Preparation and thermal characterization of poly(ethylene oxide)/griseofulvin solid dispersions for biomedical applications

In this work, a series of poly(ethylene oxide)/griseofulvin (PEO/gris) solid dispersions has been prepared and characterized by PLM, FTIR, DSC, and MT‐DSC. It has been found that the crystalline phase morphology depends strongly on the PEO molecular weight and, in the PEO/gris systems, griseofulvin molecules stay in amorphous phase of PEO, which enhances the solubility of a drug and increases its biological access. For PEO‐drug systems containing 5, 10, and 15% gris, FTIR bands due to stretching vibrations of the O? H groups were found at 3436, 3436, and 3413 cm^?1, respectively, whereby for pure PEO 3400, they were located at 3513 cm^?1—the observed shift proves the existence of hydrogen bonds between PEO and griseofulvin. The presence of griseofulvin caused lowering of the systems' melting temperature in the whole concentration range and, as evidenced by MT‐DSC results, recrystallization of PEO in the PEO/griseofulvin systems during melting does occur. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Study on phase change characteristics of PEG/PAM coupling blend

A novel solid–solid phase change materials with polyethylene glycol (PEG) worked as phase change substance and polyacrylamide (PAM) as solid skeleton was synthesized by coupling blend. Their phase change behaviors and structure analysis was studied by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR), they had reversible solid–solid phase change properties. The result indicates that the PEG/PAM PCMs has great transition enthalpy and suitable phase transition temperature in the phase transition process. It can be considered as promising PCMs. Otherwise, their crystallization behavior were analyzed by polarization optical microscopy (POM), the crystalline degrees of these phase change materials were affected due to the intermolecular interaction and chemical bond. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Flow regime transition identification in three phase co‐current bubble columns

Bubble columns have wide applications in absorption, bio‐reactions, catalytic slurry reactions, coal liquefaction; and are simple to operate, have less operating costs; provide good heat and mass transfer. Experiments have been performed for identifying transition regime in a 15 cm diameter bubble column with liquid phase as water and air as the gas phase. Glass beads of mean diameter 35 µm have been used as solid phase. The superficial gas velocity is in the range 0 ≤ U_g ≤ 16.3 cm/s and superficial liquid velocity in the range of 0 ≤ U_l ≤ 12.26 cm/s. Solid loading up to 9% (w/v) has been used. Pressure signals have been measured using differential pressure transducers (DPTs) at four different axial locations. Classical analysis (Wallis approach and Zuber–Findlay approach), Statistical analysis and Fractal analysis have been used for regime transition identification. Statistical analysis and Fractal analysis have shown almost the same transition points for all the liquid and gas velocities. Effect of solid concentration, liquid velocity and gas velocity over transition regime has also been studied. As the solid concentration is increased it has insignificant effect over transition regime for lower values (<1%), while transition values decrease for higher solid concentration (>1%). © 2012 Canadian Society for Chemical Engineering     

Time-resolved conformational analysis of poly(ethylene oxide) during the hydrogelling process

We investigated a drastic conformation change in a poly(ethylene oxide) (PEO) chain during the hydrogelation process using infrared (IR) spectroscopy and quantum chemical calculations (QCCs). Time-resolved in situ IR spectra of the hydrogelling process of a semi-crystalline PEO solid were measured using a flow-through cell. It was found from the time-resolved IR study that gauche conformations around the C-C bonds in the crystalline phase PEO chain maintain their conformations even after hydrogelation, while at least half of the trans conformations around the C-O bonds change into gauche conformations upon hydrogelling. With regard to the phenomena of these conformation changes after contacting water, the destruction and hydrogelation of the crystalline phase around the C-C bonds of the hydrophobic moiety occur prior to changes around the C-O bonds of the hydrophilic moiety. In addition, our QCC confirmed that the stable hydration structure of bridging water, wherein the two hydroxyl groups in a water molecule donate hydrogen bonds to every other ether oxygen atoms in the PEO chain.     

Compatibilizing effects of poly(styrene-graft-ethylene oxide) in blends of polystyrene and butyl acrylate polymers

The compatibilizing effect of poly(styrene-graft-ethylene oxide) in polystyrene (PS) blends with poly(n-butyl acrylate) (PBA) and poly(n-butyl acrylate-co-acrylic acid) (PBAAA) was investigated. No significant effects of the graft copolymer on the domain size were found in the PBA blends. By functionalizing PBA with acrylic acid, the average size of the polyacrylate domains was reduced considerably by the graft copolymer. Thermal and dynamic mechanical analysis of the PS/PBAAA blends revealed that the PBAAA glass transition temperature (T_g) decreased with increasing graft copolymer content. The effect of the graft copolymer in the PS/PBAAA blends can be explained by interactions across the interface due to the formation of hydrogen bonds between the poly(ethylene oxide) (PEO) side chains in the graft copolymer and the acrylic acid segments in the PBAAA phase. Hydrogen bonding was confirmed by IR analysis of binary blends of PEO and PBAAA. Partial miscibility in the PEO/PBAAA blends was indicated by a PEO melting point depression and by a T_g reduction of the PBAAA phase. The thermal properties of the PEO/PBA blends indicated only very limited miscibility. © 1996 John Wiley & Sons, Inc.     

Effect of steric hindrance on hydrogen‐bonding interaction between polyesters and natural polyphenol catechin

The phase behaviors for the blends of poly(3‐hydroxypropionate) (PHP), poly(L ‐lactide) (PLLA), poly(D ‐lactide) (PDLA), and poly(D,L ‐lactide) (PDLLA) with catechin were investigated by differential scanning calorimetry. In PLLA/catechin, PDLA/catechin, and PDLLA/catechin blends, two glass transitions were detected when the catechin content was ≥40 wt %, whereas in PHP/catechin blends only one glass transition was observed over the whole range of blend compositions. The former and the latter results should reflect the inhomogeneous and the homogeneous nature of the blends, respectively, in the amorphous phase. These different phase behaviors should arise from the differences in the chemical structures between PHP and PLLA/PDLA/PDLLA, which dominates the strength and the number of intermolecular hydrogen‐bonding interactions between the ester carbonyl groups of polyesters and the phenol groups of catechin. As detected by FTIR spectroscopy, in comparison with PHP, the steric hindrance of side‐chain methyl groups of PLLA, PDLA, and PDLLA might restrain the formation of hydrogen bonds between their ester carbonyl groups and the phenol hydroxyl groups of catechin, even weakening the strength of such hydrogen bonds. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 91: 3565–3573, 2004     

Influence of technological parameters on the epoxidation of 1‐butene‐3‐ol over titanium silicalite TS‐2 catalyst

BACKGROUND: The influence of technological parameters on the epoxidation of 1‐butene‐3‐ol (1B3O) over titanium silicalite TS‐2 catalyst has been investigated. Epoxidations were carried out using 30%(w/w) hydrogen peroxide at atmospheric pressure. The major product from the epoxidation of B3O was 1,2‐epoxybutane‐3‐ol, with many potential applications. RESULTS: The influence of temperature (20–60 °C), 1B3O/H₂O₂ molar ratio (1:1–5:1), methanol concentration (5–90%(w/w)), TS‐2 catalyst concentration (0.1–6.0%(w/w)) and reaction time (0.5–5.0 h) have been studied. CONCLUSION: The epoxidation process is most effective if conducted at a temperature of 20 °C, 1B3O/H₂O₂ molar ratio 1:1, methanol concentration (used as the solvent) 80%(w/w), catalyst concentration 5%(w/w) and reaction time 5 h. Copyright © 2009 Society of Chemical Industry     

Kraft lignin/poly(ethylene oxide) blends: Effect of lignin structure on miscibility and hydrogen bonding

Blends of poly(ethylene oxide) (PEO) with softwood kraft lignin (SKL) were prepared by thermal blending. The miscibility behavior and hydrogen bonding of the blends were investigated by differential scanning calorimetry (DSC) and Fourier transform infrared (FTIR) spectroscopy. The experimental results indicate that PEO was miscible with SKL, as shown by the existence of a single glass‐transition temperature over the entire composition range by DSC. In addition, a negative polymer–polymer interaction energy density was calculated on the basis of the melting point depression of PEO. The formation of strong intermolecular hydrogen bonding was detected by FTIR analysis. A comparison of the results obtained for the SKL/PEO blend system with those previously observed for a hardwood kraft lignin/PEO system revealed the existence of stronger hydrogen bonding within the SKL/PEO blends but weaker overall intermolecular interactions between components; this suggested that more than just hydrogen bonding was involved in the determination of the blend behavior in the kraft lignin/PEO blends. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 1437–1444, 2005     

Hydrogen bonding effect on the poly(ethylene oxide), phenolic resin,and lithium perchlorate–based solid‐state electrolyte

The interaction behavior of solid‐state polymer electrolytes composed of poly(ethylene oxide) (PEO)/novolac‐type phenolic resin and lithium perchlorate (LiClO₄) was investigated in detail by DSC, FTIR, ac impedance, DEA, solid‐state NMR, and TGA. The hydrogen bonding between the hydroxyl group of phenolic and ether oxygen of the PEO results in higher basicity of the PEO. The higher basicity of the ether group can dissolve the lithium salts more easily and results in a greater fraction of “free” anions and thus higher ionic conductivity. DEA results demonstrated that addition of the phenolic increases the dielectric constant because of the partially negative charge on the ether group induced by the hydrogen bonding interaction between ether oxygen and the hydroxyl group. The study showed that the blend of PEO(100)/LiClO₄(25)/phenolic(15) possesses the highest ionic conductivity (1.5 × 10^?5 S cm^?1) with dimensional stability. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1207–1216, 2004     

Stretchable gas barrier films achieved by hydrogen-bond self-assembly of nano-brick multilayers

Inorganic–organic hybrid films containing two-dimensional nanosheets have shown good gas barrier performance, but moderate tensile property, because of the rigid characteristics of covalent or ionic bonds between the assembly units. In this work, we used LDH nanosheets rich in hydroxyl groups as building units, followed by modification of tannic acid (TA), to assemble with polyethylene oxide (PEO) through hydrogen bonds. Compared with previous work, the tensile property and oxygen barrier performance of (TA@LDH/PEO)_n films have been significantly improved. A 50-bilayer TA@LDH/PEO film, deposited on a 1 mm thick natural rubber substrate, results in a 29× reduction (contrast with bare substrate) in oxygen transmission rate and maintains its good barrier property even under a large elongation of 120%. The excellent tensile and gas barrier properties are attributed to the ductility of hydrogen bond network among building blocks and the significant prolongation of oxygen transmission path induced by LDH nanosheets.     

PEO-PPO-PEO嵌段共聚物温敏特性及其影响机制的分子模拟

以Pluronic P85为例,采用全原子分子动力学模拟方法研究了单链嵌段类共聚物PEO-PPO-PEO在不同溶剂中的温敏性相转变行为及其影响机制。分子模拟结果显示当Pluronic P85溶解在水溶液和极性有机溶剂（甲醇）中时,升温导致PPO和PEO与水或甲醇分子间氢键断裂、使得溶剂化壳层被破坏而释放出水或甲醇分子,Pluronic P85发生构象塌缩,呈现反向温度响应特性。当Pluronic P85溶解在非极性有机溶剂（甲苯）中时,升温导致分子热运动加剧而削弱Pluronic P85链分子内相互作用,使其在甲苯中的构象更加舒展,呈现正向温敏特性。分子模拟结果还展现了PEO和PPO链段的溶剂化效应随温度的变化及其对于聚合物构象的影响,对于此类聚合物的分子设计和应用提供了理论依据。     

Nanocomposite solid polymer electrolytes based on polyethylene oxide,modified nanoclay,and tetraethylammonium tetrafluoroborate for application in solid‐state supercapacitor

Nanocomposite solid polymer electrolytes (SPEs) have been prepared from polyethylene oxide (PEO), organically modified nanoclay (MNclay), and tetraethylammonium tetrafluoroborate (TEABF₄) salt. The concentration of the salt has been varied in the respective SPE, wherein PEO/MNclay ratio was kept constant. It has been proposed that three types of complex formation could be operative in the SPEs due to the interactions among PEO, MNclay, and the salt. The complex formation mechanism has been postulated on the basis of X‐ray diffraction (XRD) analysis, transmission electron microscopic (TEM) observation, differential scanning calorimetric (DSC) analysis, and polarized optical microscopic (POM) observation. ‘Complex 1’ and ‘complex 3’ formation could be involved in the crystalline phase as indicated by DSC and XRD analyses, whereas ‘complex 2’ formation might be restricted in the amorphous phase as suggested by TEM observation. The ionic conductivity of the SPEs has been correlated with the results obtained from XRD, DSC, and POM analyses. The formation of complex 1 and complex 2 could be responsible for the increase in the ionic conductivity, whereas complex 3 formation might decrease the ionic conductivity. An activated carbon‐based supercapacitor has been fabricated using SPEs and characterized by cyclic voltammetry, galvanostatic ‘charge–discharge’ behavior, and impedance spectroscopic analysis. POLYM. ENG. SCI., 55:1536–1545, 2015. © 2015 Society of Plastics Engineers     

Blends of poly(ethylene oxide) with chitosane acetate salt and with dibuturylchitin: Structure and morphology

Summary This paper presents the results of a study of the chemical structure and morphology of polyblends of chemically modified chitin and chitosane with poly(ethylene oxide). Poly(ethylene oxide)(PEO) forms a compatible one-phase blend with chitosane acetate salt (PEO/CHIACA) and a non-compatible two phase blend with dibutyrylchitin (PEO/DBCHI). The compatible one-phase blend of PEO/CHIACA is formed due to the formation of strong hydrogen bonds between ether groups in PEO and hydroxy groups in CHIACA. Chemical and crystalline morphological structure is discussed here.     

Synthesis and properties of amphiphilic copolymers of butyl acrylate and methyl methacrylate with uniform polyoxyethylene grafts

Amphiphilic copolymers of butyl acrylate (BA) and methyl methacrylate (MMA) with uniform polyoxyethylene (PEO) grafts were synthesized by the copolymerization of BA and MMA with a methacrylate‐terminated PEO macromer in benzene with azobisisobutyronitrile as an initiator. The effects of various copolymerization conditions on the grafting efficiency and molecular weight of the copolymers, as well as the effect of the copolymerization time on the conversions of the macromer and the monomers, were reported. The copolymers, with uniform PEO grafts, were purified by successive extractions with water and ether/acetone (3/7) to remove unreacted macromer and ungrafted copolymers of MMA and BA, respectively. The purified graft copolymers were characterized with IR, ¹H‐NMR, membrane osmometry, gel permeation chromatography, and differential scanning calorimetry. The highest grafting efficiency was about 90%, and molecular weight of the copolymers varied around 10⁵. The average grafting number of the copolymer was about 10. A study of the crystalline properties, emulsifying properties, phase‐transfer catalytic ability, and mechanical properties of the graft copolymers showed that the emulsifying volume decreased with the increasing molecular weight of the PEO grafts but increased with the PEO content. The conversion of potassium phenolate in the Williamson solid–liquid reaction obviously increased with an increasing PEO content of the graft copolymers. The crystallinity of the graft copolymers increased with the PEO content of the graft copolymers or the molecular weight of the macromer used. The copolymers, prepared under certain conditions, behaved as thermoplastic elastomers. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2982–2988, 2003     

Multi-Phase Composite Nanofibers via Electrospinning of Latex Containing Nanocapsules with Core-Shell Morphology

Nanocapsules containing hexadecane (HD) as core material and polystyrene (PS) as shell, were electrospun with polyethylene oxide (PEO) as a matrix material into the fiber webs. The morphology and thermal properties of PEO fibers containing (1) both PS nanocapsules with core-shell morphology and solid PS particles, (2) only solid PS particles, and (3) without any PS particles, were compared and the effect of PEO concentration on morphology of the resultant fibers have been studied. The resultant fibers were characterized by means of Transmission Electron Microscopy (TEM), Differential Scanning Calorimetry (DSC), and Thermogravimetric Analysis (TGA). Both TEM observation and DSC analyses confirmed that the PS nanocapsules were encapsulated within the PEO nanofibers. The fibers had an average diameter of 950 nm for nanocapsules containing parts, 300 nm for solid particles containing parts, and 150 nm for usual parts. The phase change temperatures and phase transition heat of the produced fibers were determined by DSC analyses. TGA was also used to confirm the preparation of multi phase fibers and to determine the amount of HD within the fibers.     

New Lead‐free (1−x)BaTiO3–xBi(Mg1/2Zr1/2)O3 Solid Solution with Morphotropic Phase Boundary and Diffuse Phase Transition

A new lead‐free perovskite solid solution (1?x)BaTiO₃–xBi(Mg_1/2Zr_1/2)O₃ with morphotropic phase boundary (MPB) has been developed, and its structural and dielectric properties have been investigated. Rietveld structural analysis of the X‐ray diffraction data suggest a composition‐dependent tetragonal (P4mm) to cubic () phase transition with an intermediate, phase coexistence region, demarcating the MPB. The compositions with x ≤ 0.05 are tetragonal in the P4mm space group and the compositions with x ≥ 0.25 are cubic in the space group. Coexistence of monoclinic phase (space group Cm) with tetragonal/cubic phase (space group P4mm/) is observed in the MPB region for the compositions with 0.10 ≤ x ≤ 0.22. The temperature dependence of permittivity exhibits a nonrelaxor type diffuse phase transition for all the compositions across the MPB.     

Study of electrospinning of sodium alginate,blended solutions of sodium alginate/poly(vinyl alcohol) and sodium alginate/poly(ethylene oxide)

Alginate is an interesting natural biopolymer for many of its merits and good biological properties. This paper investigates the electrospinning of sodium alginate (NaAlg), NaAlg/PVA‐ and NaAlg/PEO‐ blended systems. It was found in this research that although NaAlg can easily be dissolved in water, the aqueous NaAlg solution could not be electrospun into ultrafine nanofibers. To overcome the poor electrospinnability of NaAlg solution, synthetic polymers such as PEO and PVA solutions were blended with NaAlg solution to improve its spinnability. The SEM images of electrospun nanofibers showed that the alginate (2%, w/v)–PVA (8%, w/v) blended system in the volume ratio of 70 : 30 and the alginate (2%, w/v)–PEO (8% w/v) blended system in the volume ratio of 50 : 50 could be electrospun into finest and uniform nanofibers with average diameters of 118.3 nm (diameter distribution, 75.8–204 nm) and 99.1 nm (diameter distribution, 71–122 nm), respectively. Rheological studies showed a strong dependence of spinnability and fiber morphology on solution viscosity and thus on the alginate‐to‐synthetic polymer (PVA or PEO) blend ratios. FTIR studies indicate that there are the hydrogen bonding interactions due to the ether oxygen of PEO (or the hydroxyl groups of PVA) and the hydroxyl groups of NaAlg. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Effect of polyethylene oxide–polyethylene glycol content and humidity on performance of electro‐active paper actuators based on cellulose/polyethylene oxide–polyethylene glycol microcomposite

The effect of humidity and polyethylene oxide (PEO)–polyethylene glycol (PEG) content on the actuator performance of cellulose/PEO–PEG microcomposites was studied. Upon blending 5% PEO–PEG, the maximum bending displacement of the actuator increased nearly twice compared to that of cellulose EAPap actuator. However, further increase of PEO–PEG content resulted in decreased actuator performance. This might be due to the increased intermolecular interaction by hydrogen bonding that reduces the mobility of the molecules. The actuator performance test showed that the increase in humidity level rather reduced the maximum displacement of the actuators. X‐ray diffractogram and Fourier transform infrared spectrum analysis suggested a structural change of the microcomposites as well as disruption of cellulose/PEO–PEG association attributed to the actuator performance degradation at high humidity level. POLYM. ENG. SCI., 2010. © 2010 Society of Plastics Engineers     

Effects of amorphous silica nanoparticles and polymer blend compositions on the structural,thermal and dielectric properties of PEO–PMMA blend based polymer nanocomposites

The polymer nanocomposite (PNC) films consisted of poly(ethylene oxide) (PEO) and poly(methyl methacrylate) (PMMA) blend matrices dispersed with nanoparticles of amorphous silica (SiO₂) have been prepared by solution-cast method followed by melt-press technique. Effects of SiO₂ concentration (x?=?0, 1, 3 and 5 wt%) and PEO–PMMA blend compositional ratios (PEO:PMMA?=?75:25, 50:50, and 25:75 wt%) on the surface morphology, crystalline phase, polymer-polymer and polymer-nanoparticle interactions, melting phase transition temperature, dielectric permittivity, electrical conductivity, electric modulus and the impedance properties of the PNC films have been investigated. The crystalline phase of the PNC films decreases with the increase of PMMA contents which also vary anomalously with the increase of SiO₂ concentration in the films. The melting phase transition temperature and polymer-nanoparticle interactions significantly change with the variation in the compositional ratio of the blend polymers in the PNC films. It is observed that the effect of SiO₂ on the dielectric and electrical properties of these PNCs vary greatly with change in the compositional ratio of PEO and PMMA in the blends. The dielectric relaxation process of these films confirm that the polymers cooperative chain segmental dynamics becomes significantly slow when merely 1 wt% SiO₂ nanoparticles are dispersed in the polymer blend matrix.     

蒙脱土对热塑性淀粉结晶和力学性能的影响

用熔融挤出方法制备的甘油塑化热塑性淀粉(GTPS)/蒙脱土(MMT)复合材料,可以有效抑制GTPS长时间放置的结晶行为,提高其力学性能。不同相对湿度下复合材料、GTPS、淀粉的X ray衍射说明,MMT对GTPS结晶有抑制作用;力学测试表明,随着w(MMT)=0%提高到30%,复合材料最大应力达到27 31MPa,应变从85 3%下降到17 8%,杨氏模量达到206 7MPa,断裂能从1 921N·m下降到1 723N·m。红外(FTIR)谱图显示复合材料中淀粉分子的碳氧(C—O)基团向高波数移动,蒙脱土中可反应性羟基(OH)向低波数移动。这表明蒙脱土分子可反应OH和淀粉分子OH之间有氢键形成,使GTPS中淀粉分子之间氢键难以形成,蒙脱土在复合材料中起到阻隔剂的作用,是抑制GTPS结晶的主要原因;扫描电子显微镜(SEM)显示,蒙脱土均匀分散在GTPS中,提高了材料力学性能。