respectively. PEO nanofibres showed the same burst release pattern and rate due to the same molecular weight of PEO with a stable release rate profile after 15 min. It also demonstrates that the percentage of PEO nanofibre release increased with the increasing PEO concentration due to the fibre diameter and thickness. The findings showed that all PEO nanofibres formulations were non-toxic to MCF-7 cells. It is suggested that 5 wt% PEO nanofibre exhibited non-cytotoxic characteristics by maintaining the cell viability from dose 0–1000 μg/ml and did not induce the number of colonies. Therefore, 5 wt% PEO nanofibre is the optimal nanofibre concentration and was suggested as a suitable base polymer matrix or carrier with potential use for diagnostic purposes. The findings in this study have demonstrated the influence of cell growth and viability, including the effects of PEO nanofibre formulations on cancer progress characteristics to achieve a permissible PEO nanofibre concentration limit that can be a benchmark in medical applications, particularly diagnostic applications.

Nanoporous MgAl<sub>2</sub>O<sub>4</sub> coating on porous Al<sub>2</sub>O<sub>3</sub> support by aerosol deposition method for organic polymer filtration membrane

Ultra- and nanofiltrations are utilized for the separation of polymers and proteins. In this study, we have investigated the application of the MgAl2O4 membrane produced by the aerosol deposition (AD) method for the separation of a polymer. A MgAl2O4 ultrafiltration membrane on the porous Al2O3 support layer was produced with intentionally leaving nano-sized pores instead of a completely dense membrane. The filtration performance was investigated by removing 1 million molecular-weight polyethylene oxide (PEO) from water, and the rejection rate with the AD MgAl2O4 on Al2O3 support to PEO was ∼44 % at the differential pressure of only ∼0.1 MPa, which was three times higher than our previous report by the dip-coating MgAl2O4 on Al2O3 of ∼14 %.

Evaporation-controlled dripping-onto-substrate (DoS) extensional rheology of viscoelastic polymer solutions

Extensional flow properties of polymer solutions in volatile solvents govern many industrially-relevant coating processes, but existing instrumentation lacks the environment necessary to control evaporation. To mitigate evaporation during dripping-onto-substrate (DoS) extensional rheology measurements, we developed a chamber to enclose the sample in an environment saturated with solvent vapor. We validated the evaporation-controlled DoS device by measuring a model high molecular weight polyethylene oxide (PEO) in various organic solvents both inside and outside of the chamber. Evaporation substantially increased the extensional relaxation time lambda _{E} for PEO in volatile solvents like dichloromethane and chloroform. PEO/chloroform solutions displayed an over 20-fold increase in lambda _{E} due to the formation of an evaporation-induced surface film; evaporation studies confirmed surface features and skin formation reminiscent of buckling instabilities commonly observed in drying polymer solutions. Finally, the relaxation times of semi-dilute PEO/chloroform solutions were measured with environmental control, where lambda _{E} scaled with concentration by the exponent m=0.62. These measurements validate the evaporation-controlled DoS environment, and confirm that chloroform is a good solvent for PEO, with a Flory exponent of nu =0.54. Our results are the first to control evaporation during DoS extensional rheology, and provide guidelines establishing when environmental control is necessary to obtain accurate rheological parameters.