PVA Blend Research Articles

Synthesis of amphiphilic alginate derivatives and electrospinning blend nanofibers: a novel hydrophobic drug carrier

As a kind of novel hydrophobic drug carrier materials, the drug-loaded nanofibers were successfully fabricated using amphiphilic alginate derivative (AAD) and poly (vinyl alcohol) (PVA) by electrospinning method. The AAD was synthesized by amide linkage attachment of octylamine onto the carboxylic group of alginate, which was characterized by the means of elemental analysis, FT-IR spectrometer, 1H NMR spectrometer and fluorescence measurement. Experimental results showed the amidation of alginate was successful, in which the degree of modification was 0.27 and the critical aggregation concentration in 0.15 mol/L aqueous NaCl solution was 0.43 mg/mL. The octyl groups of AAD could effectively make alginate chains flexible and enhance chain entanglements through the hydrophobic interactions between octyl groups. In contrast to sodium alginate (SA)/PVA blend solutions, AAD/PVA blend solutions showed more excellent electrospinnability. Additionally, the different volume ratios of SA or AAD to PVA played an important role in the formation and morphology of the electrospun blend nanofibers. Although the amidation of alginate could not fundamentally alter the spinnability of alginate, the content of alginate in the blend nanofibers was appropriately increased. The new generated drug-loaded AAD/PVA (20/80) blend nanofibers exhibited relatively continuous and uniform nanofibers with the average diameter of 191.72 nm. Compared to the drug-loaded SA/PVA (20/80) blend nanofibers, the drug-loaded AAD/PVA (20/80) blend nanofibers presented a sustained release performance with the slow release of about 76 % λ-cyhalothrin during the initial period of 10 h.

Novel multifunctional colloidal carbohydrate nanofiber electrolytes with excellent conductivity and responses to bone cancer cells

This work presents a new approach to fabricating novel polymer nanofiber composites (NFCs) from water solution blends of PVA (hydrolyzed 89%)/ODA–MMT and Na–CMC/ODA–MMT nanocomposites as well as their folic acid (FA) incorporated modifications (NC-3-FA and NC-4-FA) through green electrospinning nanotechnology. The chemical and physical structures and surface morphology of the nanofiber composites were confirmed. Significant improvements in nanofiber morphology and size distribution of the NFC-3-FA and NFC-4-FA nanofibers with lower average means 110 and 113nm compared with those of NFC-1/NFC-2 nanofibers (270 and 323nm) were observed. The structural elements of polymer NFCs, particularly loaded partner NC-2, plays an important role in chemical and physical interfacial interactions, phase separation processing and enables the formation of nanofibers with unique morphology and excellent conductivity (NFC-3-FA 3.25×10−9S/cm and NFC-4-FA 8.33×10−4S/cm). This is attributed to the higher surface contact areas and multifunctional self-assembled supramacromolecular nanostructures of amorphous colloidal electrolytes. The anticancer activity of FA-containing nanofibers against osteocarcinoma cells were evaluated by cytotoxicity, apoptotic and necrotic analysis methods.

Evaluating the potential of chitosan/poly(vinyl alcohol) membranes as alternative carrier material for proliferation of Vero cells

AbstractChitosan/poly(vinyl alcohol) (CS/PVA) blend membranes were prepared using the casting method and their physiochemical properties were analyzed using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and X-ray diffraction (XRD). FTIR and XRD demonstrated possible hydrogen bonds between CS and PVA. The addition of PVA to CS resulted in surface roughness as analyzed by SEM. The CS/PVA blend membrane exhibited high tensile properties (81.62%) and reduced water-holding capacity (53.8%) compared to a pure CS membrane (control). Cell viability and proliferation were assessed via an MTT assay with Vero cell culture. Associated with improved physicochemical properties, the CS/PVA blend membrane promotes cell proliferation of Vero cells with high specific growth rate (0.582 day-1). The results demonstrate that the blending of CS and PVA could significantly alter the surface rugosity, water-holding capacity and improve the mechanical and biological properties of the membrane. Interestingly, this concept can be extended for different anchorage-dependent cell lines, as an alternative carrier material.

Improved separation and antifouling performance of PVA thin film nanocomposite membranes incorporated with carboxylated TiO2 nanoparticles

In this study, a series of thin film nanocomposite membranes was developed by coating a surface-modified porous poly (vinylidene fluoride) (PVDF) support with poly (vinyl alcohol) (PVA) doped solution containing TiO2 nanoparticles. In order to improve the interfacial adhesion of nanoparticles in the PVA blend, an endothermic carboxylation reaction under acidic conditions was carried out on the TiO2 surface using chloroacetic acid. Electron microscopy studies identified various topographies upon functionalization of the coating and incorporation of TiO2 nanoparticles. The carboxylation of TiO2 nanoparticles promoted particle dispersion within the PVA doped solution with significantly reduced particle agglomeration, demonstrating a potential solution to a significant difficulty in the synthesis of state-of-the-art nanocomposite membranes. Furthermore, the carboxylate functional groups on the TiO2 surface facilitated a strong interfacial crosslinking reaction with the hydroxyl groups in the PVA chains, conferring excellent interface integration between the nanoparticle and the polymer matrix. The high performance of this new carboxylated thin film nanocomposite membrane is evidenced by the improved membrane performance including solute rejection, antifouling properties and flux recovery ratio.

Thermal properties in strong hydrogen bonding systems composed of poly(vinyl alcohol), polyethyleneimine, and graphene oxide

Blends of poly(vinyl alcohol) (PVA), polyethyleneimine (PEI), and graphene oxide (GO) were prepared by solution casting method. Calorimetric thermal properties of the blends were investigated. The <TEX>$T_gs$</TEX> of PVA/PEI blends were higher than the <TEX>$T_gs$</TEX> of either of the component polymers at low concentrations of PEI. These abnormal increases of <TEX>$T_gs$</TEX> may be due to the negative entropy of mixing which is associated with strong hydrogen bonding between PVA and PEI. The degree of depression of <TEX>$T^0_ms$</TEX> was not reduced by the negative entropy of mixing, since strong hydrogen bonding also causes an increase in the magnitude of negative <TEX>${\chi}$</TEX> between PVA and PEI. The <TEX>$T_g$</TEX> of PVA was increased significantly by adding 0.7 wt.% GO into PVA. The magnitude of negative <TEX>${\chi}$</TEX> was increased by adding GO into the blends of PVA and PEI.

PVA/Polyelectrolyte Bipolar Membranes for Fuel Cell Applications

In the last few years, direct borohydride/hydrogen peroxide fuel cells (DB/HPFC) have attracted considerable attention due to their potential use as air-independent power sources in undersea vehicles. In general, a DB/HPFC system can be built using either a cation exchange membrane (CEM) or an anion exchange membrane (AEM) as a polymer electrolyte. Unfortunately, to date, these systems exhibited low efficiency, mainly due to some problems related to the intrinsic properties of the polymer electrolyte themselves. Bipolar membranes are promising candidates to improve the efficiency of DB/HPFC systems, since these incorporate advantageous features of both AEM and CEM, and also mitigate the loss of fuel.The present work focuses on the fabrication and characterization of a novel bipolar membrane for DB/HPFC applications. The first goal is to fabricate water-soluble PVA-based AEM and CEM with both high ionic conductivity and excellent mechanical stability. For this purpose, a variety of AEMs are prepared via polymer blending of PVA and poly(diallyldimethylammonium chloride) (PDDA) or poly(acrylamide-co-diallyldimethylammonium chloride) (PACoDDA). Similarly, CEMs are fabricated via polymer blending of PVA and acid polymer ((poly (styrene sulfonic acid) (PSSA) or poly (acrylic acid) (PAA)). Subsequently, the membranes are cross-linked using a chemical or physical method. The chemical cross-linking is performed at different concentrations of glutaraldehyde (GA), whereas the physical cross-linking is performed at different temperatures. The electrical, mechanical and morphological properties of these membranes are evaluated as a function of PVA content and cross-linking process conditions. Some of the material characterization techniques used in this study include, but are not limited to: Fourier transform infrared spectroscopy (FTIR), four-electrode impendence measurement, transmission electron microscopy (TEM), and tensile tests. Preliminary results indicate that PVA-PDDA and PVA-PSS membranes have excellent mechanical and alkaline stability. Also, the maximum OH− conductivity of 8.57E-3 S cm−1 was achieved for physically cross-linked PVA/PDDA membrane with a polymer composition of 70/30 as shown in Figure 1a. In the case of CEM, the high H+ conductivity of 1.77E-2 S cm−1 corresponds to the chemically cross-linked PVA-PSS membrane with a polymer composition of 70:30 (see Fig. 1b). Figure 1. Ionic conductivity as a function of PVA content for (a) PVA/PDDA membranes and (b) PVA/PSS membranes.

English

There is an increasing demand for designing controlled drug delivery systems with materials which are more biocompatible, economical and materials which can be processed easily. Poly (vinyl alcohol) (PVA) and hyaluronic acid (HA) are promising polymers for applications in drug delivery. PVA forms gel based on the acetal bridges when crosslinked with glutaraldehyde (GA). On the other hand, HA a natural polymer, forms gel with divinyl sulfone (DVS) as a crosslinker. PVA and HA blends upon crosslinking PVA with GA or HA with DVS, in the presence of the other polymer, form gels that are more adaptable to the drug delivery systems. In this work, the mechanical properties and swelling behaviour of PVAHA gels were characterized. The effect of composition on viscoelastic moduli and degree of swelling was determined. The storage modulus (G″) of various gels made of PVA, HA and PVAHA blends were measured using rheology and compared with the values available in the literature. Swelling properties were measured and compared among various PVA and HA gels. Collagen is added to PVA solution and the rheological properties were measured in the gel state. Based on the values of storage modulus, gels of various compositions of PVA, HA and collagen might be selected as potential biomaterials for drug delivery system depending on careful understanding the type of application.

Novel Technology to Improve Drug Loading in Polymeric Nanofibers

The objective of the present study is to elaborate a new approach for drug loading into electrospun nanofibers through active loading based on non-solvent evaporation technique. The polymeric nanofibers were achieved by electrospinning method using PCL, PVA and a blend of sodium alginate & PVA as polymeric constituents. Different methods such as passive & active (solvent and non-solvent evaporation methods) techniques were used to prepare drug loaded nanofibers. The resulting nanofibers were characterized for morphology, drug loading, in-vitro release and degree of swelling. Different kinetic models were applied to the in-vitro release profile of different polymeric nanofibers. The prepared nanofibers were found to be uniform, non-beaded and non-woven with fiber diameter ranging from 200-450nm. Entrapment efficiency of metronidazole was increased by 30% when non-solvent evaporation method was used. Moreover the n value obtained from the Peppas model varied between 0.8-0.9 which was further confirmed that the mechanism of drug release was anomalous diffusion which refers to combination of both diffusion and erosion mechanism. The impetus for this development was that the non-solvent evaporation technique can be successfully used for drug loading to polymeric nanofibers.

Structural characterization of hydrophilic polymer blends/montmorillonite clay nanocomposites

ABSTRACTThe nanocomposite films comprising polymer blends of poly(vinyl alcohol) (PVA), poly(vinyl pyrrolidone) (PVP), poly(ethylene oxide) (PEO), and poly(ethylene glycol) (PEG) with montmorillonite (MMT) clay as nanofiller were prepared by aqueous solution casting method. The X‐ray diffraction studies of the PVA–x wt % MMT, (PVA–PVP)–x wt % MMT, (PVA–PEO)–x wt % MMT and (PVA–PEG)–x wt % MMT nanocomposites containing MMT concentrations x = 1, 2, 3, 5 and 10 wt % of the polymer weight were carried out in the angular range (2θ) of 3.8–30°. The values of MMT basal spacing d001, expansion of clay gallery width Wcg, d‐spacing of polymer spherulite, crystallite size L and diffraction peak intensity I were determined for these nanocomposites. The values of structural parameters reveal that the linear chain PEO and PEG in the PVA blend based nanocomposites promote the amount of MMT intercalated structures, and these structures are found relatively higher for the (PVA–PEO)–x wt % MMT nanocomposites. It is observed that the presence of bulky ester‐side group in PVP backbone restricts its intercalation, whereas the adsorption behavior of PVP on the MMT nanosheets mainly results the MMT exfoliated structures in the (PVA–PVP)–x wt % MMT nanocomposites. The crystallinities of the PEO and PEG were found low due to their blending with PVA, which further decreased anomalously with the increase of MMT concentration in the nanocomposites. The decrease of polymer crystalline phase of these materials confirmed their suitability in preparation of novel solid polymer nanocomposite electrolytes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40617.

Binding of Zn(II) ions to chitosan–PVA blend in aqueous environment: Adsorption kinetics and equilibrium studies

Zinc ion [Zn(II)] is the one of the most toxic and common among the heavy metal pollutants of industrial effluents. The present investigation has been aimed at describing the synthesis and characterization of biodegradable nanoparticle based on chitosan, then blending with biodegradable synthetic polymer (polyvinyl alcohol, PVA) and which was applied for the removal of Zn(II) ions from the aqueous system. The prepared nanoparticle and the chitosan blended polymers were characterized using transmission electron microscope (TEM), scanning electron microscope (SEM), and X‐ray diffraction (XRD) analyses. The adsorption behaviour of chitosan blended polymer for Zn(II) ions has been studied as a function of solution pH, adsorbent dose, contact time, and adsorbate concentration in a batch system. The maximum adsorption was observed as 99.45% for an initial Zn(II) ions concentration of 10 mg/L for the solution pH of 5.0 and contact time of 30 min and at 5 g/L of adsorbent dose. The adsorption kinetics was investigated by fitting the experimental data to the pseudo‐first order, pseudo‐second order kinetic models, Weber and Morris intraparticle diffusion and Boyd kinetic models. Adsorption equilibrium data were analyzed by the Langmuir and Freundlich adsorption isotherm models and it was found that the Langmuir isotherm model fits best with the experimental data. The desorption of Zn(II) ions from the spent chitosan/PVA blend was carried out by HCl solution. The results of the present study showed the polymer blends may act as an effective adsorbent for the removal of Zn(II) ions from the aqueous solution. © 2014 American Institute of Chemical Engineers Environ Prog, 34: 15–22, 2015

Functionalized chitosan derived novel positively charged organic–inorganic hybrid ultrafiltration membranes for protein separation

Positively charged organic–inorganic hybrid ultrafiltration membranes for selective protein separation were fabricated from blends of PVA, functionalized600 dpi in TIF format)??&gt; chitosan and tetraethylorthosilicate.

Synthesis, characterization, and in vitro studies of graphene oxide/chitosan–polyvinyl alcohol films

Nanocomposites based on chitosan–polyvinyl alcohol (CS–PVA) and graphene oxide (GO) were prepared by casting the stable aqueous mixture of the components. SEM, TEM and X-ray diffraction showed that graphene oxide is largely dispersed on molecular scale within CS–PVA matrix. FTIR investigation indicated the occurrence of some interaction between graphene oxide nanosheets and CS–PVA. The obtained composites are mechanically strong and exhibit improved thermal stability. By addition of 6wt.% GO within CS–PVA blend, the elastic modulus increased over 200%. The cell viability and proliferation results showed that MC3T3-E1 mouse osteoblastic cells can adhere and developed on the CS–PVA/GO composite films. A significant proliferation potential was displayed by the cells in contact with CS–PVA/GO 6wt.%. Graphene oxide reinforced CS–PVA with high mechanical and bioactive properties are potential candidates for tissue engineering.

Rheology and structure of poly(vinyl alcohol)-poly(ethylene glycol) blends during aging

We have used rheometry and dynamic light scattering to study the evolution of the properties of concentrated aqueous solutions of poly(vinyl alcohol) (PVA) and blends of PVA and poly(ethylene glycol) (PEG) as they age. We find that freshly prepared materials are primarily viscous, though they shear thin at low-shear rates and show signs of shear-induced structure at higher shear rates. The viscosity of pure PVA solutions increases slowly as they age. The aging of the PVA/PEG blends is much faster, however, and for sufficiently high concentrations of PEG, the blends gel over the 1-month time scale of our observations. Dynamic light scattering experiments show the presence of two relaxation processes in both the pure PVA solution and the blends, with relaxation times that depend on the polymer concentration and the aging time. Both the rheological and dynamic light scattering measurements show the existence of microphase separation in the blends and suggest that the presence of PEG forces the PVA solution to phase separate and eventually to gel. However, we find that the gel transition is not sharp, with different signatures of gelation occurring at different times, depending on the length scale at which the gel is probed.

Physical properties of PVA doped with algal glycerol

ABSTRACTPhysical behavior of membrane blends of poly(vinyl alcohol) (PVA) doped with different weight percentage (wt %) of algal glycerol is reported. Solid‐state PVA/glycerol membranes were prepared by the solution casting method. Electrical impedance measurements were conducted to test the effect of varying the percentage of glycerol on the conductivity of the membranes. The measurements were made in the frequency and temperature ranges 1 Hz–1 MHz and 303–423 K, respectively. It was observed that the ionic conductivity increased with the increase of glycerol concentration as well as temperature. The thermal properties of the films were characterized. It was found that the thermal properties, particularly the melting point (Tm), for PVA blends exhibit a reduced value proportional to the algal glycerol content. Fourier transform infrared spectroscopy was utilized to evaluate the interactions between the glycerol and PVA. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4482–4489, 2013

Electrospun pullulan/poly(vinyl alcohol)/silver hybrid nanofibers: Preparation and property characterization for antibacterial activity

Nanofibers composed of pullulan (PULL), poly(vinyl alcohol) (PVA) and silver (Ag) were prepared using an electrospinning method in aqueous solutions. Field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR), thermal gravimetric analysis (TGA), antibacterial activity, and mechanical measurement were undertaken in order to characterize the PULL/PVA/Ag nanofiber morphology and properties. XRD and FTIR data demonstrated that there were good interactions between PULL and PVA possibly caused by hydrogen bonds. Moreover, XRD data and TEM images support the coexistence of a Ag and PULL/PVA blend matrix where Ag nanoparticles are well distributed. The study shows that the thermal stability in the mid-point temperature of the degradation and tensile strength of PULL could be increased with blending of PVA. It was also found that the Ag content could increase thermal stability and intensify antibacterial activity of the blend nanofibers. Since PULL and PVA are water-soluble and biocompatible polymers, the blended system can be considered one of the best materials for the preparation of excellent antibacterial nanofibers confirmed by a preservation test showing that the prepared material is suitable as a new preservative.

Biodegradation of polyvinyl alcohol-low linear density polyethylene-blended plastic film by consortium of marine benthic vibrios

Marine bacteria, Vibrio alginolyticus and Vibrio parahemolyticus isolated from sediments were evaluated for their ability as a consortia, to degrade polyvinyl alcohol-low linear density polyethylene (PVA-LLDPE)-blended plastic films in shake flask conditions at 120 rpm at 37 °C over 15 weeks. Results indicated that relatively 20 % decrease in tensile strength of the film could be achieved with 25 and 30 % blend of PVA in the PVA-LLDPE plastic film compared to other ratios. Micrographs obtained with scanning electron microscope showed visible cracks and grooves on the surface of the PVA-LLDPE blend film after 15 weeks of incubation with bacterial consortium. The decrease in tensile strength of the PVA-blended plastic films after treatment and the results of the scanning electron microscopic analysis evidence that the consortium could cause degradation of PVA-LLDPE plastic blends compared to suitable controls. This is the first report on polyvinyl alcohol degrading Vibrio sp. from marine sediments and its application in microbial degradation of polyvinyl alcohol-low linear density polyethylene plastic blends. The study indicated potential of marine benthic vibrios that have novel enzymes and unique characteristics for application in bioremediation and solid waste management particularly in handling synthetic polymers such as PVA-blended plastic films.

Guar gum and guar gum-oligomeric poly(vinyl alcohol) blends as novel flocculants for kaolinated waste water

This is probably the first report on kaolin flocculation done with aqueous guar gum (GG) at various pH. Dynamic light scattering and reduced viscosity proved the polyelectrolytic feature (zeta potential) of aqueous GG which changed on changing pH. Interestingly, the molecular size of GG did not always increased with rising zeta potential due to strong intermolecular repulsion leading to macromolecular recoiling. Best pH range for settling was 4.0–5.0 which included isoelectric point (IEP) of kaolin. Post-settling turbidity was also acceptable at that range. Optimized GG was further blended with oligomeric poly (vinyl alcohol) (PVA) (Mn 14,000) to prepare a new set of flocculant. Oligomeric PVA was previously optimized at similar pH as excellent kaolin flocculant in our earlier investigation. All GG–PVA blends including neat GG exhibited faster settling than neat PVA. However, settling times of all blend compositions were slightly greater than that of neat GG except for few cases where the post settling turbidity was found significantly lower than all our previous investigations.

Novel Starch‐Based PVA Thermoplastic Capsules for Hydrophilic Lipid‐Based Formulations

For decades, gelatin has been used in the rotary die process as a shell-forming material of soft capsules because of its unique physicochemical properties. However, with respect to the encapsulation of comparatively hydrophilic lipid-based formulations, gelatin has one considerable drawback: Immediately after production, the capsule shell contains a large amount of water (up to 35%). There is the potential for water to migrate from the capsule shell into the formulation, which will lead to a decrease in drug solubility and, in turn, the potential for drug crystallization. The present study introduces a novel capsule material that was obtained from extrusion. The starch-based polyvinyl alcohol thermoplastic capsules (S-PVA-C) mainly comprised a blend of starch and PVA. Gelatin and the novel material were used to encapsulate a hydrophilic lipid-based system of fenofibrate. Considerable water migration was observed from the soft gelatin shell to the hydrophilic formulation during drying and drug crystallization resulted in soft gelatin capsules. In contrast, S-PVA-C displayed no substantial water exchange or drug crystallization upon storage. The thermoplastic capsule material further exhibited more surface roughness and higher resistance to mechanical deformation compared with gelatin. In conclusion, S-PVA-C provided a robust drug product following encapsulation of a rather hydrophilic lipid-based formulation.

Influence of the nanoparticle type on the thermal decomposition of the green starch/poly(vinyl alcohol)/montmorillonite nanocomposites

In this study, some aspects concerning the thermal decomposition of starch/poly(vinyl alcohol) (PVA)/montmorillonite (MMT) nanocomposites with 2 wt% nanoclay, prepared by melt mixing method, were studied. For these loadings, the inorganic fillers are well dispersed through the PVA/starch matrix, i.e., the nanocomposites formed are mostly intercalated hybrids. The aim of this article is to establish the effect of the nanofiller nature on the thermal decomposition of the starch/PVA/MMT nanocomposites. The thermal behavior of the 50 wt% starch/50 wt% PVA blend and its nanocomposites with 2 wt% nanoclay has been investigated by thermogravimetric analysis coupled with Fourier transform-infrared spectroscopy and mass spectrometry (MS). The volatile compounds resulting during the thermal degradation were studied by in situ vapor phase FT-IR spectroscopy and MS technique under a controlled temperature/time program. Apart from the identification of the volatile compounds, some conclusions on the nanoclays effect on the degradation mechanism and formation of the volatile compounds in accordance with the previously developed general mechanisms for PVA and starch degradation have been formulated. The clay–PVA/starch nanocomposites show completely different degradation product distribution patterns, which may be attributed to the presence of the head-to-head structures and Si–O–C linkages formed between clay and blend components.

Effects of Different Moisture Contents on Physical Properties of PVA-Gelatin Films

In this work, it was investigated the effect of different moisture contents on PVA-gelatin films by means of dielectric properties, infrared spectroscopy, microwave response and gravimetric method. The films were elaborated from a blend of gelatin and PVA, with 0 and 25 % glycerol. The sorption isotherms were determined by gravimetric methods, at 25 °C. A capacimeter was used for dielectric measurements, and a device called SOLFAN setup was used for microwave measurements. The sorption isotherms were markedly affected by the glycerol content and relative humidity, due to the hygroscopic nature of the films. The dielectric constant and the microwave response signal were also strongly affected by the moisture and glycerol content in the films. Finally, Infrared spectra showed some changes in the amide peak positions, attributed to the modifications in the interactions between the macromolecules. The behaviors obtained in this work were explained on the basis the way the water enters in the film matrix.