Molecular Weight Of Polyvinylpyrrolidone Research Articles

The Influence of Polyvinylpyrrolidone Molecular Weight on the Structure and the Spectral and Nonlinear Optical Properties of Composite Materials with CdS/ZnS Nanoparticles

The influence of the molecular weight of polyvinylpyrrolidone on the structure and the spectral and nonlinear optical properties of composite materials (sols and coatings) containing CdS/ZnS nanoparticles is experimentally studied. Cd/ZnS nanoparticles were obtained by a liquid colloid-chemical method in the presence of polyvinylpyrrolidone. It is found that the size of polyvinylpyrrolidone molecules strongly affects the size of forming chalcogenide particles, as well as the structure and the spectral properties of mat-erials.

Controlling the drying process in vacuum foam drying under low vacuum conditions by inducing foaming by needle stimulation of the solution

Vacuum foam drying is a promising drying technique but an extremely high vacuum is needed to achieve “foaming.” The findings reported herein show that, when a solution is partially vacuum-dried to 0.05–2 g-solvent/g-dry matter (initial drying) and the solution is then punctured with a steel needle (needle stimulation), vacuum drying resumes as a result of the solution foaming, even under conditions of an insufficient vacuum (ca. 1,000 Pa) where foaming is minimal. Methanol, ethanol, and isopropanol were used as solvents, and sugar and different molecular weight polyvinylpyrrolidone were employed as solutes. The results indicate that needle puncturing introduces minute bubbles, which then triggers foaming.

Formulation, characterization and evaluation of mRNA-loaded dissolvable polymeric microneedles (RNApatch)

In this paper, we report a proof of concept study on the fabrication, characterization and therapeutic evaluation of in vitro transcribed messenger RNA (mRNA) loaded in a dissolving microneedle patch (RNApatch). We show that low molecular weight polyvinylpyrrolidone (PVP) can directly be used without further purification for RNApatch fabrication with no detectable mRNA degradation. Physical and functional integrity of mRNA stored within the RNApatch are completely preserved for at least 2 weeks under ambient conditions. While the loading of mRNA into RNApatch is limited by the solubility of mRNA in concentrated PVP solution, mechanical strength of RNApatch is not compromised by the presence of mRNA. RNApatch can mediate in vivo transgene expression of mRNA encoding luciferase for up to 72 hours and transfection efficiency and kinetics mediated by RNApatch compares favorably to subcutaneous injection. Interestingly, mRNA transfection efficiency does not correlate with contact surface area but instead increases with deeper delivery depths. In an E.G7-OVA immunotherapy model, RNApatch induces slightly higher cellular and humoral immune responses compared to subcutaneous injection. In conclusion, RNApatch is a viable delivery platform for mRNA and represents an attractive option with significant translation potential for the delivery of mRNA therapeutics.

Characterization of low-temperature solution-processed LiCoO2 thin-film cathode with molecular weight control of polyvinylpyrrolidone

Numerous LiCoO2 cathode thin-films have been prepared for all-solid-state thin-film battery applications. Preparation methods include sputtering, pulsed laser deposition, electron beam evaporation, screen printing, and spin coating. When compared to vacuum deposition methods, the solution-processed fabrication methods could result in significant cost savings and large-area production. Unfortunately, high-temperature annealing (Tanneal > 700 °C) of LiCoO2 cathode thin film is usually crucial for achieving a high performance layered phase. Here, we report on phase control of spin-coated LiCoO2 thin film by varying the molecular weight of polyvinylpyrrolidone (PVP) at low temperature. We could achieve thick and smooth film morphology by optimizing the PVP molecular weight. This method could be a promising cathode layer for low-cost thin-film batteries.

DEPENDENCE OF DISSOLUTION ENTHALPY OF POLYVINYLPYRROLIDONE IN WATER ON ITS INITIAL MOISTURE CONTENT

Changes in integral and differential enthalpies of dissolution of polyvinylpyrrolidone (PVP) of different molecular weight in water were determined as a function of initial moisture content of the polymer. Hydration numbers were calculated.

Synthesis of Cu Nanoparticles Using Copper Carbonate as Cu Source Toward Versatile Applications.

Cu nanoparticles (NPs) coated with polyvinylpyrrolidone (PVP) were fabricated by polyol method using copper carbonate as a raw material. To increase the reaction temperature, glycol multimers such as diethylene glycol, triethylene glycol, or tetraethylene glycol were examined as a solvent. With increasing degree of multimerization, average diameter of Cu NPs decreased. The synthesis of Cu NPs was further investigated by changing reaction temperature, the amount and molecular weight of PVP in triethylene glycol as a solvent. Average diameter and standard deviation of Cu NPs were found to be highly dependent on those factors. As a result, fine Cu NPs ranging from 28 to 67 nm in average size with narrow size distribution (standard deviation: 16-28%) were obtained. The obtained Cu NPs were applied to a nanofluid, which showed higher thermal conductivity than the theoretical value. The antibacterial activity of Cu NPs was also demonstrated, and found to have strong antibacterial activity.

One-pot rapid synthesis of high aspect ratio silver nanowires for transparent conductive electrodes

Silver nanowires (AgNWs) with high aspect ratio were rapidly one-pot synthesized by a polyol process in the presence of polyvinylpyrrolidone (PVP) as a stabilizer as well as the anisotropic agent, and the corresponding transparent conductive films were prepared by spin-coating method. The effects of PVP molecular weight and concentration on the morphology and aspect ratio of AgNWs were investigated in detail, and the optoelectrical properties of the transparent conductive films were briefly introduced. The presence of PVP induces the growth of silver directed to form high aspect-ratio nanowires by a high anisotropic mode. Appropriate PVP molecular weight and concentration allows the rapid synthesis of AgNWs with the diameter of about 78.2 nm, the length of 79.52 μm and the aspect ratio as high as 1009.2. The as-prepared AgNWs films possess a transmittance of 81.6% and a sheet resistance of 11.36 Ω/sq. The resultant AgNWs with high aspect ratio can be applied to prepare transparent conductive electrodes.

Effect of PVP Addition in the Preparation of Polyethersulfone (PES)–AgNO3 Antibacterial Membrane

Association of antibacterial agent into polymer–based material is an interesting, recent extension in membrane technologies research area. Asymmetric polyethersulfone–silver nitrate (PES–AgNO3) nanocomposite membranes were synthesized by wet phase inversion with polyvinylpyrrolidone (PVP) as additive. Three different molecular weights (MW) of PVP in the range of 10 K to 360 K were tested for their ability to stabilize and disperse silver in the polymer solution. Results showed that PVP 360 K plays a significant role in altering silver particle size with better dispersion compared to the membranes prepared without addition of PVP and with the addition of lower MW of PVP. Results agreed with the leaching detected by ICP–MS where silver loss during membrane fabrication for PES–Ag–P360 is only 0.4636 ppm (0.0093%). The antibacterial activity for the resultant membranes was tested using inhibition zone method. Results indicated that PES–AgNO3 and PES–AgNO3–PVP (loaded with only 0.5 wt% silver) were antibacterial to Escherichia coli and Staphylococcus aureus. The improvement of antibacterial properties of the prepared membranes could be primarily attributed to the PVP addition as well as the surface morphology and permeation properties.

Ultrasound-assisted interaction between chlorin-e6 and human serum albumin: pH dependence, singlet oxygen production, and formulation effect

The interaction between chlorin e6 (Ce6) and human serum albumin (HSA) in the presence and absence of ultrasound have been investigated by ultraviolet-visible absorption spectroscopy and fluorescence spectroscopy. Ce6 is found to bind strongly to HSA at or near physiological pH conditions, but the strength of the binding is significantly weakened at lower pHs. The intrinsic fluorescence of HSA is incrementally quenched with increasing concentration of Ce6, and the quenching is enhanced after exposure to high-frequency ultrasound. Our experimental results suggest that Ce6-induced sonodynamic oxidation of HSA is mainly mediated by singlet oxygen. The formulation of Ce6 by high molecular weight polyvinylpyrrolidone (PVP) increased its stability in aqueous solutions and its quantum yield of singlet oxygen under ultrasound irradiation.

Novel and simple method to synthesize donut-like TiO2 with photocatalytic activity

This paper presents a novel and simple method to fabricate donut-like TiO2 with efficient photocatalytic activity. Donut-like TiO2 was successfully prepared via electrospraying technique using a low molecular weight polyvinyl pyrrolidone (PVP) polymer. X-ray diffraction measurements show that donut-like TiO2 maintains a pure anatase structure. A transmission electron microscopy image reveals hollow donut-like TiO2. The effects of applied voltage parameter on energy gap, atomic force microscopy micrographs, field emission scanning electron microscopy pictures, and photoluminescence spectra are examined. The photocatalytic properties of donut-like TiO2 were evaluated with photocatalytic degradation of methylene blue (MB) in water under UV light irradiation. Donut-like TiO2 exhibits an efficient photocatalytic activity that reaches 67% after the degradation of MB in aqueous solution for 200min.

Effect of PVP on the synthesis of high-dispersion core–shell barium-titanate–polyvinylpyrrolidone nanoparticles

Monodispersed nanoparticles consisting of barium titanate (BaTiO3, BT) as the core and polyvinylpyrrolidone (PVP) as the shell were synthesized in a PVP-assisted low-temperature process in an aqueous solution at ambient pressure. In order to clarify the mechanism of this unique BT–PVP nanoparticle growth and the origin of the dispersion, the concentration and molecular weight of PVP used in the synthesis were varied, and the size and dispersion of the resulting nanoparticles in water were investigated by field-emission scanning electron microscopy and dynamic light scattering. Monodispersed nanoparticles with an average size of 130 nm were obtained by using an intermediate PVP concentration of 100 g/L and a PVP molecular weight of 10,000 g/mol. The thickness of the PVP shell was estimated by thermogravimetric analysis. For the highly dispersed BT–PVP, the thickness of PVP adsorbed on the BT surface was around 3–5 nm. Direct SEM observation of monodispersed BT–PVP in an aqueous solution using a unique sample holder was also demonstrated for the first time.

Photocatalytic degradation of polyvinylpyrrolidone in aqueous solution using TiO2/H2O2/UV system

ABSTRACTThe photocatalytic degradation of high molecular weight polyvinylpyrrolidone (PVP), a water-soluble polymer, using a TiO2/H2O2/UV system was studied in an annular photoreactor using a mercury vapor lamp (125 W) as the radiation source. The effect of the initial hydrogen peroxide concentration and the operating conditions, such as initial concentration of PVP, photocatalyst dosage and initial pH, on the reaction rate was also evaluated. It was observed that the efficiency of the TiO2/H2O2/UV system was 33% higher than that of a system without H2O2, reaching total organic carbon removals of above 80% in 6 h of reaction, depending on the experimental conditions. The optimal photocatalyst dosage was found to be 0.50 g L−1. Also, the results demonstrate that the reaction rate increases as the pH and initial concentration of PVP decrease. This treatment can be carried out successfully under optimal conditions and enhance the biodegradability of the organic matter remaining at the end of the application of the TiO2/H2O2/UV system, as assessed by biochemical oxygen demand/chemical oxygen demand measurements.

Continuous synthesis of PVP stabilized biocompatible gold nanoparticles with a controlled size using a 3D glass capillary microfluidic device

A reliable glass capillary microfluidic method was developed for a continuous production of well-controlled gold nanoparticles (AuNPs) capped with polyvinylpyrrolidone (PVP) of different molecular weights (PVP K15, PVP K30 and PVP K90). A two-phase co-flow glass capillary microfluidic device with an injection orifice diameter ranging between 100 and 240µm was used to synthesise 100–240µm was used to synthesise AuNPs via the chemical reduction between tetrachloroaurate trihydrate (HAuCl4·3H2O) and ascorbic acid. AuNPs with an average diameter between 48 and 135nm were synthesised, as determined by DLS measurements. Decreasing the injection orifice diameter, increasing the flow rate of ascorbic acid stream and its pH resulted in smaller AuNPs. The polydispersity index (PDI) was found to be independent on the injection orifice diameter or the molecular weight of PVP, but increased with the increase of flow rate and the pH of ascorbic acid stream. The stability study over 6-week period confirmed that PVP K30 with an average Mw of 40000g/mol was the best capping agent to synthesize and stabilise smaller AuNPs. The reactor fouling due to deposition of AuNPs on reactor walls and orifices was mitigated by hydrophobization of reactor/capillary walls with octadecyltrimethoxisilane and the use of ascorbic acid solution of higher pH.

Hierarchical Lotus Leaf-Like Mesoporous Silica Material with Unique Bilayer and Hollow Sandwich-Like Folds: Synthesis, Mechanism, and Applications

A facile and straightforward strategy was developed to synthesize hierarchical lotus leaf-like mesoporous silica material (LLMSM) with unique bilayer and hollow sandwich-like folds using hexadecylamine as a structure-directing agent, high molecular weight polyvinylpyrrolidone as a structure-stabilizing agent, and tetraethyl orthosilicate as a silica precursor in the mixed solvents of water and ethanol. The formation mechanism of LLMSM was proposed based on a series of experimental investigations. This new particulate platform exhibited superior adsorption capacity toward organic dye, effective catalytic reduction of 4-nitrophenol as a Ag catalyst supporter, and a multistage sustained drug release profile. Many other applications can be also envisaged for such a hierarchical structure.

Effect of the molecular weight of polyvinylpyrrolidone on the spectral properties of composite sols and coatings containing ZnS quantum dots

Effect of the molecular weight of polyvinylpyrrolidone on the spectral properties of composite sols and coatings containing ZnS quantum dots

Structural-thermochromic relationship of polydiacetylene (PDA)/polyvinylpyrrolidone (PVP) nanocomposites: Effects of PDA side chain length and PVP molecular weight

Abstract Reversible thermochromic polydiacetylene (PDA)/polyvinylpyrrolidone (PVP) nanocomposites are prepared by using 6 diacetylene (DA) monomers. The use of relatively low molecular weight (MW) PVP provides the nanocomposites with reversible thermochromism. The shortening of PDA alkyl tail causes the decrease of color-transition temperature, ranging from 75 to 85 °C. The shortening of alkyl segment adjacent to PDA carboxylic head group, however, does not provide the same trend. The nanocomposites constituting PDAs with 8, 6 and 4 methylene units exhibits color-transition at about the same temperature. The increase of PVP MW reduces the color-transition temperature and also affects thermochromic reversibilty of the PDA/PVP nanocomposites.

Network structure studies on γ–irradiated collagen–PVP superabsorbent hydrogels

Collagen–polyvinylpyrrolidone (PVP) superabsorbent hydrogels were synthesized by γ– irradiation in the absence of oxygen, using high molecular weight PVP and acidic collagen Type I. Sol–gel analysis and swelling experiments were performed in order to determine the gel fraction, network parameters, the yield of cross–linking, respectively scission, as well as to establish the diffusion characteristics of water. Rheological experiments and characterization of the chemical structure before and after irradiation were conducted in order to evaluate the gel character and its stability upon irradiation. The relationship between these parameters and radiation dose was also established. Gel fraction reached up to 90%, and the p0/q0 ratio (degradation vs. cross–linking ratio) shows a negligible degradation process. The collagen–PVP hydrogels present swelling in the range 1000–2000%, the diffusion exponent (n) was found to be between 0.59 and 0.68. The network parameters as the molecular weights between two successive cross−links (Mc), the cross–linking density (ϑe) and the mesh size (ξ) are ranged between 3.39–8.08×104g·mol–1, 1.24–2.95×10–5mol·cm–3, respectively 75–134nm.

Combined effects of hollow fiber fabrication conditions and casting mixture composition on the properties of polysulfone ultrafiltration membranes

ABSTRACTThis study is focused on identifying the combined effects of fabrication conditions and casting mixture composition on the properties of hollow fiber (HF) membranes. Three variables evaluated are air gap (0 and 2.5 cm); coagulation bath temperature (25°C; 35°C; 45°C) and molecular weight of polyvinylpyrrolidone (MWPVP = 10; 40; 65; 360; 1000 kDa). Prepared HF membranes were characterized in terms of specific permeate flux; surface morphology, charge and hydrophilicity; bovine serum albumin (BSA) rejection, Young modulus, and resistance to fouling by BSA. We illustrate that both higher and higher MWPVP are required to achieve optimal membrane morphology and performance.

A Rapid Assessment to Disperse Tailored Acetylene Blacks for the Battery Requiring a Few Amount of Conductive Agents

(Introduction) For recent lithium ion batteries(LiB) application, the demands for higher energy, higher power and longer life have been increasing. Therefore all chemical components in the LiB have been improved to meet the demands corresponding to various application. As for acetylene black(AB) it is one of the major conductive agents in the positive electrode. The smaller particle size ABs can make effective conductive paths for higher energy requiring a few amount of conductive agents(1,2. However, these smaller size ABs are difficult to be dispersed due to its high surface area and low interaction with NMP in the slurry. Even though oil absorption number(OAN) which is an evaluation method of aggregate in carbon blacks tends to be used as an index of the interaction with the solvent, the actual interaction with the solvent must be different from this classical evaluated results. Also, effects of dispersants which are often added in order to disperse AB homogeneously in the slurry cannot be evaluated with this index. In this research, we tried to acquire the exact information about actual interaction between the conductive agents and solvents like NMP with pulse NMR method. Then we defined the new index and researched the relationship between the index and practical properties for LiB application. (Experimental & Results) In the pulse NMR method, the relaxation time of NMP molecule which interacts with AB in the slurry is known to be shorter than of the NMP molecule not interacting(3. Therefore, we defined solvent interaction index(WAB) as the formula below. WAB=(Rav-Rb)/(Rb-SAB) Rav: The reciprocal of the relaxation time in the sample Rb: The reciprocal of the relaxation time in the blank(supernatant) SAB: Surface area of AB in the solvent Larger WABmeans higher solvent interaction between AB and NMP At first, four different specific surface areas of AB have been prepared and evaluated each solvent interaction index(WAB) with pulse NMR and the surface characteristics with desorption gas measurement (Fig.1). These results showed smaller particle size AB had lower solvent interaction index and there were associations between WAB and the amount of functional groups on the surface. That is to say, not only larger surface area but also low interaction with NMP(few functional groups) make smaller size AB difficult to be dispersed(4. AB4 was selected as a conductive agent and three different molecular weights of polyvinylpyrrolidone (PVP) , a major effective dispersant was prepared in this experiment. Then, four slurry samples were prepared by using a planetary centrifugal mixer and each solvent interaction index was evaluated with pulse NMR method (Fig.2). According to our results, PVP can improve solvent interaction between AB and NMP also larger molecular weight PVP showed better effect on the solvent interaction than the smaller one. This is because larger molecular weight PVP is thought to absorb the AB surface easier. In addition, slurry which have higher solvent interaction index shows low viscosity. Finally, in order to evaluate the effect of improved WABfor battery performance, we measured rate capability with AB4 and AB4+PVP samples (Fig.3). The mass was set to LCO:AB:PVdF=97.5:1:1.5 in the electrode. 3wt%(vs AB) of PVP was externally added into the electrode. This result showed battery containing AB4+ PVP 3wt% sample have good rate capability. Therefore, this pulse NMR method which can evaluate solvent interaction related to dispersibility is a useful tool to acquire the information for battery performance. In this presentation, further discussions about more detail results and other solvent interactions(Electrolyte etc.) will be presented. (Reference) (1)T. Saito, et al., 81th Electrochemical society of Japan, 2Q04, (2014). (2)Y. Nako, et al., 56th battery discussion, 3D13, (2015). (3) G.P. van der Beek, et al., Langmuir,Vol. 7, No.2 (1991). (4) T. Sonoda, et al., 42st Carbon material society, 1A09, (2015). Figure 1

Large-scale preparation of fernwort-like single-crystalline superstructures of CuSe as Fenton-like catalysts for dye decolorization

A simple green hydrothermal template-free method was developed to prepare single-crystalline superstructures of fern-wort-like copper selenide (CuSe) in large-scale by using polyvinylpyrrolidone (PVP) as both reductant and surfactant for the first time. Time-dependent morphologic evolution was made in order to explore the formation mechanism of the as-prepared product. The copper selenides with different morphologies, phases and structural forms could be prepared by varying the synthesis parameters, such as precursor molar ratios, precursor combinations, and the molecular weight of PVP. The fernwort-like superstructures of CuSe show excellent Fenton-like catalytic activities in degrading malachite green (MG) and rhodamine B (RhB). These catalysts play an important role in the degradation process of MG and RhB solution with the aid of H2O2 which can yield highly reactive hydroxyl radicals (HO·). Besides, the as-prepared CuSe catalyst is stable and reusable, thus it could be applied to the treatment of the dye contaminated waste water.