Poly Vinyl Methyl Research Articles

Polyvinyl alcohol dyed with methyl red as a radiochromic film dosimeter for gamma radiation

Abstract A Radiochromic film dosimeter for gamma radiation was prepared from polyvinyl alcohol (PVA) and methyl red (MR) by condensation polymerization. To confirm the reaction, the obtained PVA-MR film was characterized by Fourier-transform infrared spectroscopy (FTIR) and compared to PVA film. The result shows the appearance of new vibrational stretching at ~1700 cm−1, related to carbonyl groups, indicating that the reaction between PVA and MR has been successfully done. The effect of radiation on the color change characteristic of PVA-MR film and its possibility to be used as a radiochromic film dosimeter were investigated using ultraviolet (UV)-Vis spectrophotometry. The absorption spectrum of PVA-MR can be seen in the visible region at ~420 nm, which is characteristic of red, and the film undergoes decolorization gradually from red to transparent when exposed to gamma radiation up to 100 kGy. Moreover, the response of these dosimeters at different times after irradiation was tested and the energy band gap, Eg, was also calculated.

Strategies for overcoming the lung surfactant barrier and achieving success in antimicrobial photodynamic therapy

The impressive increase in antimicrobial resistance has required the development of alternative treatments that act on multiple non-specific molecular targets and are effective against a broad range of microorganisms. Antimicrobial Photodynamic Therapy (aPDT) is based on microbial inactivation from oxidative stress and represents an important tool for inactivating microorganisms with low risk of resistance selection. Therefore, our research group has been devoted to demonstrating its effectiveness against pathogens that cause pneumonia, one of the most lethal infections worldwide. Previous studies reported the efficiency and safety of an in vitro photoinactivation protocol for Streptococcus pneumoniae and the delivery of infrared light (external illumination) and photosensitizer (PS) in an animal model. However, the in vivo inactivation of microorganisms still poses challenges due to the presence of lung surfactant (LS), which traps PSs, preventing them from reaching the microbial target. This study investigated different approaches such as use of emulsifiers, perfluorocarbon, oxygen nanobubbles, and copolymer towards overcoming LS and optimizing aPDT response. The most promising strategy consisted in combining indocyanine green (ICG) with GantrezTM AN-139 - a Polyvinyl Methyl Ether/Maleic Anhydride copolymer (PVM/MA) – showing high microbial inactivation and safety for human lung epithelial (A549) and fibroblast (MRC-9) cell lines. The in vitro experiments provided an alternative to overcome the limited PS distribution through LS and will serve as the basis for in vivo studies.

Selenium Nanoparticles Synergize with a KRAS Nanovaccine against Breast Cancer.

Selenium (Se) is an element crucial for human health, known for its anticancer properties. Although selenium nanoparticles (SeNPs) have shown lower toxicity and higher biocompatibility than other Se compounds, bare SeNPs are unstable in aqueous solutions. In this study, several materials, including bovine serum albumin (BSA), chitosan, polymethyl vinyl ether-alt-maleic anhydride, and tocopherol polyethylene glycol succinate, are explored to develop stable SeNPs and further evaluate their potential as candidates for cancer treatment. All optimized SeNP are spherical, <100nm, and with a narrow size distribution. BSA-stabilized SeNPs produced under acidic conditions present the highest stability in medium, plasma, and at physiological pH, maintaining their size ≈50-60nm for an extended period. SeNPs demonstrate enhanced toxicity in cancer cell lines while sparing primary human dermal fibroblasts, underscoring their potential as effective anticancer agents. Moreover, the combination of BSA-SeNPs with a nanovaccine results in a strong tumor growth reduction in an EO771 breast cancer mouse model, demonstrating a three-fold decrease in tumor size. This synergistic anticancer effect not only highlights the role of SeNPs as effective anticancer agents but also offers valuable insights for developing innovative combinatorial approaches using SeNPs to improve the outcomes of cancer immunotherapy.

Thermo‐responsive polymer to clean fouled forward osmosis membrane after wastewater treatment: Excellent flux recovery

AbstractThermally responsive polymers (TRPs) have gained significant attention in the past decade due to their unique phase transition behavior, those exhibiting changes in properties with temperature variations. In water, hydrophilic block copolymers form helical structures that can transform into hydrophobic globules above the lower critical solution temperature (LCST). Fouling is one of the limiting issues for the forward osmosis (FO) process in wastewater treatment. In this work, after the treatment of wastewater from the paper and pulp industries, foulants were removed from the surface of the commercial polyamide thin‐film composite membrane of the FO process using polyvinyl methyl ether (PVME), a TRP with an LCST of 35–37°C. PVME was mixed with different aqueous solutions to form cleaning solutions. Foulant cleaning experiments utilized a 1% PVME (w/v) solution in 300 mL of de‐ionized (DI) water, while 1 M NaCl solution served as the draw solution (DS) in the FO process. Comparing the water flux (J) and change in membrane hydraulic resistance (Rf) among pristine, fouled, and cleaned membranes revealed a 56.67% increase in water flux and a 51.68% decrease in membrane resistance after PVME mixed with DI water cleaning solution showcasing its effectiveness in improving membrane performance and reducing fouling. The cleaning efficiency of two solutions, that is, 1% PVME mixed in DI water and 1% PVME mixed in 1 M aqueous urea solution, is compared. Results showed that the former cleaning solution helped to obtain 32.62% higher water flux and 56.05% less membrane resistance. Various membrane characterizations are performed, such as field emission scanning electron microscopy (FE‐SEM), which characterizes the membrane's pore structure and surface morphology, while a contact angle analyzer assesses hydrophilicity. This research highlights the use of TRPs as effective cleaning agents, enhancing membrane performance by effectively removing foulants on the membrane surface. Investigating alternative cleaning solutions also provides insights for optimizing water treatment processes.Highlights Cleaning of fouled thin‐film composite membrane using thermal‐responsive polymers (TRPs). Polyvinyl methyl ether, a TRP with an lower critical solution temperature of 35–37°C used as a cleaning agent. 60% increase in water flux was observed after the single‐step cleaning process. Multiple uses of TRP for cleaning performed with no membrane damage.

Mucoadhesive Polymeric Polyologels Designed for the Treatment of Periodontal and Related Diseases of the Oral Cavity.

The study objective was to design and characterise herein unreported polyologels composed of a range of diol and triol solvents and polyvinyl methyl ether-co-maleic acid (PVM/MA) and, determine their potential suitability for the treatment of periodontal and related diseases in the oral cavity using suitable in vitro methodologies. Polyologel flow and viscoelastic properties were controlled by the choice of solvent and the concentration of polymer. At equivalent polymer concentrations, polyologels prepared with glycerol (a triol) exhibited the greatest elasticity and resistance to deformation. Within the diol solvents (PEG 400, pentane 1,5-diol, propane 1,2-diol, propane 1,3-diol, and ethylene glycol), PEG 400 polyologels possessed the greatest elasticity and resistance to deformation, suggesting the importance of distance of separation between the diol groups. Using Raman spectroscopy bond formation between the polymer carbonyl group and the diol hydroxyl groups was observed. Polyologel mucoadhesion was influenced by viscoelasticity; maximum mucoadhesion was shown by glycerol polyologels at the highest polymer concentration (20% w/w). Similarly, the choice of solvent and concentration of PVM/MA affected the release of tetracycline from the polyologels. The controlled release of tetracycline for at least 10 h was observed for several polyologels, which, in combination with their excellent mucoadhesion and flow properties, offer possibilities for the clinical use of these systems to treat diseases within the oral cavity.

Film-Forming Polymers for Inhibition of Hydroxyapatite Dissolution: A Screening Study

The aim of this study was to evaluate the effect of film-forming polymer solutions of different concentrations and pH values, either associated or not with sodium fluoride (F; 225 ppm F⁻), when applied during the initial stage of salivary pellicle formation, to prevent the dissolution of hydroxyapatite (HA), which was determined by the pH-stat method. Polyacrylic acid (PA), chitosan, sodium linear polyphosphate (LPP), polyvinyl methyl ether/maleic anhydride (PVM/MA), and propylene glycol alginate (PGA) were tested in three concentrations (lower, medium, and higher), two pH values (native or adjusted), and either associated or not with F. Distilled water, F, and stannous ion+fluoride (Sn/F; 225 ppm F⁻ and 800 ppm Sn²⁺, as SnCl₂) solutions were the controls, totalizing 63 groups. HA crystals were pretreated with human saliva for 1 min to allow pellicle formation, then immersed in the experimental solutions (1 min), and exposed to saliva for another 28 min. Subsequently, they were added to a 0.3% citric acid solution (pH = 3.8), connected to a pH-stat system that added aliquots of 28 μL 0.1 N HCl for a total reaction time of 5 min. Data were analyzed with one-way ANOVA and Tukey’s tests (α = 0.05). For PA alone, the concentrations of 0.1% (native pH), 0.06%, and 0.08% (both pH adjusted) showed significantly lower HA dissolution than the negative control. PA concentrations of 0.1% and 0.08%, of both pH values, improved the effect of F against HA dissolution to a near-identical value as Sn/F. All solutions containing chitosan and LPP significantly reduced HA dissolution in comparison with the control. For chitosan, the concentration of 0.5% (in both pH values) improved the effect of F. LPP at 0.5% (native pH) and all associations of LPP with F outperformed the effect of F. Some PVM/MA solutions significantly reduced HA dissolution but PVM/MA could not improve the protection of F. PGA was incapable of reducing HA dissolution or improving F effect. It was concluded that chitosan, LPP, and some PA and PVM/MA solutions used alone were capable of reducing HA dissolution. Only PA, chitosan, and LPP were able to enhance fluoride protection, but for PA and chitosan, this was influenced by the polymer concentration.

First evidence of microplastic pollution in the surface water of Malaysian Marine Park islands, South China Sea during COVID-19

Malaysia is bounded by the South China Sea with many islands that support species megadiversity and coral reef ecosystems. This study investigates the distribution of microplastics (MPs) in the surface water around the four marine park islands (Perhentian, Redang, Kapas, and Tenggol) during COVID-19. The global pandemic has reset human activities, impacting the environment while possibly reducing anthropogenic contributions of microplastic pollution near the South China Sea islands. It was found that Pulau Perhentian recorded the most abundance of MPs (588.33 ± 111.77 items/L), followed by Pulau Redang (314.67 ± 58.08 items/L), Pulau Kapas (359.8 ± 87.70 items/L) and Pulau Tenggol (294.33 ± 101.64 items/L). Kruskal-Wallis analysis indicates a significant difference in total MPs abundance between islands. There are moderate correlations between salinity, pH, temperature and MPs variability. Among these parameters, only temperature is significant (p < 0.05) as proven by the principal component analysis and multiple linear regression analysis. Nearly 99 % of MPs are fiber type, with the majority of them being black and transparent. Micro-FTIR spectroscopy revealed polyethylene, polypropylene, polyvinyl methyl ether, polyamide, phenoxy-resins and polyurethane-acrylic are associated with MPs. The findings provide a new baseline reference for the MPs distribution on Malaysian islands, which contributes to a potential future direction regarding marine sustainability.

Co-delivery of gentiopicroside and thymoquinone using electrospun m-PEG/PVP nanofibers: In-vitro and In vivo studies for antibacterial wound dressing in diabetic rats

Nanofibers (NFs) provide several delivery advantages like their great flexibility and similarity with extracellular matrix (ECM) which qualify them to be the unique model of a wound dressing. NFs could create mats of polymeric matrix loaded with an active agent enhancing its solubility and stability. In our study, Gentiopicroside (GPS) and Thymoquinone (TQ) loaded in NFs polymeric mats composed of coblended polyvinyl pyrrolidine (PVP) and methyl ether Polyethylene glycol (m-PEG) were fabricated via electrospinning technique. A morphological study using Scanning Electron Microscopy (SEM) was performed for all formulae as well as in vitro release study using High-performance Liquid chromatography (HPLC) for sample analysis. The optimized formula (F3) was chosen for further assays using Fourier-Transform Infrared Spectroscopy (FTIR), and Differential Scanning Calorimetry (DSC). Study of the antibacterial effect, and in vivo healing action for diabetic infected wounds to quantify Tumor necrosis factor-alpha and Cyclooxygenase-2 were also investigated. F3 achieved the highest % cumulative release (99.79 ± 6.47 for GPS and 96.89 ± 6.87 for TQ) at 60 min, and a smaller diameter (200 nm) showing significant anti-bacterial effects with well-organized skin architecture demonstrating great healing signs. Our results revealed that m-PEG/PVP NFs mats loaded with GPS and TQ could be considered an optimal wound care dressing.

Investigation and Optimization of Hydrogel Microneedles for Transdermal Delivery of Caffeine.

Caffeine is therapeutically effective for treating apnea, cellulite formation, and pain management. It also exhibits neuroprotective and antioxidant activities in different models of Parkinson's disease and Alzheimer's disease. However, caffeine administration in a minimally invasive and sustainable manner through the transdermal route is challenging owing to its hydrophilic nature. Therefore, this study demonstrated a transdermal delivery approach for caffeine by utilizing hydrogel microneedle (MN) as a permeation enhancer. The influence of formulation parameters such as molecular weight (MW) of PMVE/MA (polymethyl vinyl ether/maleic anhydride) copolymer and sodium bicarbonate (NaHCO3) concentration on the swelling kinetics and mechanical integrity of the hydrogel MNs was investigated. In addition, the effect of different MN application methods and needle densities of hydrogel MN on the skin insertion efficiency and penetration depth was also evaluated. The swelling degree at equilibrium percentage (% Seq) recorded for hydrogels fabricated with Gantrez S-97 (MW = 1,500,000 Da) was significantly higher than formulation with Gantrez AN-139 (MW = 1,080,000 Da). Increasing the concentration of NaHCO3 also significantly increased the % Seq. Moreover, a 100% penetration was recorded for both the applicator and combination of applicator and thumb pressure compared with only 11% for thumb pressure alone. The average diameter of micropores created by the applicator method was 62.94 μm, which was significantly lower than the combination of both applicator and thumb pressure MN application (100.53 μm). Based on histological imaging, the penetration depth of hydrogel MN increased as the MN density per array decreased. The hydrogel MN with the optimized formulation and skin insertion parameters was tested for caffeine delivery in an in vitro Franz diffusion cell setup. Approximately 2.9 mg of caffeine was delivered within 24 h, and the drug release profile was best fitted to the Korsmeyer-Peppas model, displaying Super Case II kinetics. In conclusion, a combination of thumb and impact application methods and reduced needle density improved the skin penetration efficiency of hydrogel MNs. The results also show that hydrogel MNs fabricated from 3% w/w NaHCO3 and high MW of copolymer exhibit optimum physical and swelling properties for enhanced transdermal delivery.

Standardization of Different Pre-sowing Seed Treatments on Growth, Yield and Yield Attributing Traits of Wheat (Triticum aestivum L.) var. DBW-187

The present study entitled, “Standardization of different pre-sowing seed treatments on growth, yield and yield attributing traits of wheat (Triticum aestivum L.) var. DBW-187.” was carried out to assess the effect of electric priming, magnetic priming and bio-filming of varying stickers with polyvinyl glycol, methyl cellulose and alginate with an objective during Rabi 2021-2022 to find the promising pre-sowing treatment for wheat. The results indicated that all treatment recorded significant variation for growth and yield attributes that were studied and performed well to the untreated control (T0). The treatment T6- Electric priming @200m Amp for 60 sec. significantly recorded the field emergence of 94.00 %, 9.59 tillers per plant, test weight of 42.49 g, seed yield of 7.82 g per plant, seed yield of 477.22 g per plot, seed yield of 34.77q per hectare, 56.71q biological yield per hectare, 61.30% of harvest index, B:C ratio of 1.14 with gross returns of 69,540.00/- and net returns of 37,055/- respectively and found to be promising and can be suggested for commercial cultivation.

An Investigation into the PVA:MC:NH4Cl-Based Proton-Conducting Polymer-Blend Electrolytes for Electrochemical Double Layer Capacitor (EDLC) Device Application: The FTIR, Circuit Design and Electrochemical Studies.

In this report, the preparation of solid polymer electrolytes (SPEs) is performed from polyvinyl alcohol, methyl cellulose (PVA-MC), and ammonium chloride (NH4Cl) using solution casting methodology for its use in electrical double layer capacitors (EDLCs). The characterizations of the prepared electrolyte are conducted using a variety of techniques, including Fourier transform infrared spectroscopy (FTIR), electrical impedance spectroscopy (EIS), cyclic voltammetry (CV), and linear sweep voltammetry (LSV). The interaction between the polymers and NH4Cl salt are assured via FTIR. EIS confirms the possibility of obtaining a reasonably high conductance of the electrolyte of 1.99 × 10−3 S/cm at room temperature. The dielectric response technique is applied to determine the extent of the ion dissociation of the NH4Cl in the PVA-MC-NH4Cl systems. The appearance of a peak in the imaginary part of the modulus study recognizes the contribution of chain dynamics and ion mobility. Transference number measurement (TNM) is specified and is found to be (tion) = 0.933 for the uppermost conducting sample. This verifies that ions are the predominant charge carriers. From the LSV study, 1.4 V are recorded for the relatively high-conducting sample. The CV curve response is far from the rectangular shape. The maximum specific capacitance of 20.6 F/g is recorded at 10 mV/s.

Factors influencing the swelling behaviour of polymethyl vinyl ether-co-maleic acid hydrogels crosslinked by polyethylene glycol

In past decades, polyethylene glycol (PEG) crosslinked polymethyl vinyl ether-co-maleic acid (PMVE/MA) hydrogel systems have been studied for various biomedical applications, mainly in the field of drug delivery. Nevertheless, successful delivery of clinically relevant dosage, especially high molecular weight drugs is still a major hindrance for this hydrogel system which delays its progress into clinical trials. Since the swelling property of this hydrogel plays a crucial role in its effectiveness as a drug delivery vehicle, we have investigated the influence of environmental factors such as pH, crosslinking temperature and swelling medium on their swelling pattern. Besides, we have also performed a comparison study on the effect of widely used foaming agents (NaHCO3 and Na2CO3) in the swelling kinetics and network properties of PEG crosslinked PMVE/MA hydrogels. The % swelling at 24 h for hydrogels with Na2CO3 was 3463%, significantly higher than hydrogels with NaHCO3 (1212%), suggesting the former as a better alternative for the delivery of macromolecular drugs. Besides, a slight increase in formulation pH and a decrease in the crosslinking temperature by 10 °C resulted in a significantly higher Seq% for the hydrogels. We also reported that the hydrogel exhibit significantly enhanced swelling characteristics in neutral and alkaline conditions compared to the acidic medium. These findings suggest that environmental factors such as pH and temperature and chemical factors such as the type of foaming agents strongly affect the swelling and network characteristics of PEG crosslinked PMVE/MA hydrogels. Therefore, these factors can be customised accordingly to regulate the release of therapeutics from PMVE/MA hydrogels as well as widen its application in biomedicine.

Effects of desensitizing dentifrices on dentin tubule occlusion and resistance to erosive challenges

BackgroundMany studies have demonstrated efficacy of casein phosphopeptide (CPP) containing products for dentin tubule occlusion for treatment of dentin sensitivity, but their effectiveness under dynamic erosive challenges remains to be elucidated. The purpose of the present study was to investigate the effectiveness of a desensitizing dentifrice containing CPP in occluding dentin tubules and resisting erosive challenges in comparison to that containing polyvinyl methyl ether/maleic acid (PVM/MA) copolymers.Methods A total of 33 dentin discs were prepared from coronal sections of human third molars and divided into 3 groups: a toothpaste containing CPP; a toothpaste containing PVM/MA and submicron silica; and a regular toothpaste (Controls). A soft-bristle toothbrush was used to brush the dentin discs with the dentifrices for 45 strokes in 30 s at a force of approximately 200 g. The brushing cycle was repeated after immersion of the dentin discs in artificial saliva overnight. The dentin discs were then challenged in orange juice for 10 min in an incubator rocking at 120 rpm. Three fields were randomly selected on each dentin disk surface to assess dentin tubule occlusions after each brushing cycle and after orange juice challenge with a 3D laser scanning microscope. Specimen cross sections were examined with a scanning electron microscope equipped with energy dispersive spectroscopy (SEM/EDS).ResultsAfter the first and second cycles of brushing, dentin tubules were occluded on average by 56.3% and 85.7% in CPP group, 66.2% and 88.1% in PVM/MA group, and 0.0 and 13.0% in the controls, respectively. There were no statistically significant differences in dentin tubule occlusions between the CPP and PVM/MA groups after two cycles of brushing (p>0.05). After dynamic erosive challenges with orange juice, 20.3% of the dentin tubules in the CPP group, 79.1% in the PVM/MA group and none in the control remained occluded (P<0.05). SEM/EDS imaging showed that dentin tubules were blocked with plugs containing dentifrice substances in CPP and PVM/MA groups after treatments, but none in the controls.ConclusionsDesensitizing dentifrices containing CPP or PVM/MA could effectively occlude dentin tubules after two cycles of brushing. PVM/MA in combination with submicron silicon dioxide exhibited stronger resistance to dynamic erosive challenges by acidic beverages. Inorganic fillers that can enter dentin tubules and resist erosive challenges may be key for desensitizing dentifrices.

The Effect of Various Milling Time Duration On The Characteristic of Glass Ionomer Cement (GIC) with The Addition of Liquid Pmve-Ma

A study entitled The Effect of Milling Time Duration on the Characteristics of Glass Ionomer Cement (GIC) Dental Cement with the Addition of Liquid PMVE-MA aims to determine the effect of milling time duration on the physical and mechanical properties of Glass Ionomer Cement, and to determine the optimum milling time duration in order to obtain GIC dental cement with the best characteristic to be applied as a dental restoration material. The duration of the milling time was 80 minutes, 90 minutes, 100 minutes, and 110 minutes. After the milling process, the next process was sintered at a temperature of 1200 for 1 hour to form Powder Glass Ionomer. Then Powder Glass Ionomer was added with Poly Methyl Vinyl Ether-Maleic Acid (PMVE-MA) to form a paste. The mixed paste was then formed. Sample characterization was the density test, the compressive strength test, and the vickers hardness test. The results of the density test obtained the highest value of 1.683 gram / cm3, the compressive strength test of 71.841 MPa, and the highest value of the hardness test of 92.3 Kg / mm2. These results increased as the increasing milling time duration up to 110 minutes.

Influence of γ-irradiation on mechanical behaviors of poly methyl-vinyl silicone rubber foams at different temperatures

In this study, the radiation dose effect of γ rays on the temperature-dependent mechanical behaviors of poly methyl-vinyl silicone rubber foams is investigated by uniaxial compression tests. After exposure to a wide radiation dose range from 0 to 500 kGy at room temperature, silicone rubber foams were tested at 10, 40, 70, and 100 °C. The test results show that temperature increase causes linear hardening for both unirradiated and irradiated samples due to the predominating entropy-related deformation of silicone rubber matrix. Moreover, increase of irradiation dose leads to linear hardening as a result of dominating cross-linking reactions of rubber networks. A stress hardening factor is introduced to characterize the effect of irradiation dose on temperature-related hardening behavior, which is defined as the ratio between the compressive stresses of irradiated and unirradiated samples for a given compression strain. The approximated constant stress hardening factor for each radiation dose condition implies that the irradiation dose does not affect the temperature-related hardening behavior. Based on the test findings, the Ogden Hyperfoam model was extended by correlating the initial shear modulus-related model parameters with radiation dose and temperature. The hardening exponent-related model parameters have been shown to be independent of radiation dose and temperature, and the Poisson's ratio-related model parameters are approximated to zero for the high porosity of the material. The prediction performance of the extended model is demonstrated by comparing the fitted model responses with test data over the studied irradiation doses and temperature range. The results are expected to be helpful for the safety evaluation of nuclear engineering structures.

Reusability, optimization, and adsorption studies of modified graphene oxide in the removal of Direct Red 81 using response surface methodology

In the present study, graphene oxide (GO) was synthesized by the oxidation of graphite powder using the Hummers method. The GO was polymerized with poly methyl vinyl ketone (PMVK) and aniline (GO-MVK-ANI). It was utilized as the effective adsorbent towards the removal of Direct Red 81 (DR 81) in aqueous solutions. Response surface methodology (RSM) was applied for optimization and adsorption studies of Direct Red 81 removal using GO-MVK-ANI. According to the RSM results, the effects of the main parameters (the adsorbent dose, contact time, and pH) in dye removal efficiency were investigated. The R2 value of 99.99% indicated that the predictions of the RSM model were acceptable for Direct Red 81 adsorption onto the adsorbent. The regeneration of GO-MVK-ANI for the dye adsorption showed fine efficacy in up to seven times of recyclability. The RSM model was used to evaluate the respective minimum and maximum values of 56.52% and 99.90% for the removal efficiencies of Direct Red 81.

On the use of aqueous solutions of polyvinyl methyl ether for the embolization of blood vessels

Aqueous solutions of polyvinyl methyl ether were investigated in order to test whether it is possible to utilize them as bases for embolic agents used to deliberately block blood vessels. This may be necessary in the course of treatment of vascular abnormalities, tumors, as well as during the preparation of patients for surgery. The right branch of the binodal curve for the binary system “polyvinyl methyl ether–water” was drawn using the cloud point method and the lower critical mixing temperature (35.5 °C) was calculated. Furthermore, the exact concentration of polyvinyl methyl ether in aqueous solutions at which phase transition occurs (given the temperature of 35.5 °C) was found to be 30 wt %. The viscosity–velocity curves for the 30% solution of polyvinyl methyl ether, obtained by rheoviscometry in the temperature range of 5 to 36 °C, indicate that this aqueous solution has a low viscosity and behaves like a Newtonian fluid. However, at the temperature of 35 °C and higher, close to the phase transition, a significant deviation from its Newtonian behavior is observed due to precipitation of polyvinyl methyl ether as it forms a solid white mass. Through the use of the Arrhenius–Frenkel–Eyring equation, the activation energy of the viscous flow for polyvinyl methyl ether solutions was found to be 31 kJ/mol. Based on refractometry data, it was demonstrated that phase transition in aqueous solutions of polyvinyl methyl ether is reversible. This feature can facilitate medical equipment cleaning before introducing the embolic agent into a patient’s bloodstream. Finally, the investigation determined some parameters, in which the formation of embolic agents from a 30% polyvinyl methyl ether aqueous solution occurs (in situ in a blood vessel at a temperature of 35.5 °C).

Remarkable performance improvement of copper phthalocyanine organic field-effect transistors with polymeric bilayer gate insulator

CuPc organic field-effect transistors (OFETs) were fabricated based on bilayer gate insulator consisting of polyvinyl alcohol (PVA) and methyl methacrylate co glycidyl methacrylate (P(MMA-GMA)). The complementary property of two polymer materials overcomes the drawbacks of each other, and then improves the dielectric properties of the composite insulator: a higher equivalent permittivity(k ~ 6.0), hydrophobicity, ultra-smooth (1.47 Å) and good compatibility with CuPc. The crystal quality of CuPc film have been improved effectively. As a result, a carrier mobility of 6.55 × 10−2 cm2/Vs and a threshold voltage of −3 V have been obtained. The Ids has increased double with the same insulator thickness.

Cerium oxide-catalyzed chemical vapor deposition grown carbon nanofibers for electrochemical detection of Pb(II) and Cu(II)

Chemical vapor deposition (CVD) grown cerium oxide catalyzed 1-D carbon nanofibers (Ce-CNFs) were synthesized first time via tip growth mechanism for the sensitive, selective and simultaneous determination of heavy metals/ions, i.e., Pb (II) and Cu (II). Acetylene and cerium oxide was used for growing the Ce-CNFs via CVD process as carbon source and catalyst for decomposing the acetylene respectively. Inexpensive polymethyl vinyl ether-alt-maleic anhydride (PMMVEA) was used as a binder rather than expensive Nafion solution. Ce-CNFs modified glassy carbon electrode was used as working electrode in three electrode assembly for simultaneous selective detection of Pb (II) and Cu (II) using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). The fabricated Ce-CNF electrode exhibited a linear behavior with Pb (II) and Cu (II), and the limit of detection was found to be 0.6 ppb and 0.3 ppb respectively. The electrode material was efficaciously tested against real water sample (Gomti river, Lucknow, India), for checking its practical applications. The prepared Ce-CNFs modified electrode is relatively nontoxic and low-cost. Consequently, it could be directly employed as a real-time electrochemical sensor for simultaneous determination of Pb (II) and Cu (II) ions.

Grafting of Polyacrylic Acid onto Thermo-Sensitive Polyvinyl Methyl Ether for Fluoxetine Extraction from Human Urine and Plasma

Grafting of Polyacrylic Acid onto Thermo-Sensitive Polyvinyl Methyl Ether for Fluoxetine Extraction from Human Urine and Plasma