Molecular Weight Of Polyvinylpyrrolidone Research Articles

Insight into the Manipulation Mechanism of Polymorphic Transformation by Polymers: A Case of Cimetidine.

Employing polymer additives is an effective strategy to realize the manipulation of polymorphic transformation. However, the manipulation mechanism is still not clear, which limit the precise selection of polymeric excipients and the development of pharmaceutical formulations. The solubility of cimetidine (CIM) in acetonitrile/water mixtures were measured. And the polymorphic transformation from CIM form A to form B with the addition of different polymers was monitored by Raman spectroscopy. Furthermore, the manipulation effect of polymers was determined based on the results of experiments and molecular simulations. The solubility of form A is consistently higher than that of form B, which indicate that form B is the thermodynamically stable form within the examined temperature range. The presence of polyvinylpyrrolidone (PVP) of a shorter chain length could have a stronger inhibitory effect on the phase transformation process of metastable form, whereas polyethylene glycol (PEG) had almost no impact. The nucleation kinetics experiments and molecular dynamic simulation results showed that only PVP molecules could significantly decrease the nucleation rate of CIM, due to the ability of reducing solute molecular diffusion and solute-solute molecular interaction. A combination of crystal growth rate measurements and calculations of the interaction energies between PVP and the crystal faces of CIM indicate that smaller molecular weight PVP can suppress crystal growth more effectively. PVP K16-18 has more impact on the stabilization of CIM form A and inhibition of the phase transformation process. The manipulation mechanism of polymer additives in the polymorphic transformation of CIM was proposed.

Effects of polyvinylpyrrolidone additive on structures and properties of Poly(m-phenylene isophthalamide) hollow fiber membranes -experiment observation and computation approach

This study systematically investigates the effect of introduction of polyvinylpyrrolidone (PVP) used as a hydrophilic additive and its molecular weight change on the morphological, mechanical properties, and membrane performances of poly(m-phenylene isophthalamide) (PMIA) hollow fiber (HF) membranes prepared by dry-jet wet spinning method. The results of the morphological and mechanical properties clearly show an increased proportion of a sponge-like pore structure and an overall improvement in the mechanical properties of the PMIA HF membranes with higher molecular weight PVP, respectively. Interestingly, molecular dynamics simulation showed that the presence of PVP within the PMIA matrix activated the overall movement of PMIA molecules, suggesting that the overall flexibility of the system, which can potentially inhibit the collapse of relatively brittle membranes, is increased by the presence of PVP. Finally, as the molecular weight of PVP increases, a typical trade-off phenomenon is observed on PMIA HF membranes, where the water permeability decreases while the rejection rate increases. Based on these results, the findings on the influence of PVP additive and its potential as a reinforcing agent observed in this study through experimental analysis and computational approaches are expected to provide new insights into the development of high-performance polymeric HF membranes.

Miscibility of Amorphous Solid Dispersions: A Rheological and Solid-State NMR Spectroscopy Study

Miscibility is critical in the prediction of stability against crystallization of amorphous solid dispersions (ASDs) in the solid state. However, currently available approaches for its determination are limited by both theoretical and practical considerations. Recently, a rheological approach guided by the polymer overlap concentration (c*) has been proposed for miscibility quantification of ASDs [J. Pharm. Sci., 112 (2023) 204−212] and shown to be useful in predicting both accelerated and long term physical stability in the absence of moisture. However, this approach can only be performed at high temperatures (slightly above the melting temperature, Tm, of drugs), and little is known about the difference in miscibility between high and low temperatures (e.g., below the glass transition temperature, Tg). Here we compare the miscibility of nifedipine (NIF)/polyvinylpyrrolidone (PVP) ASDs as determined by the rheological approach at 175°C (∼3°C above Tm of NIF) and solid state NMR (ssNMR) 1H T1 and T1ρ relaxation times at -20°C (∼66°C below Tg of NIF). Our results indicate agreement between the two methods. For low molecular weight (Mw) PVP, T1ρ measurements are more consistent with the rheological approach, while T1 measurements are closer for relatively high Mw PVP. Our findings support the use of the c* based rheological approach for inferring miscibility of deeply cooled ASDs.

Features of the Formation of a Reinforcing Coating on Hydrogel Membranes Based on Polyvinylpyrrolidone Copolymers

This paper presents the study results of formation features of composite hydrogel/polyamide membranes obtained by modification of hydrogel films based on 2-hydroxyethylmethacrylate (HEMA) and polyvinylpyrrolidone (PVP) copolymers. The formation process of composite two-layer membranes was carried out in two stages: obtaining hydrogel membrane substrates followed by their modification with an ultra-thin layer based on a mixture of polyamide (PA) with PVP. The main task of the work was to investigate the possibility of forming a modifying PA/PVP coating on the surface of hydrogel films and to obtain composite hydrogel membranes with the required strength and osmotic permeability based on them. For the formation of composite two-layer membranes, PVP with MM = 12 × 103 g/mol and MM = 360 × 103 g/mol were used. Additional use of PVP in the modifying solution contributes to the process of its penetration into the hydrogel substrate. Together with the formation of a reinforcing layer, this ensures the obtainment of hydrogel films of increased strength, with the possibility of directional regulation of their diffusion permeability. It was found that the main factors affecting the nature of the interaction between the layers of the obtained composite films, as well as their physico-mechanical and sorption–diffusion properties, are the HEMA:PVP ratio in the original polymer–monomer composition (PMC), the formulation of the reinforcing layer, the duration of the modification process and the molecular weight of PVP in PMC and in the modifying solution. The strength and water content of two-layer composite hydrogel/polyamide membranes, as well as their salt and water permeability coefficients, are the highest in the case of using high-molecular weight PVP (MMPVP = 360 × 103 g/mol) and low-molecular weight (MMPVP = 12 × 103 g/mol) during the synthesis of the hydrogel substrate to obtain a PA-6/PVP solution for forming a reinforcing layer.

Technology for Biobanking of Epididymal Spermatozoa from Patient with Obstructive Azoospermia: Case Report about Baby Born after Conventional Freezing Only with a Nonpermeable Cryoprotectant 360 kDa Polyvinylpyrrolidone.

This publication reports, for the first time, the birth of a healthy child after intracytoplasmic sperm injection (ICSI) of motile spermatozoa after conventional ("slow") freezing of epididymal spermatozoa using 5% polyvinylpyrrolidone (PVP) of high molecular weight (360 kDa). Cryopreservation solution with 10% PVP was added to 30 µL of spermatozoa suspension in a 1:1 ratio, with a final PVP concentration of 5%. Then, polycarbonate capillaries for oocyte denudation with a diameter of 170 µm were filled with 60 µL of the resulting sperm suspension. After that, the capillaries were placed for 10 minutes at a height of 15 cm above liquid nitrogen and immersed into liquid nitrogen. To warm the spermatozoa, the capillaries were immersed in a water bath at a temperature of 40°C for 30 seconds. Oocyte fertilization was performed by ICSI. Zygotes were cultured in vitro for 5 days to the blastocyst stage. More than 100 spermatozoa were obtained after percutaneous epidydimal sperm aspiration, of which 80% were motile. After cryopreservation, storage for 3 months in liquid nitrogen, and thawing, 72% of the total sperm cells remained motile. Ten oocyte-cumulus complexes were found after follicle puncture, and eight metaphase II stage oocytes were fertilized using ICSI. After 18 hours, two pronuclei were found in seven (88%) of the oocytes. An analysis of the morphological characteristics of 5-day-old embryos showed that four (57%) of them reached the blastocyst stage. One embryo was transferred, and the remaining embryos were cryopreserved (vitrified). The onset of pregnancy was detected on the 14th day after embryo transfer, and one healthy girl (3300 g) was born at term.

Effect of PVP Molecular Weights on the Synthesis of Ultrasmall Cus Nanoflakes: Synthesis, Properties, and Potential Application for Phototheranostics.

Copper sulfide nanoparticles (CuS) hold tremendous potential for applications in photothermal therapy (PTT) and photoacoustic imaging (PAI). However, the conventional chemical coprecipitation method often leads to particle agglomeration issues. To overcome this challenge, we utilized polyvinylpyrrolidone (PVP) as a stabilizing agent, resulting in the synthesis of small PVP-CuS nanoparticles named PC10, PCK30, and PC40. Our study aimed to investigate how different molecular weights of PVP influence the nanoparticles' crystalline characteristics and essential properties, especially their photoacoustic and photothermal responses. While prior research on PVP-assisted CuS nanoparticles has been conducted, our study delves deeper into this area, providing insights into optical properties. Remarkably, all synthesized nanoparticles exhibited a crystalline structure, were smaller than 10 nm, and featured an absorbance peak at 1020 nm, indicating their robust photoacoustic and photothermal capabilities. Among these nanoparticles, PC10 emerged as the standout performer, displaying superior photoacoustic properties. Our photothermal experiments demonstrated significant temperature increases in all cases, with PC10 achieving an impressive efficiency of 51%. Moreover, cytotoxicity assays revealed the nanoparticles' compatibility with cells, coupled with an enhanced incidence of apoptosis compared to necrosis. These findings underscore the promising potential of PVP-stabilized CuS nanoparticles for advanced cancer theranostics.

Three-dimensionally printable hollow silica nanoparticles for subambient passive cooling

Abstract Solar reflectance and thermal emissivity are critical benchmarks for evaluating the effectiveness of passive cooling strategies. The integration of three-dimensional (3D) printing techniques with passive cooling materials enables local thermal management of multifaceted objects, offering opportunities for unexplored energy-saving applications. For example, conformal printing of cooling materials can mitigate solar absorption caused by the top metal electrodes in solar cells, thereby improving their efficiency and lifetime. In this study, we report the synthesis of 3D printable hollow silica nanoparticles (HSNPs) designed to induce subambient cooling performance under daylight conditions. HSNPs with diameters of 400–700 nm and silica shell thicknesses of approximately 100 nm were synthesized using an in-situ sol–gel emulsion method. Subsequently, these HSNPs were formulated into printable pastes by carefully selecting the mixture concentration and molecular weight of polyvinylpyrrolidone (PVP). The PVP-linked HSNPs exhibited a solar (0.3–2.5 μm) reflectivity of 0.98 and a thermal (8–13 μm) emissivity of 0.93. In contrast to a single silica nanoparticle (NP), the scattering analysis of a single HSNP revealed a distinctive scattering distribution characterized by amplified backward scattering and suppressed forward scattering. In outdoor daytime experiments, the HSNP-printed sample led to the subambient cooling of a dielectric substrate, surpassing the cooling performance of reference materials such as silica NPs, silver pastes, and commercial white plastics and paints.

Fabrication and optimization of PES/PVP hollow fiber membranes using Box–Behnken model and CART algorithm

AbstractThis study focuses on the optimization of polyethersulfone (PES) hollow fiber membranes fabricated with the phase inversion method. A Box–Behnken experimental design was employed with three different PES concentration ratios (11, 14, 17 wt.%), three polyvinylpyrrolidone (PVP) molecular weight ratios (K30/K90 ratios of 6:0, 3:3, 0:6 wt.%), three different bore fluid (BF) composition ratios (water/alcohol ratios of 20:80, 60:40, 100:0), and three different air gap values (24, 37, and 50 cm). The results were analyzed in terms of pure water permeability (PWP) and porosity as optimization parameters using response surface methodology and the classification and regression tree (CART) model. ANOVA results revealed significant effects of PES concentration, PVP molecular weight, and BF composition on the outcomes. After optimization, the maximum PWP and the maximum porosity were obtained as 360.15 L/m2 h bar, 60.57%, respectively. The CART model achieved sufficient accuracy in classifying samples.

Measurements, correlations and thermodynamic modeling of aqueous two-phase systems of polyvinylpyrrolidone (PVP) + sulfate/citrate salts

Aqueous two-phase systems (ATPS) can be described as an alternative to traditional liquid-liquid extraction systems, typically consisting of a polymer and a salt solution. An alternative polymer called polyvinylpyrrolidone (PVP) has emerged as a viable option for ATPS due to its low cost, stability, and potential. This study aimed to investigate the effect of the molecular weight of poly (vinylpyrrolidone) (PVP) (K17, K25, and K30) and the temperature (298.15, 303.15, and 308.15 K) in the system ATPSs composed of PVPs and sodium sulfate/potassium sulfate/tri sodium citrate. The tie-line data were determined by measuring the density (ρ) and refractive index (nD). Moreover, the phase compositions and plait point are investigated for different PVPs molecular weight, temperature, and salt type. In addition, the effect of these parameters on the binodal curve, tie-line length (TLL), and slope of tie line (STL) are analyzed in detail by comparing them with the literature data. The impact of the parameters on the binodal curves was investigated by utilizing the values of the effective excluded volume parameter (EEV) that were calculated from the LLE data. Furthermore, the binodal curves and the tie-line compositions were well-fitted by using some semi-empirical equations. The phase separation ability is enhanced with temperature and PVPs molecular weight. The modified UNIFAC-NRF is used to correlate the liquid-liquid equilibrium data of the studied systems and the optimized binary group interaction parameters were determined.

Towards Optimizing Surface Coverage for PVP-Assisted PZT Ferroelectric Thick Film

130,000 g/mol molecular weight of polyvinylpyrrolidone (PVP) was purposed to prepare PZT sol desiring the thick film (≥1.0 µm) deposition on Pt(111)/TiO2/SiO2/Si. Centrifugal force and the spilling of sol during spin coating were found to control the cracks and surface coverage of the films. A rotation-dependent typical pattern formation at the central part of the substrate was observed and better coverage was observed on gel drying 60 °C than 125 °C. Though the remnant polarization (2Pr) of 21.4 µC/cm2 was recorded at 100 Hz for 2.1 µm, it is 41.8 µC/cm2 for 1.06 µm thick films.

The Exploration of Ink Formulations in Binder Jet 3D Printing Drugs.

The application of binder jet 3D printing technology in the pharmaceutical field is developing rapidly. The properties of the ink are very important, affecting the stability of the ejection and the precision of the finished product, but there is a great lack of research on pharmaceutical inks. This study used solvents and excipients commonly used in pharmaceuticals to quantify the printability of inks using printability Z value theory, while using an ink-jet printing and observation platform to analyze the droplet ejection state of different composition inks from microscopic level. Studies have shown that compared to ethanol, the ejection effect of droplets was better when isopropanol was added to the ink, and the proportion added should not be greater than 40%; as the molecular weight of polyvinylpyrrolidone (PVP) increased, the concentration of PVP tolerated by the ink decreased; glycerin has a high ejection efficiency when the proportion is within 10%. In summary, a superior ink formulation of 40% aqueous isopropanol plus 0.1% PVP K30 and 4% glycerin was obtained. With this ink, levetiracetam dispersible tablets were prepared with a smooth printing process and the tablets had good appearance, good mechanical properties, and rapid release. This study provides a mutual validation of the Z value theory and the results of droplet ejection and tablet printing, while providing good ideas.

Influence of polyvinylpyrrolidone (PVP) in the synthesis of luminescent NaYF4:Yb,Er upconversion nanoparticles

Polyvinylpyrrolidone (PVP) can be used to produce upconversion nanoparticles (UCNPs) in an advantageous manner, i.e. at modest temperatures in open-to-air conditions with simple hotplate and flask apparatus. However, the influence of PVP parameters on the formation of UCNPs has not been previously investigated. In this exploratory study, we establish that PVP molecular weight and relative amount of PVP can greatly influence the morphology and diameter of NaYF4:Yb,Er UCNPs produced via the PVP-assisted route. At nominal amounts of PVP, varying the molecular weight of PVP in synthesis between 10,000 g mol−1 (PVP10), 40,000 g mol−1 (PVP40), and 55,000 g mol−1 (PVP55), had minimal effect on UCNP morphology, whereas reducing the quantity of PVP10 and PVP40 in the reaction to 10% of the nominal amount resulted in two notable effects: (1) the generation of a greater range of UCNP diameters and (2) the production of an unexpected sub-population of rhombus-shaped UCNPs. Bulk and individual nanoparticle analysis indicates that all UCNP morphologies were cubic (α-phase) crystal structure and consisted of NaYF4:Yb,Er. Optical emission properties exhibited only modest green and red luminescence emission ratio when PVP parameters were varied. However, separately produced PVP40 NaYF4:Yb,Tm UCNPs exhibited a much more intense and dual-band blue/red emission. This exploratory work demonstrates that tailoring PVP content in synthesis of UCNPs can greatly alter morphology of UCNPs produced and should be carefully considered in experimental design. However, the underlying mechanisms of action of the role PVP plays in this synthesis remain unclear. Ultimately, significant further work is still required to fully elucidate the relevant chemistry to achieve full control of PVP-UCNP synthesis.

Influence of Polyvinylpyrrolidone Molecular Weight and Concentration on the Precipitation Inhibition of Supersaturated Solutions of Poorly Soluble Drugs.

Supersaturating drug delivery systems such as solid dispersions of a drug in a polymer are frequently used in pharmaceutical development to enable oral delivery of poorly soluble drugs. In this study, the influence of the concentration and molecular weight of polyvinylpyrrolidone (PVP) on the precipitation inhibition of the poorly soluble drugs albendazole, ketoconazole and tadalafil is investigated to expand the understanding of the mechanism of PVP as a polymeric precipitation inhibitor. A three-level full-factorial design was used to delineate the influence of polymer concentration and viscosity of the dissolution medium on precipitation inhibition. Solutions of PVP K15, K30, K60 or K120 at concentrations of 0.1, 0.5 and 1% (w/v), as well as isoviscous solutions of PVP of increasing molecular weight, were prepared. Supersaturation of the three model drugs was induced by the use of a solvent-shift method. Precipitation of the three model drugs from supersaturated solutions in the absence and presence of polymer was investigated by the use of a solvent-shift method. Time-concentration profiles of the respective drugs in the absence and presence of polymer pre-dissolved in the dissolution medium were obtained by the use of a μDISS Profiler™ to determine the onset of nucleation and the precipitation rate. Multiple linear regression was used to evaluate the hypothesis that precipitation inhibition is influenced by the PVP concentration (i.e., the number of repeat units of the polymer) and the medium viscosity of the polymer for the three model drugs. This study showed that an increased concentration of PVP (i.e., an increased concentration of the PVP repeat units, independent of the molecular weight of the polymer) in solution increased the onset of nucleation and decreased the precipitation rate of the respective drugs during supersaturation, which can be explained by an increase in molecular interactions between the drug and polymer with increasing concentrations of polymer. In contrast, the medium viscosity had no significant influence on the onset of the nucleation and precipitation rate of the drugs, which can be explained by solution viscosity having a negligible effect on the rate of drug diffusion from bulk solution to the crystal nuclei. In conclusion, the precipitation inhibition of the respective drugs is influenced by the concentration of PVP, i.e., by molecular interactions between the drug and polymer. In contrast, the molecular mobility of the drug in solution, i.e., the medium viscosity, has no influence on the precipitation inhibition of the drugs.

Effect of molecular weight and content of polyvinylpyrrolidone on cell proliferation, loading capacity and properties of electrospun green tea essential oil-incorporated polyamide-6/polyvinylpyrrolidone nanofibers

Electrospun nanofibers demonstrate a novel category of materials that display great potential in numerous biomedical applications including tissue engineering, drug delivery, regenerative medicine, and wound healing. Here, composite nanofibrous scaffolds of polyamide-6 (PA-6), polyvinylpyrrolidone (PVP), and tea tree oil (TTO) was fabricated by electrospinning method and the effect of various molecular weight of PVP on properties of produced fiber scaffolds was studied. The investigations showed that the increase in the molecular weight of PVP, as well as the decrease in its content provides the thinner fibers (220.90 ± 59.0 nm) with higher porosity (∼90%), high water vapor transmission rate (WVTR) (3945. g/m2.24 h), and low surface wettability (∼85°). The morphological investigation accomplished with scanning electron microscope (SEM) showed the uniform bead-free electrospun fibers scaffold. The structural characteristics of the produced scaffolds were investigated with Fourier Transform Infrared Spectroscopy (FTIR). The results of the mechanical test of the produced fibers confirmed their ability to protect the wound area against external forces during the healing process. Antibacterial and antioxidant tests of samples containing TTO showed excellent and strong activities. Besides, the in vitro cytotoxicity, and cell adhesion was evaluated, that the obtained results illustrated that the electrospun fibers were biocompatible and supported cell adhesion. Based on the findings, this new electrospun matrix is expected to be effective as a potential wound dressing for skin regeneration.

A Novel One-Pot Synthesis of PVP-Coated Iron Oxide Nanoparticles as Biocompatible Contrast Agents for Enhanced T2-Weighted MRI

A contrast agent with specific characteristics is essential for high-quality magnetic resonance imaging (MRI). It plays a crucial role in enhancing the visibility of certain tissues and structures, making it imperative for diagnostic procedures. Superparamagnetic iron oxide nanoparticles (SPIONs) have emerged as a promising alternative to traditional contrast agents for MRI due to their non-toxicity and superior magnetic properties. However, a suitable surface coating strategy is needed to produce polymer-coated SPIONs with controllable sizes in order to enhance their stability and biocompatibility. This study presents a novel one-pot synthesis method for the production of highly stable polyvinylpyrrolidone (PVP)-coated SPIONs. By systematically manipulating the physicochemical properties of SPIONs, the effect of different molecular weights of PVP was studied. The results showed that SPIONs coated with PVP with molecular wight 40,000 g/mol (40 K) exhibited a high magnetization (Ms = 48.4 emu/g), an average size distribution (11.61 nm), and excellent stability. The relaxivity of coated and uncoated SPIONs was investigated using MRI images. The results revealed that the (r2/r1) ratio of PVP40K-SPIONs was 72.55, compared to 55.72 for the bare SPIONs, making them a highly promising T2-contrast agent for future development of MRI applications. This study opens new avenues for the development of biocompatible and stable SPIONs for improved medical diagnostic and imaging.

ВПЛИВ МОЛЕКУЛЯРНОЇ МАСИ ПОЛІВІНІЛПІРОЛІДОНУ НА СОРБЦІЙНІ ТА ФІЗИКО-МЕХАНІЧНІ ВЛАСТИВОСТІ ГІДРОГЕЛЬ/ПОЛІКАПРОАМІДНИХ ДВОШАРОВИХ МЕМБРАН

The paper presents the study results of the molecular weight effect of polyvinylpyrrolidone (PVP) on the properties of composite hydrogels/polycaproamide membranes, which were obtained by modifying hydrogel films based on copolymers of 2-hydroxyethylmethacrylate (HEMA) with PVP by applying ultra- thin layers on the basis of a polyamide (PA-6) with PVP mixture. It was found that the interaction magnitude between the layers of composite membranes, as well as their properties – water content, tensile strength, salt and water permeability coefficients, largely depend on the molecular weight of PVP as in the original polymer-monomer composition and in the modifying PA-6/PVP solution.

Effect of Polyvinylpyrrolidone Molecular Weight on the Synthesis of Silver Nanoparticles using a Polyol Method

Nanoparticles possess a great interest for researchers because of their unique physicochemical properties and their various applications. Polyol synthesis is a kind of synthesis that can produce silver nanoparticles. It has been known that the molecular weight of polyvinylpyrrolidone (PVP) can influence the size and shape of the nanoparticles produced. This research used a polyol synthesis to fabricate silver nanoparticles in which AgNO3, PVPMW= 55,000 and PVPMW= 360,000, ethylene glycol (EG) and natrium bromide (NaBr) were used as precursor, capping agent and additives respectively. The synthesis was carried out at 60 and 100 °C. The silver nanoparticles were characterized using Ultraviolet-visible (UV-Vis) spectrophotometer, Transmission Electron Microscopy (TEM) and X-Ray Diffraction (XRD). The UV-Vis spectrum showed the presence of AgNPs peak between 400-500 nm. The AgNPs synthesized using PVPMW=55,000 produce a higher absorbance spectrum than PVPMW=360,000. The TEM image confirmed the size and shape of AgNPs from using PVPMW= 55,000 showing sphere and anisotropic shape. This result proved the role of oxidative etching caused by the addition of NaBr which affects the form of AgNPs. In addition, the XRD results showed typical crystalline peaks of AgBr and Ag.

Effect of melt shearing on d-mannitol crystal twisting in the presence of small molecule and macromolecular additives

Many molecular crystals grow as twisted lamellae from the melt when the driving force is high, but the mechanisms governing the spontaneous formation of helicoidal crystallites are varied and those operative in particular cases are difficult to identify. Polyvinylpyrrolidone (PVP) induces the crystallization of d-mannitol as banded spherulites comprised of twisted fibrils emanating radially from spherulite nucleation centers. The molecular weight of the PVP phase affects the twisting pitch, P, (rotation of the crystallite by 180°), in d-mannitol thin films crystallized from the melt. At a relatively high crystallization temperature (Tc = 130 °C), P was sensitive to the PVP molecular weight, ranging from 390 ± 20 μm for d-mannitol films incorporating 15 wt% 10 kDa PVP to 20 ± 3 μm for the same weight of 1300 kDa PVP. Magnitudes of complex viscosities, η∗, of d-mannitol/PVP melts measured via small-amplitude oscillatory shearing were strongly dependent on the PVP molecular weight, but were not correlated to P(T). Instead, P was sensitive to the dynamic PVP chain conformation during d-mannitol crystallization. Under steady torsional shear, P decreased from ∼ 30 μm to ∼ 8 μm with increasing shear rates from 0.01 to 100 s−1 for d-mannitol films crystallized at 130 °C in the presence of 15 wt% 10 or 1300 kDa PVP. Shear forces decrease the entanglement density of polymer chains while orienting the chains along the stream lines of the viscometric flow, indicating that the conformations of macromolecular additives can affect the pitch of banded spherulites. By contrast, P in d-mannitol twisted by d-sorbitol was independent of shear rate.

Acid-triggered polyether sulfone - Polyvinyl pyrrolidone blend anion exchange membranes for the recovery of titania waste acid via diffusion dialysis

Dense PES (polyether sulfone) - PVP (polyvinyl pyrrolidone) blend membranes are proposed to recover titania waste acid by diffusion dialysis. These dense membranes can simply be prepared by the solution casting method, and the spontaneous quaternization of the N and O atoms in pyrrolidone with H+ in sulfuric acid solution turns them into effective anion exchange membranes very suitable for the fractionation of sulfuric acid/sulfate. In this work, the influence of the PVP molecular weight (K30 and K90), the composition of the casting solution and the concentration of sulfuric acid in the post-treatment step on the physicochemical properties and mass transfer performance of the membranes are systematically investigated. It is found that the content of absorbed sulfuric acid in the dense membranes increases with the increasing PVP content (20–60 wt%) in the membranes, after the equilibration in 2.68 M H2SO4. The content of H+ in blend membranes with PVP K30 (K30 series) is 0–5.73 mmol/(g dry membrane), while that in the membranes with PVP K90 (K90 series) is 0–5.34 mmol/(g dry membrane). The permeability coefficients of H2SO4 and FeSO4 in the K30 and the K90 series membranes also increase gradually, ranging from 0–200 × 10−9 m2/h and 0–8.81 × 10−9 m2/h, respectively. The largest selectivity coefficient of H2SO4/FeSO4 can reach 1800. The permeability coefficients of H2SO4 and FeSO4 also increase gradually with the increase of the solution acid concentration, and the selectivity remains excellent. These PES-PVP dense membranes show very good chemical stability, the permeability coefficients of H2SO4 and FeSO4 for a blend membrane with 55 wt% PVP K30 remain unchanged in a 2.68 M H2SO4 solution for 337 days. This study would provide valuable guidance for the application of these PES-PVP blend anion exchange membranes in the recovery of titania waste acid by diffusion dialysis.

In‐situ Synthesis of CsPbBr 3 Nanocrystals/Polyvinyl Pyrrolidone Ethanol Sol and High Resolution Fingerprint Identification

This article provides a remarkably simple strategy to successfully prepare CsPbBr3 nanocrystals/ethanol sol with relatively high stability by the synergistic effect of polyvinylpyrrolidone and trace water. By adding alcohol-soluble thermoplastic acrylic resin, the fingerprint identification films can be simply and quickly prepared, which can clearly emerge the three-level structure of fingerprint.