Increase Of PEO Content Research Articles

Carbon nanotube‐polybutadiene‐poly(ethylene oxide)‐based composite fibers: Role of cryogenic treatment on intrinsic properties

AbstractThe low‐temperature response and the notion of crystallization kinetics are critical for developing elastomeric composite fibers, thus the crystallization and mechanical properties are essential for the application of composites of polybutadiene at low temperatures. Despite the high amount of fiber joining and entanglement due to polymers' low glass transition, a defect‐free micro‐scale electrospun carbon nanotube (CNT)‐containing poly(ethylene oxide) (PEO) and polybutadiene (PBu) composite elastomeric fibers with uniform fiber diameter and distribution are successfully fabricated. Thermomechanical behavior analyzed via frequency‐dependent dynamic mechanical analysis under cryogenic conditions shows a remarkable increase in decomposition temperatures (Tend) and storage and loss modulus at cryogenic temperatures, particularly when small amounts of CNTs are present. Dynamic mechanical treatment from 120 K to elevated temperatures yields a pronounced logarithmic increase in Tend by an increase of PEO content (from BEC1 to BEC4) compared to the treatment from 300 K. Through X‐ray diffraction, large shifts toward larger 2θ and formation of new crystals are observed, particularly for the BEC4 sample with high PEO content. Nanoparticles after cryo‐treatment linked with crystallinity are registered by ultra‐high resolution scanning electron microscopy. Improving the thermal and mechanical properties is critical in developing high‐performance composite fibers for cryogenic engineering applications, especially for future research to facilitate them in aerospace and low‐temperature medical and surgical treatments.

3D-printed PLA/PEO blend as biodegradable substrate coating with CoCl2 for colorimetric humidity detection

This study aimed to fabricate biodegradable substrate with colorimetric humidity indicator for detective moisture in food packaging. The poor properties of poly(lactic acid) (PLA) were enhanced by melt blending PLA with non-toxic poly(ethylene oxide) PEO at 180 °C. Specifically, three-dimensional (3D) substrates of PLA/PEO blends were fabricated by solvent-cast 3D printing. Furthermore, cobalt chloride (CoCl2) solution was printed onto the substrate with an inkjet printer to serve as a colorimetric humidity sensing indicator. It found that the flexibility and thermal stability of the PLA were improved and the hydrophilicity was increased with an increase in PEO content. Color changes and the sensitivity of this material were confirmed using image analysis and total color difference. The CoCl2 indicator displayed color changes that ranged from blue to pink under ambient conditions (above 60%RH), revealing suitable potential for frozen food packaging material with aim to detect amount of moisture in the packaging.

Experimental design to evaluate properties of electrospun fibers of zein/poly (ethylene oxide) for biomaterial applications

AbstractThe production of polymer fibers from the combination of zein and PEO might have great potential in the field of biomaterial. Zein/PEO fibers were obtained in this work through solution electrospinning. An experimental design, 24‐1, was used for evaluating the influences of PEO content in the blend, distance from the needle tip to the collector, applied electric voltage and solution flow for average fiber diameter and relative‐yield process. Beyond this, the relationship between PEO content in the blend and the fiber properties were evaluated through FTIR, DSC, TG, tensile tests, and cytotoxic tests. The factor that exerts the greatest effect on the average fiber diameter response was the electrical voltage. The increase in PEO content in the blend decreased the thermal stability and increased the degree of the fibers' crystallinity. The mechanical tests showed that fibers with higher elongation were obtained at richer PEO blends. The fibers presented cytocompatible characteristics.

Morphological study of cellulosic hydrogel nanofiber for biomedical application

In this work, water-insoluble and biocompatible hydrogel nanoweb was prepared via electrospinning. Sodium carboxymethyl cellulose (CMCNa), the cellulose derivative with water solubility and biocompatibility, was electrospun with help of building polymer, poly(ethylene oxide) (PEO). After removal of PEO, the CMCNa in the nanoweb was ionically crosslinked by FeCl3. The viscosity of the mixed solution was decreased with the increase of PEO content mainly due to the smaller molecular size of PEO comparing to CMCNa. The reduced interaction resulted from small molecular size decreased the viscosity with the increase of PEO content. The PEO also improved the spinnability of the solution by screening repulsive force between the CMCNa molecules. As a result, the increase of PEO content resulted in the decreases of the viscosity and the fiber diameter simultaneously. After extraction of PEO, the diameter was significantly reduced. The surface of the nanowebs became bumpy after crosslinking and fiber diameter increased with the increase of crosslinking time. The chemical structure changes of the nanowebs during the process were analyzed by FT-IR spectra. The cytotoxicity of the nanoweb was also assessed using MTT assay. Furthermore, the drug release behaviors of the nanowebs were evaluated using UV–Vis spectrometer. The nanoweb with increased fiber diameter showed more sustained release behavior because of its low specific surface area.

Preparation of Pure and Stable Chitosan Nanofibers by Electrospinning in the Presence of Poly(ethylene oxide).

Electrospinning was employed to obtain chitosan nanofibers from blends of chitosans (CS) and poly(ethylene oxide) (PEO). Blends of chitosan (MW (weight-average molecular weight) = 102 kg/mol) and PEO (M (molecular weight) = 1000 kg/mol) were selected to optimize the electrospinning process parameters. The PEO powder was solubilized into chitosan solution at different weight ratios in 0.5 M acetic acid. The physicochemical changes of the nanofibers were determined by scanning electron microscopy (SEM), swelling capacity, and nuclear magnetic resonance (NMR) spectroscopy. For stabilization, the produced nanofibers were neutralized with K2CO3 in water or 70% ethanol/30% water as solvent. Subsequently, repeated washings with pure water were performed to extract PEO, potassium acetate and carbonate salts formed in the course of chitosan nanofiber purification. The increase of PEO content in the blend from 20 to 40 w% exhibited bead-free fibers with average diameters 85 ± 19 and 147 ± 28 nm, respectively. Their NMR analysis proved that PEO and the salts were nearly completely removed from the nanostructure of chitosan, demonstrating that the adopted strategy is successful for producing pure chitosan nanofibers. In addition, the nanofibers obtained after neutralization in ethanol-aqueous solution has better structural stability, at least for six months in aqueous solutions (phosphate buffer (PBS) or water).

PEO를 이용한 Alg-Na 바인더의 물성향상

There has been increasing demand to the eco-friendly materials such as phytoncide which is extracted to plants in the textile industry, recently. It is interesting that alginic acid sodium salt(Alg-Na) is used to eco-friendly binder for the functional capsule finishing. In this study, we made PEO/Alg-Na blend solutions of various ratio and observed the changing binding property of the blend solutions according to PEO contents through FT-IR, DSC, contact angle, peel strength, etc. The viscosity of Alg-Na/PEO blend solutions increased with increase of contents and the viscosity quickly increased with increase of PEO content in Alg-Na 5% content, specially. It is shown that the hydrogen bond peak by blend of Alg-Na and PEO found through FT-IR analysis but the peak decreased in PEO above 60% content. And the peel strength was predominant in PEO 50% ratio.

Gas diffusivity, solubility and permeability in polysulfone–poly(ethylene oxide) random copolymer membranes

In this study polysulfone–poly(ethylene oxide) (PSF–PEO) random copolymers were synthesized using a polycondensation reaction via nucleophilic substitution. The PSF–PEO random copolymer membranes were prepared by varying PEO content in a glassy PSF matrix to see the effects of PEO segments on the change of gas transport properties. The PEO content varied from 5 mol% (9 wt.%) to 20 mol% (31 wt.%). The gas diffusivity, solubility and permeability of light gases (e.g., He, H 2, O 2, N 2, CO 2 and CH 4) in these random copolymer membranes were measured as a function of PEO content in PSF, and discussed in relation to the changes in gas transport behavior, including physical and structural properties. Originally we expected that the incorporation of amorphous, flexible PEO segments in a stiff, glassy polymer such as PSF would lead to an increase in gas permeabilities, particularly CO 2 permeability because PEO segments with polar ether oxygen units is known to have good affinity with CO 2 molecules, thereby resulting in high level of CO 2 sorption. However, all gas permeabilities, including CO 2 permeability, were unexpectedly reduced with the increase of PEO content (∼31 wt.%) and the permselectivities of gas pairs of interest (e.g., CO 2/H 2, CO 2/N 2 and CO 2/CH 4) were not as high as we anticipated. PSF–PEO random copolymers synthesized in this study do not have well-phase separated structures, that is, each component can be compatible in this copolymer system, leading to no distinct large PEO domains in the PSF–PEO copolymer membranes. As a result, the effect of PEO domains on the gas permeation properties in the PSF–PEO copolymer membranes might be relatively small.

Copolymer of poly(4-vinylpyridine)- g-poly(ethylene oxide) respond sharply to temperature, pH and ionic strength

The stimuli-responsive copolymers with poly(ethylene oxide) (PEO) as side chain were prepared by free-radical copolymerization of methacrylamide end-capped PEO macromonomer and 4-vinylpyridine (4VP). Phase transition behavior of these copolymers of poly(4-vinylpyridine)- g-poly(ethylene oxide) (P4VP- g-PEO) was investigated as a function of polymer concentration, temperature, pH and ionic strength by monitoring the turbidity of the polymer solutions. The copolymers displayed sharp response to temperature and pH. The LCST of P4VP- g-PEO copolymer increased with the increase of PEO content and decreased with increasing pH due to the deprotonation of the pyridine ring, indicating well-tunable LCST. In addition, the LCST of P4VP- g-PEO9 presented a unique phase transition behavior with varying salt concentration, showing a minimum with 1 M NaCl solution at pH 6.0.

Structure and Drug Release in a Crosslinked Poly(Ethylene Oxide) Hydrogel

Hydrogels are a continuously expanding class of pharmaceutical polymers designed for sustained or controlled drug release. The structure and intermolecular interactions in such systems define their macroscopic properties. The aim of this study was to investigate the mechanism of swelling, drug impregnation, and drug release from poly(ethylene oxide) (PEO) gel crosslinked by urethane bonds. A combination of SAXS/WAXS/SANS techniques enabled us to determine the phase transition between lamellar and extended gel network, and to apply different descriptions of crystallinity, based on lamellar and crystal lattice structures. It is shown that even low (1-7% w/w) loading of model drugs acetaminophen and caffeine, produced significant disorder in the polymer matrix. This effect was particularly pronounced for acetaminophen due to its specific ability to form complexes with PEO. The drug-release profiles were analyzed using a general cubic equation, proposed for this work, which allowed us to determine the gel hydration velocity. The results indicate that the release profiles correlate inversely with the polymer crystallinity.

Characterization and properties of amphiphilic block polymer based on poly(ethylene oxide) and poly(butyl acrylate)

AbstractPEO‐b‐PBA [PEO: poly(ethylene oxide); PBA: poly(butyl acrylate)], an amphiphilic block copolymer, prepared by redox radical polymerization, was characterized by infrared and 1H nuclear magnetic resonance spectroscopy. The result revealed the existence of PEO and PBA segment in purified block copolymer. The thermal behavior of the block copolymer was determined by differential scanning calorimetry. With the introduction of PBA noncrystalline segment, the crystallinity of PEO was decreased. The emulsifying and water absorptive properties of PEO‐b‐PBA were also examined. It was found that the emulsifying volume and type were dependent on the amount of block copolymer and the PEO content in block copolymer. Under a certain range, the emulsifying volume increases with an increase of PEO content. The more the PEO content in block copolymer, the stronger the water absorptivity was. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 3432–3436, 2003

Crystallization induced microstructure of polymer blends consisting of two crystalline constituents

The crystallization kinetics and semicrystalline morphology of a polymer blend consisting of two crystalline components, poly(ethylene oxide) (PEO) and poly(ethylene succinate) (PES), have been investigated. PEO and PES were miscible in the melt. Slight dilution with PEO (wPEO≤0.2) promoted the crystallization kinetics of PES because of enhanced segmental mobility upon blending. Further increase in PEO content reduced the PES crystallization rate owing to the dominant effect of depression in crystallization driving force. The semicrystalline morphology of PEO/PES blends was probed by small-angle X-ray scattering (SAXS). At temperatures between the melting point of PEO (TmPEO≈59°C) and that of PES (TmPES≈101°C), the blend was a crystalline/amorphous system. Both crystallizations via direct cooling to 70°C (where only PES crystallized) and direct cooling to 40°C (where two components crystallized simultaneously) followed by heating to 68°C (to melt PEO crystals) created a high extent of interfibrillar segregation coupled with a minor extent of interlamellar incorporation of amorphous PEO. At temperatures below TmPEO, where the blend was a crystalline/crystalline system, direct cooling to 40°C (one-step crystallization) generated two separate lamellar stack (LS) domains: one containing almost pure PES lamellae and the other consisting of mixed PEO and PES lamellae. Crystallization at 70°C followed by cooling to room temperature (two-step crystallization) also yielded two separate LS domains, due to the crystallization of PEO within the interfibrillar regions.

Relaxation Studies in PEO/PMMA Blends

To study the influence of PEO on the relaxation process of PMMA, the real and imaginary parts of the permittivity, ε‘ and ε‘ ‘, of PEO/PMMA blends (with PEO contents up to 25 wt %) were measured as a function of frequency and temperature, and the results obtained were compared with those of pure PMMA. It is shown that the presence of PEO broadens the relaxation process of PMMA and increases its relaxation strength. The lower Tg component (PEO) has a plasticizing effect on the relaxation of PMMA, for the blends with 10 and 15% PEO. The splitting of the αβ process of PMMA seems to be affected by the presence of the second component, being the onset of the α relaxation shifted to lower temperatures with the increase of PEO concentration. The DSC thermograms show a single glass transition temperature, which is displaced to lower temperatures with the increase of PEO content, and no evidence of crystallinity was found. The presence of a singular broad transition in the 20% PEO blend, evidenced in both dielectric and calorimetric experiments, may be associated with the merging of the α and β process and to concentration fluctuations, confirming that this blend lies in the border of the miscibility/immiscibility region.

Hydrophilic polyurethaneurea membranes: influence of soft block composition on the water vapor permeation rates

High molecular weight segmented polyurethaneurea (PUU) copolymers based on an aliphatic diisocyanate, bis(4-isocyanatocyclohexyl)methane and mixed hydrophilic and hydrophobic soft segments were prepared. Hydrophilic blocks consisted of poly(ethyleneoxide) (PEO) of molecular weight 1450 g/mol, whereas the hydrophobic blocks were poly(tetramethylene oxide) of molecular weight 2000 g/mol. Ethylene diamine was used as the chain extender. Hard segment contents of the copolymers were kept constant at 18%, whereas PEO contents were varied between 0% and 50% by weight. Water vapor permeation rates (WVPR) of thin films (23–178 μm) cast from dimethylformamide solutions were determined. In studies performed at 23°C and 50% relative humidity, the relationship between PEO content and WVPR followed an S-shaped curve. For copolymers containing up to about 15% by weight of PEO, WVPR were fairly low. This was followed by a region where WVPR increased continuously for membranes containing between 15% and 30% PEO. Further increase in PEO content above 30% did not influence the WVPR substantially. There was also a dramatic increase in WVPR with an increase in temperature from 23°C to 37°C. Activation energy of permeation was determined to be 91.5 kJ for PUU containing 22.0% by weight of PEO. Equilibrium water absorption levels of PUU containing different levels of PEO in their backbone structures followed a similar trend to that of WVPR. Hydrophilic PUUs showed good tensile properties and mechanical integrity even at very high levels of water absorption.

In vivo biocompatibility study of ABA triblock copolymers consisting of poly(L‐lactic‐co‐glycolic acid) A blocks attached to central poly(oxyethylene) B blocks

Films of three ABA-block copolymers composed of lactic-co-glycolic acid A blocks and poly(oxyethylene) (PEO) B blocks and one random lactic-co-glycolic acid copolymer (PLG) were studied to investigate the influence of different polymer compositions and molecular weights on the tissue reaction, appearance of toxic degradation products, and swelling behavior in the cage implant system in rats. The inflammatory tissue reaction was followed over a 21-day implantation period by monitoring the leukocyte concentration, the extracellular acid, and alkaline phosphatase activities in a quantitative manner. Size and density of adherent macrophages and foreign body giant cells on the film surfaces were determined. The ABA and PLG implants caused only a minimal inflammatory reaction, as characterized by a low concentration of leukocytes during the implantation period when compared to empty cage controls. The content of PEO had an influence on the density of the adherent cells on the surface of the polymer film. An increase in PEO content and molecular weight decreased the cellular density during the implantation period. As demonstrated by scanning electron microscopy, no degradation was observed for all polymers during the implantation period. Our results demonstrate that the ABA block copolymers and PLG copolymer are equally well tolerated in the cage implant test system. © 1996 John Wiley & Sons, Inc.

In vivo biocompatibility study of ABA triblock copolymers consisting of poly(L-lactic-co-glycolic acid) A blocks attached to central poly(oxyethylene) B blocks

Films of three ABA-block copolymers composed of lactic-co-glycolic acid A blocks and poly(oxyethylene) (PEO) B blocks and one random lactic-co-glycolic acid copolymer (PLG) were studied to investigate the influence of different polymer compositions and molecular weights on the tissue reaction, appearance of toxic degradation products, and swelling behavior in the cage implant system in rats. The inflammatory tissue reaction was followed over a 21-day implantation period by monitoring the leukocyte concentration, the extracellular acid, and alkaline phosphatase activities in a quantitative manner. Size and density of adherent macrophages and foreign body giant cells on the film surfaces were determined. The ABA and PLG implants caused only a minimal inflammatory reaction, as characterized by a low concentration of leukocytes during the implantation period when compared to empty cage controls. The content of PEO had an influence on the density of the adherent cells on the surface of the polymer film. An increase in PEO content and molecular weight decreased the cellular density during the implantation period. As demonstrated by scanning electron microscopy, no degradation was observed for all polymers during the implantation period. Our results demonstrate that the ABA block copolymers and PLG copolymer, are equally well tolerated in the cage implant test system.

Pervaporation of organic liquid mixtures through poly (ether imide) segmented copolymer membranes

Poly (ether imide) segmented copolymers were prepared from polyether diamine and comonomer diamine with acid anhydride. They had microphase-separated structure consisting of microdomains of rubbery polyether segments and of glassy polyimide segments. Pervaporation (PV) of benzene-cyclohexane, benzene- n-hexane and acetone-cyclohexane mixtures through membranes of the copolymers were investigated. As to polyether segment, poly (ethylene oxide) (PEO) gave much better membrane performance than poly (propylene oxide) and poly (tetrahydrofuran). With an increase in PEO content, [PE], the specific permeation flux, Ql, increased significantly and the separation factor, α, decreased. Sorption and permeation occurred in microdomains of polyether segments, whereas microdomains of polyimide segments contributed to suppression of swelling of polyether microdomains and to film-forming ability. The membranes were preferentially permeable to benzene or acetone over cyclohexane or n-hexane due to preferential sorption and diffusion of benzene or acetone. The block length of the PEO segment, n, affected the membrane performance; lower Ql and higher α were obtained for shorter block length. A typical membrane with [PE] = 41 wt% and n = 9 displayed Ql = 2 kg μm/ (m 2h) and α = 9 at a feed composition of 60 wt% benzene in cyclohexane and Ql = 8 kg μm/ (m 2h) and α = 17 at a feed composition of 68 wt% acetone in cyclohexane at 323 K. Argon plasma treatment was effective for enhancement of the selectivity without significant reduction in Ql, especially for the acetone-cyclohexane system.

Infrared Dichroism Study of Segmented Polyurethaneurea with Triblock Polyether Soft Segments

Infrared (IR) dichroism study of segmented polyurethaneurea (SEUU) with ABA type triblock copolymer as a soft segment was carried out, where A stands for poly(oxyethylene) (PEO) and B stands for poly(oxytetramethylene) (PTMO). IR dichroism analysis of SEUU films under elongation suggested that the introduction of PEO units to the ends of PTMO brought about more aggregation of the hard segments, i.e., the better microphase separation in SEUU than segmented polyurethaneurea (SPUU) prepared from PTMO. Under uniaxial extension, the crystalline hard segment domain oriented transverse to the stretch direction at early stage, the degree of orientation being larger with the increase of PEO content. The larger was the PEO content, the better the microphase separation in SEUU.