Stability constants and thermodynamic parameters of some intermacromolecular complexes of acrylic copolymers and poly(vinyl pyrrolidone)

Stability constants and thermodynamic parameters (e.g. ΔH⁰ and Δ⁰) have been determined for intermacromolecular complexes of methacrylic acid-methacrylamide and acrylic acid-acrylamide copolymers with poly(vinyl pyrrolidone) (PVP). The presence of nonionic units in the copolymers greatly enhances the stability of the complexes with PVP. The enthalpy and entropy changes of the systems with temperature have been interpreted in terms of various modes of interaction between the components.     

Effect of various types of interaction on the stability of some ternary interpolymer complexes involving poly(ethylene imine), poly(acrylic acid) and poly(ethylene glycol)

The effect of various types of interaction on the stability of multi‐component interpolymer complexes was studied for some three‐component interpolymer complexes involving poly(ethylene imine), poly(acrylic acid) and poly(ethylene glycol). The degree of linkage (θ), stability constant (K) and related thermodynamic parameters (e.g. ΔH⁰ and ΔS⁰) of these complexes were determined at several temperatures and compared for various complexation systems. The comparative study indicated considerable difference in the values of these parameters, which is explained in terms of various modes of interaction between the components. Copyright © 2010 Society of Chemical Industry     

Thermal behavior of poly(acrylic acid)–poly(vinyl pyrrolidone) and poly(acrylic acid)–metal–poly(vinyl pyrrolidone) complexes

Thermal analysis (TGA and DTA) of samples of PAA, PVP, PAA–PVP complexes, containing different weight fractions of PAA and ternary polymer–metal–polymer complexes, were studied. The activation energy parameters for the thermal degradation were also calculated. The study of the effect of FeCl₃, NiCl₂, and Ni(NO₃)₂ on the TGA and DTA curves of the complexes showed that the decompositions are dependent on the concentrations and the nature of the metal ions. The DTA traces of PAA–PVP complex containing FeCl₃, NiCl₂, and Ni(NO₃)₂ showed that the treatment of the complex with these metal ions causes considerable changes in the thermal decomposition of PAA–PVP complex. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 4049–4057, 2006     

A study of blending and complexation of poly(acrylic acid)/poly(vinyl pyrrolidone)

Poly(acrylic acid) (PAA) and poly(vinyl pyrrolidone) (PVP) were chosen to prepare polymer complex and blends. The complex was prepared from ethanol solution and the blends were prepared from 1-methyl-2-pyrrolidone solution. DSC results show that the T_gs of the PAA/PVP blends lie between those of the two constituent polymers, whereas T_g of the PAA/PVP complex is higher than both blends and the two constituent polymers. TGA results show that degradation temperature, T_d, of PAA increases upon adding PVP in the blend, but thermal stability of the complex is higher than that of the blends as reflected by the higher T_d. Both FTIR and high-resolution solid state NMR show strong hydrogen bonding between PAA and PVP by showing significant chemical shift. The T_1ρ(H) measurement shows that the homogeneity scale for the blend is at ∼20 Å and that for the complex is ∼15 Å.     

Transient currents in poly(vinyl alcohol)–poly(vinyl pyrrolidone) polymer blend films

Transient currents (charging and discharging currents) in poly(vinyl alcohol) (PVA)–poly(vinyl pyrrolidone) (PVP) polymer blend films were measured over the temperature range 30–150°C at field strengths of 2.32–23.2 × 10⁶ Vm^?1. Polymer films were prepared by the isothermal immersion technique. Activation energies were evaluated from quasi-steady-state currents. A single relaxation peak was observed both from isochronal currents and low frequency dielectric relaxation. Activation energies evaluated from these two methods are found to be in fairly good agreement. The polarization is considered to be due to space charge origin along with some contribution from dipolar groups. The maximum loss was observed in Sample I (PVA: PVP = 25:75), suggesting maximum heterogeneity in this blend ratio.     

Influence of solvent on the poly (acrylic acid)-oligo-(ethylene glycol) polymer gel electrolyte and the performance of quasi-solid-state dye-sensitized solar cells

The influence of solvents on the property of poly (acrylic acid)-oligo-(ethylene glycol) polymer gel electrolyte and photovoltaic performance of quasi-solid-state dye-sensitized solar cells (DSSCs) were investigated. Solvents or mixed solvents with large donor number enhance the liquid electrolyte absorbency, which further influences the ionic conductivity of polymer gel electrolyte. A polymer gel electrolyte with ionic conductivity of 4.45 mS cm⁻¹ was obtained by using poly (acrylic acid)-oligo-(ethylene glycol) as polymer matrix, and absorbing 30 vol.% N-methyl pyrrolidone and 70 vol.% γ-butyrolactone with 0.5 M NaI and 0.05 M I₂. By using this polymer gel electrolyte coupling with 0.4 M pyridine additive, a quasi-solid-state dye-sensitized solar cell with conversion efficiency of 4.74% was obtained under irradiation of 100 mW cm⁻² (AM 1.5).     

Characterization of polymeric biocomposite based on poly(vinyl alcohol) and poly(vinyl pyrrolidone)

Biocompatible and easily available materials from dairy production waste were used for modification of water‐soluble polymeric blends of Poly(vinyl alcohol) (PVA) and Poly(vinyl pyrrolidone) (PVP). The resulting biocomposites of PVA/PVP with various concentrations of lactose (L) or calcium lactate (CL) (0, 5, 15, 25, 35 wt%) were prepared by using a solvent cast technique and then characterized by optical microscopy, tensile test, water content determination, differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy equipped by attenuated total reflectance device, and also tested for biodegradability. The films were transparent with a smooth surface. The results confirm that L and CL work as fillers in polymeric matrix. The tensile investigations showed enhanced Young's modulus (E) and tensile strength for low‐filled of composite materials (up to 5 wt% L and 15 wt% CL). The biodegradation test in aquatic conditions revealed improved biodegradability of modified blends. Both L and CL seem to be suitable for the modification of polymers, which can be convenient from economical and environmental point of view. POLYM. COMPOS., 27:147–152, 2006. © 2006 Society of Plastics Engineers.     

Biocompatible polymer blends: Effects of physical processing on the molecular interaction of poly(vinyl alcohol) and poly(vinyl pyrrolidone)

Blending is a very effective method for manufacturing new polymeric materials; however, the process used to combine two polymers can influence the physicochemical properties of the final product. As such, the aim of this study was to investigate how the rapid removal of a solvent from a composite by the spray drying of partially hydrolyzed poly(vinyl alcohol) (PVA)/poly(vinyl pyrrolidone) (PVP) altered the solid‐state properties of the material compared to casting the blend within a film. Although thermal analysis showed that PVP acted as a plasticizer, reducing the melting point of PVA, spray drying the product rather than using a film‐casting procedure improved its solid‐state stability (increasing the glass transition) and resulted in the formation of a second crystalline phase within the material. Spectroscopic studies suggested that the manufacturing‐induced variance in the solid‐state properties of the PVA/PVP blends originated from structural differences in the composite caused by the processing method employed to form the blend. Although blending should still be considered a viable method of generating novel polymeric material, this study illustrated that through careful manipulation of the actual manufacturing process, the solid‐state properties of the product can be altered. This could open a whole range of novel applications for traditionally used polymer composites. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 2290–2299, 2005     

Immobilization of poly(ethylene imine) onto polymer films pretreated with plasma

Poly(ethylene imine) (PEI)‐immobilized surfaces have attracted much attention as interesting biomaterials in relation to cell culture, selective adsorption of endotoxins, and so on. In this study, we found that PEI could be effectively immobilized on various polymers pretreated by oxygen plasma. Surface analyses using an X‐ray photoelectron spectrometer and contents of peroxide groups determined by iodide method indicate that the hydroxy peroxides were the main functional groups that contributed to PEI immobilization covalently on the polymer surfaces treated with oxygen plasma. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 75: 576–582, 2000     

Poly(vinyl alcohol)/poly(vinyl pyrrolidone) interpenetrating polymer network: Synthesis and pervaporation properties

Novel interpenetrating polymer network membranes were made from poly(vinyl alcohol)/poly(vinyl pyrrolidone) blends of different compositions. The two polymer components were independently crosslinked chemically with glutaraldehyde and photochemically with 4,4′‐diazostilbene‐2,2′‐disulfonic acid disodium salt. The membrane performances were studied in pervaporation of tetrahydrofuran (THF)/water and THF/methanol mixtures. It was found that the membranes were excellent in THF dehydration, but much less efficient for the separation of THF/methanol mixtures. The pervaporation results were consistent with the membrane swelling data. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 89: 2808–2814, 2003     

Characterization of associating hydrogels of poly(vinyl alcohol) and poly(vinyl pyrrolidone)

In this study, hydrogels were prepared from blends of poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP). The miscibility of the polymers was confirmed with differential scanning calorimetry with the appearance of a single glass‐transition temperature. Additionally, a negative Flory–Huggins interaction parameter further verified the interaction between PVA and PVP. We evaluated the stability of the hydrogels by swelling the gels in phosphate‐buffered saline solutions at pH 7.4. With attenuated total reflectance‐Fourier transform infrared spectroscopy, it was determined that, during swelling, PVP dissolved out of the gel over time and the equilibrium gel content of PVP was nearly identical in all of the samples investigated. After the dissolution of PVP, the equilibrium water content of the gels ranged from 64 to 76 wt %. Additionally, rubber elasticity studies were performed to elucidate information about the physically crosslinked network structure. As determined from rubber elasticity experiments, the mesh size of the physically crosslinked hydrogels ranged from 90 to 230 Å. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Characteristics of poly(vinyl pyrrolidone)/poly(acrylic acid) interpolymer complex prepared by template polymerization of acrylic acid: Effect of reaction solvent and molecular weight of template

Poly(vinyl pyrrolidone) (PVP)/poly(acrylic acid) (PAA) interpolymer complexes were prepared, in ethanol or dimethylformamide (DMF), by template polymerization of acrylic acid in the presence of PVP (MW: 42.5 or 1100 K) used as the template. FTIR analysis showed that the complexes were formed through hydrogen bonding between the carboxyl groups of the PAA and the carbonyl groups of the PVP. The glass‐transition temperature (T_g) of the complex, prepared in ethanol, was higher than that of the component polymers, whereas the T_g of the complex, prepared in DMF, was located between that of the component polymers. The dissolution rate of the complex was affected by the molecular weight of the PVP and the reaction solvent. The release rate of ketoprofen from the complexes showed a pH dependency, and was slower at a lower pH. The ketoprofen release rate from the complex was controlled mainly by the dissolution rate of the complex above the pK_a of PAA (4.75) and by the diffusion rate below the pK_a. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 2390–2394, 2004     

Application of FTIR spectroscopy for structural characterization of ternary poly(acrylic acid)–metal–poly(vinyl pyrrolidone) complexes

The FTIR spectroscopic technique was used in the study of ternary polymer–metal complexes containing two polyelectrolytes of opposite charge and metal ions. The structure of the ternary (PAA‐Fe³⁺‐PVP) complexes was examined by following the changes in their infrared spectra. It was found that the shapes of the absorption bands of the resultant compounds are influenced by the presence of Fe³⁺. According to this result it was suggested that two types of structure which differ in the composition are formed, one of which results from the coordination of Fe³⁺ with PAA‐PVP complex and the other is due to the formation of Fe³⁺ polycarboxylate. Comparison between the spectrum of PAA‐PVP complex and those of the compounds resulted from the reaction between the two opposite charged electrolytes, PAA and PVP and each of the divalent metal chlorides NiCl₂, CoCl₂, CuCl₂, and ZnCl₂) led to the conclusion that a reaction took place between the divalent transition metal chlorides and the extent of reaction depends on the nature of metal ions and PAA‐PVP complex. The FTIR spectra of the precipitate resulted from the mixtures of PAA‐PVP and Ni(NO₃)₂ or Sr(NO₃)₂ were investigated. It was noted that the addition of Ni(NO₃)₂ or Sr(NO₃)₂ to the mixture of the electrolytes of PAA and PVP provoked appreciable changes in the characteristic spectral features of the complex resulting from the interaction of the metal ions with the polymer–polymer complex. The FTIR spectra of the precipitate resulted from the reaction between CeCl₃, ErCl₃, and LaCl₃ were also investigated. It was concluded that a reaction took place between the rare earth metals and the PPC. This means that ternary polymer–metal–polymer complexes were formed. The extent of changes in the spectral features differs from metal to metal according to the nature of metal ions. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Study of complexes of poly(vinyl pyrrolidone) with copper and cobalt on solid state

A polymer–metal complex is a metal complex containing a polymer ligand, showing a remarkably specific structure in which central metal ions are surrounded by a colossal polymer chain. Based on this polymeric ligand, the polymer–metal complex has interesting and important characteristics, especially catalytic activities. This activity is different from that of the corresponding ordinary metal complex of low molecular weight. In this work we studied the synthesis and characterization, in the solid state, of different poly(vinyl pyrrolidone)–cobalt (PVP/Co) and –copper (PVP/Cu) complexes. We used differential thermal analysis and FTIR as the experimental techniques. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 1512–1518, 2004     

Miscibility enhancement on the immiscible poly (vinyl pyrrolidone) and poly (ethyl methacrylate) with poly (vinyl phenol)

The miscibility behavior of ternary blends of poly (vinyl phenol) (PVPh)/poly (vinyl pyrrolidone) (PVP)/poly (ethyl methacrylate) (PEMA) was investigated mainly with calorimetry. PVPh is miscible with both PVP and PEMA on the basis of the single T_g observed over the entire composition range. FTIR was used to study the hydrogen bonding interaction between the hydroxyl group of PVPh and the carbonyl group of PVP and PEMA at various compositions. Furthermore, the addition of PVPh is able to enhance the miscibility of the immiscible PVP/PEMA and eventually transforms it into a miscible blend, especially when the ratio between PVP/PEMA is 3:1, probably because of favorable physical interaction. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1205–1213, 2006     

Electromagnetic properties of aluminosilicate‐filled polymer composites of poly(vinyl alcohol)–poly(vinyl pyrrolidone)

Nanocomposites of aluminocilicate are of growing interest not only because they offer exceptional reinforcement at very low filler concentrations, but also because of their electromagnetic properties and natural origin. Aluminosilicate‐filled biodegradable composites of poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) were prepared by a conventional solvent casting technique using glass plates as the casting surfaces. The aluminosilicate used in this study is a multicomponent natural clay material. Its average particle size is 23–24 nm. The dielectric and magnetic properties of composite materials of PVA‐PVP and aluminosilicate were investigated in wide frequency ranges from 1 MHz to 1 GHz. The complex permittivity spectra (ε* = ε′ – jε″) had a relaxation type frequency dispersion with an ill‐defined broad resonance line width of the dielectric losses (ε″). The magnetic properties of composites are very low and are independent of the filler concentration. The new nanobiocomposites are brick red in color and weakly ferromagnetic in nature. POLYM. COMPOS., 26:739–744, 2005. © 2005 Society of Plastics Engineers     

聚乙二醇/聚乙烯吡咯烷酮修饰的纳米Fe3O4粒子的制备与表征

为了获得能够在水中稳定分散,具有广泛应用前景的磁性纳米粒子,以不同分子量的聚乙烯吡咯烷酮(PVP)作为修饰剂,在聚乙二醇(PEG)中高温热分解乙酰丙酮铁(Fe(acac)₃)制备了纳米Fe₃O₄粒子。采用X射线粉末衍射仪(XRD)、透射电镜(TEM)、高分辨透射电镜(HRTEM)、超导量子干涉仪(SQUID)、热重分析仪(TGA)、傅里叶变换红外光谱仪(FT-IR)、纳米粒度与zeta电位分析仪对样品进行了表征,并对样品在生理盐水和生理缓冲液中的稳定性进行了研究,结果表明:制备的纳米Fe₃O₄粒子具有高的结晶度以及单分散性,在300 K下,具有超顺磁性和较高的饱和磁化强度;PEG和PVP共同修饰于纳米Fe₃O₄粒子表面,为纳米Fe₃O₄粒子提供了良好的水分散性;制备的纳米Fe₃O₄粒子在生理盐水和多种生理缓冲液中能够高度溶解并稳定地分散。水中的纳米Fe₃O₄粒子表面呈电中性,表面修饰层的空间位阻效应是所制备的纳米粒子在水溶液中高分散的原因。     

Controlled loading and release of methylene blue for hydrogen-bonded LbL poly(vinyl pyrrolidone)/poly (acrylic acid) film

The layer-by-layer (LbL) assembled multilayer films are widely used in controlled drug delivery. Here, hydrogen-bonded LbL multilayer films were assembled through alternating deposition of poly(vinylpyrrolidone) (PVPON) and poly(acrylic acid) (PAA) on glass slides. Methylene blue (MB) was used as a model drug to investigate the loading and release ability of the prepared multilayer film. The results showed that the loading rate of MB was greatly influenced by pH value of the dye solution, and the release rate was controlled both by ionic strength and pH value of immersing solution. The result also indicated that the loading and release of MB were reversible and can be repeated many times. It suggested that the PVPON/PAA multilayer film had potential applications in drug delivery and controlled release.     

Morphology,drug release behavior,thermal, and mechanical properties of poly(ethylene oxide) (PEO)/poly(vinyl pyrrolidone) (PVP) blends

Poly(ethylene oxide) (PEO)/poly(vinyl pyrrolidone) (PVP) blends containing different amounts of PVP (0, 10, 25, 50, and 100 wt %) prepared by a solution casting method were characterized in terms of microstructure, thermal, and mechanical properties along with their drug release behavior. Fourier‐transform infrared spectroscopy results confirmed formation of hydrogen bonds between PEO and PVP. Although scanning electron microscopy micrographs showed no phase separation in the blends, the elemental analysis data obtained by energy dispersive X‐ray technique revealed partial miscibility between the blend components. The miscibility of the blend and degree of crystallinity of PEO component of the blend were decreased with increasing PVP content of the blend. The nucleating role of PVP in crystallization of PEO was confirmed by differential scanning calorimetry analysis. A synergistic effect on mechanical properties was obtained as a result of blending PVP with PEO. The results of curcumin release studies from the films indicated that, the blends have lower diffusion coefficients and slower drug release rate as compared to the neat PEO. Theoretical analysis of the drug release data using Peppas's model revealed that the kinetic of drug release from all the films is governed by a non‐Fickian diffusion mechanism. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46403.