Miscibility Of PEO Research Articles

Morphology and Strength Characteristics of Composites Based on Nanocrystalline Cellulose and Water-Soluble Polymers

The effect of nanocrystalline cellulose (NCC) content on the morphology and strength characteristics of its composites with poly(ethylene oxide) (PEO), polyvinylpyrrolidone (PVP), and their mixture is studied. The miscibility of PEO and PVP improves if NCC is added. Scanning electron microscopy images showed that rearrangement of PEO crystalline regions and sorption of PVP on NCC particles improves the homogeneity of the composite structure and improves the strength characteristics.

Thermal Properties and Intermolecular Interaction of Blends of Poly(ethylene oxide) and Poly(methyl acrylate)

SummaryPolymer blends of poly(ethylene oxide) (PEO) and poly(methyl acrylate) (PMA) were prepared by solution casting method. Thermal stability of the binary PEO/PMA blends was examined by termogravimetric analysis (TGA). Decomposition temperatures of the binary blends were estimated from the onsets of the weight loss curves of TGA thermograms. The decomposition temperatures of the blends increase when the content of PEO elevates. Hence, PEO has a better thermal stability as compared to PMA. The activation energy of thermal decomposition of each sample was calculated from the initial stage of the decomposition. Quantities of EA increase when content of PEO increases in the blends. Differential scanning calorimeter (DSC) was used to investigate the thermal properties of binary PEO/PMA blends. An existence of a single and composition‐dependent glass transition temperature (Tg) for the blends indicates the miscibility of the PEO/PMA blends. The Tgs of PEO/PMA blends increase when PMA content increases. Furthermore, when PMA is blended with PEO, the crystallinity (X*) and melting temperature (Tm) of PEO in PEO/PMA blends are depressed. Thus, the miscibility of the blends in the molten state is in agreement with Tg results. Fourier‐transform infrared (FTIR) spectroscopy was used to study the intermolecular interaction of between PEO and PMA in the blends. The characteristic absorbance bands of ether and carbonyl groups of PEO and PMA were examined by FTIR. PEO and PMA only display weak van der Waals interactions in blends. Hence the miscibility of PEO and PMA in the blends may be more towards the entropic effect instead of the enthalpic effect.

Effects of lithium perchlorate on the nucleation and crystallization of poly(ethylene oxide) and poly(ε-caprolactone) in the poly(ethylene oxide)–poly(ε-caprolactone)–lithium perchlorate ternary blend

The effects of lithium perchlorate (LiClO4) on the nucleation and crystallization of poly(ethylene oxide) (PEO) and poly(ε-caprolactone) (PCL) in the PEO–PCL–LiClO4 ternary blend were studied by using a polarizing optical microscope (POM), differential scanning calorimetry (DSC) and Fourier transformation infrared spectroscopy (FTIR). LiClO4 has a heterogeneous nucleation effect on PEO in the blend, irrespective of the presence of PCL. The coordination interaction between PEO and LiClO4 decreases with the increase of the PCL content, so the heterogeneous nucleation ability of LiClO4 on PEO decreases with the increase of the PCL content in the ternary blends. LiClO4 has no heterogeneous nucleation effect on PCL. In the ternary blend, the heterogeneous nucleation effect of PEO on PCL is remarkably promoted with the addition of LiClO4. POM observations show that the miscibility of PEO and PCL improves after the addition of LiClO4, leading to an increase in the interface volume of PEO and PCL phase domains. The increased concentration-fluctuation at the interface promotes the interfacial nucleation of PCL in the ternary blend. The combination of “fluctuation-assisted crystallization” and “interface-assisted crystallization” mechanisms of the interfacial nucleation of PCL in the PEO–PCL binary blend is also suitable for the interfacial nucleation of PCL in the PEO–PCL–LiClO4 ternary blend.

Understanding the Performance of Melt-Extruded Poly(ethylene oxide)–Bicalutamide Solid Dispersions: Characterisation of Microstructural Properties Using Thermal, Spectroscopic and Drug Release Methods

In this article, we have prepared hot-melt-extruded solid dispersions of bicalutamide (BL) using poly(ethylene oxide) (PEO) as a matrix platform. Prior to preparation, miscibility of PEO and BL was assessed using differential scanning calorimetry (DSC). The onset of BL melting was significantly depressed in the presence of PEO, and using Flory-Huggins (FH) theory, we identified a negative value of -3.4, confirming miscibility. Additionally, using FH lattice theory, we estimated the Gibbs free energy of mixing which was shown to be negative, passing through a minimum at a polymer fraction of 0.55. Using these data, solid dispersions at drug-to-polymer ratios of 1:10, 2:10 and 3:10 were prepared via hot-melt extrusion. Using a combination of DSC, powder X-ray diffractometry and scanning electron microscopy, amorphous dispersions of BL were confirmed at the lower two drug loadings. At the 3:10 BL to PEO ratio, crystalline BL was detected. The percent crystallinity of PEO was reduced by approximately 10% in all formulations following extrusion. The increased amorphous content within PEO following extrusion accommodated amorphous BL at drug to polymer loadings up to 2:10; however, the increased amorphous domains with PEO following extrusion were not sufficient to fully accommodate BL at drug-to-polymer ratios of 3:10.

Study on miscibility of PEO and PCL in blends with PHB by solution viscometry

Viscometric studies were carried out for polymer-blend solutions in chloroform, i.e. for solutions of two polymers in a common solvent. Polymer blends comprised poly(3-hydroxy butyrate) (PHB) in combination with poly(ethylene oxide) (PEO) and poly(ε-caprolactone) (PCL), respectively. Experimental results obey the Huggins equation to an excellent approximation in the concentration range studied. Intrinsic viscosities vary linearly with blend composition to a good approximation. Huggins coefficients display generally nonlinear dependencies on blend composition. Positive deviations from perfect behaviour are attributed to attractions between different chain molecules or miscibility of the constituents. The viscometric study demonstrates that PEO is miscible with PHB, whereas PCL is immiscible.

Poly(ethylene oxide)-polyelectrolyte blends: viscometric and thermal analysis behaviour

The miscibility of binary poly(ethylene oxide) (PEO) and sodium poly(4-styrene sulphonate) (PSS) or [3,6]-ionene (ION) systems, was analysed in aqueous solutions and in the solid state by viscometry and thermal analysis, respectively. Both techniques indicate partial miscibility of PEO–PSS and immiscibility of PEO–ION blends. In water solution, the partial miscibility of the PEO–PSS system is probably due to the counterion Na+ which can partially provide the driving force association in a similar manner to that observed for PEO–surfactant systems. In blend films, the PEO–polyelectrolyte interaction is also analysed in terms of the effect on the PEO crystallization observed through optical microscopy, and the results indicate compatibility between the components in the PEO–PSS system. © 2000 Society of Chemical Industry

Thermodynamics of poly(ethylene oxide) — poly(vinyl acetate) blends

Heat-of-mixing data, obtained on blends of poly(ethylene oxide) (PEO) with whole and fractionated poly(vinyl acetate) (PVAc), were used to feed Patterson's theory of polymer-polymer miscibility. Negative values of mixing enthalpy, contact-energy term, interaction parameter and excess volume were obtained only for blends with the lowest molecular weight PVAc fraction. These results show that miscibility of PVAc with PEO strongly depends on its molecular weight. The calculated unfavourable excess volume term of the Patterson equation is small in comparison with the absolute value of the interaction term. Therefore, miscibility of PEO and low-molecular-weight PVAc is dictated by the weak specific interactions between different repeat units and by the entropic gain in the mixing process.