High Molecular Weight Polyvinylpyrrolidone Research Articles

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.

Polyvinylpyrrolidone – KNNLST lead-free ceramic composites for dielectric applications

Piezoelectric composites offer many advantages compared to piezoelectric ceramics or polymers because of their mechanical flexibility and relatively high stress-induced voltage. In this research, high-molecular weight polyvinylpyrrolidone (PVP) and lead-free piezoelectric (K0.45Na0.51Li0.04) (Nb0.85Ta0.1Sb0.05)O3 (KNNLST) ceramics have been used to produce composites. The possible range of composites from 0 to 100 wt% has been explored. The ceramics were produced using conventional processing methods, while the composites were solution-cast after being mixed with a magnetic stirrer. The composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and dielectric and piezoelectric characterization to determine their properties. The morphology of the composites indicates the homogeneous distribution of the ceramics in the polymer. The XRD patterns show that the dissolved amorphous PVP precipitates and the addition of KNNLST ceramics contributes substantially to the crystalline phase formation. The relative permittivity and loss tangent values increase with an increase in ceramic content. Acceptable polarization and strain hysteresis curves were obtained only for the KNNLST ceramics. The composites produced will be suitable for dielectric applications.

The structural and figure of merit photodetector of PVP-doped with lanthanum

This study describes the fabrication and characterization of PVP and PVP/La thin films from a mixture of high molecular weight polyvinylpyrrolidone (PVP) and (1, 2, and 3)% lanthanum chloride using an electrospinning process on glass and silicon. It includes an N- type (Si) (111) substrate at room temperature. Field Emission Scanning Electron Microscopy (FESEM) analysis reveals fibers with an average diameter in the range of 125-250 nm. The mean fiber diameter decreases with increasing concentration (La). The optical energy gap was determined from the analysis of the transmission spectrum in the UV-visible region. The optical gap (Eg) gradually decreases from 4 eV to 3.64 eV for undoped PVP films due to the increase in La ion content at 3%, which determines the feasibility of using these obtained fibers in the manufacturing process. PVP/La nanofibers as detectors.

Chronic Kidney Disease from Polyvinylpyrrolidone Deposition in Persons with Intravenous Drug Use.

Persons with intravenous drug use have a higher risk of developing CKD compared with the general population. In Norway, deposits of polyvinylpyrrolidone have been observed in kidney biopsies taken from persons with opioid addiction and intravenous drug use since 2009. Polyvinylpyrrolidone is an excipient commonly used in pharmaceuticals, and the polyvinylpyrrolidone deposits observed in these patients were caused by intravenous injection of a specific oral methadone syrup containing very high molecular weight polyvinylpyrrolidone. Here, we present the clinicopathologic findings from 28 patients with CKD associated with polyvinylpyrrolidone deposition in the kidney. The 28 patients and their kidney biopsies were included when polyvinylpyrrolidone deposition was recognized, either retrospectively or at the time of diagnostic evaluation. Biopsies were taken between 2009 and 2016. We collected laboratory parameters and clinical data from digital patient charts. For each kidney biopsy, the glomerular volume, extent of polyvinylpyrrolidone deposition, and tubulointerstitial area with tubular atrophy were assessed quantitatively. All patients (mean age: 37 years) had CKD (mean eGFR: 33 ml/min per 1.73 m2) and normal urine protein or non-nephrotic-range proteinuria. Biopsies showed moderate to severe tubular atrophy (mean extent: 65%) and interstitial infiltrates of vacuolated macrophages containing polyvinylpyrrolidone (mean share of biopsy area: 1.5%). Underperfused and ischemic glomeruli were common findings. In 22 samples, ultrastructural investigation revealed polyvinylpyrrolidone-containing vacuoles in the mesangial or endothelial cells of glomeruli. At the last follow-up, most patients had stable or improved eGFR. Two patients had developed kidney failure and underwent hemodialysis. Intravenous injection of a specific oral methadone syrup caused polyvinylpyrrolidone deposition in the kidney in persons with opioid addiction and intravenous drug use. Kidney biopsy findings suggested an association between polyvinylpyrrolidone deposition and tubular atrophy.

Production and qualification of an electrospun ceramic nanofiber material as a candidate future high power target

In an effort to develop and design next generation high power target materials for particle physics research, the possibility of fabricating nonwoven metallic or ceramic nanofibers by electrospinning process is explored. A low-cost electrospinning unit is set up for in-house production of various ceramic nanofibers. Yttria-stabilized zirconia nanofibers are successfully fabricated by electrospinning a mixture of zirconium carbonate with high-molecular weight polyvinylpyrrolidone polymer solution. Some of the inherent weaknesses of electrospinning process like thickness of nanofiber mat and slow production rate are overcome by modifying certain parts of electrospinning system and their arrangements to get thicker nanofiber mats of millimeter order at a faster rate. Continuous long nanofibers of about hundred nanometers in diameter are produced and subsequently heat treated to get rid of polymer and allow crystallize zirconia. Specimens were prepared to meet certain minimum physical properties such as thickness, structural integrity, thermal stability, and flexibility. An easy innovative technique based on atomic force microscopy was employed for evaluating mechanical properties of single nanofiber, which were found to be comparable to bulk zirconia. Nanofibers were tested for their high-temperature resistance using an electron beam. It showed resistance to radiation damage when irradiated with 1 MeV ${\mathrm{Kr}}^{2++}$ ion. Some zirconia nanofibers were also tested under high-intensity pulsed proton beam and maintained their structural integrity. This study shows for the first time that a ceramic nanofiber has been tested under different beams and irradiation condition to qualify their physical properties for practical use as accelerator targets. Advantages and challenges of such nanofibers as potential future targets over bulk material targets are discussed.

Optical Oxygen Sensor Patch Printed with Polystyrene Microparticles-based Ink on Flexible Substrate.

Optical oxygen sensors based on photoluminescence quenching have gained increasing attention as a superior method for continuous monitoring of oxygen in a growing number of applications. A simple and low-cost fabrication technique was developed to produce sensor arrays capable of two-dimensional oxygen tension measurement. Sensor patches were printed on polyvinylidene chloride film using an oxygen-sensitive ink cocktail, prepared by immobilizing Pt(II) mesotetra(pentafluorophenyl)porphine (PtTFPP) in monodispersed polystyrene microparticles. The dispersion media of the ink cocktail, high molecular weight polyvinyl pyrrolidone suspended in 50% ethanol (v/v in water), allowed adhesion promotion and compatibility with most common polymeric substrates. Ink phosphorescence intensity was found to vary primarily with fluorophore concentration and to a lesser extent with polystyrene particle size. The sensor performance was investigated as a function of oxygen concentrations employing two different techniques: a multi-frequency phase fluorometer and smart phone-based image acquisition. The printed sensor patch showed fast and repetitive response over 0-21% oxygen concentrations with high linearity (with R2 >0.99) in a Stern-Volmer plot, and sensitivity of I0/I21 >1.55. The optical sensor response on a surface was investigated further using two-dimensional images which were captured and analyzed under different oxygen environment. Printed sensor patch along with imaging read-out technique make an ideal platform for early detection of surface wounds associated with tissue oxygen.

Выбор спейсера на первом этапе лечения поздней глубокой перипротезной инфекции тазобедренного сустава

Abstract. Introduction Periprosthetic infection in hip arthroplasty is a social and economic problem. Its main reason is multidrug resistance of microorganisms. Purpose To evaluate the effectiveness of the first stage in two-stage revision arthroplasty for the treatment of deep periprosthetic infection of the hip joint by improving the constructive and antibacterial features of spacers. Materials and methods The treatment results of 127 patients with late deep periprosthetic hip joint infection who underwent two-stage revision arthroplasty in the period from 2015 to 2019 were analyzed. In the first group, 42 patients were fitted with a two-component (total) spacer based on the developed antimicrobial composition of bone cement with gentamicin, antiseptics and polymer (patent RU 191236). In the second group, a two-component spacer (patent RU 174697) based on conventional bone cement with gentamicin was implanted in 43 patients; the third group of 42 patients had a preformed spacer. Results A bactericidal and antiadhesive, nontoxic composition based on bone cement with gentamicin with antiseptics poviargol, dioxidine and high molecular weight polyvinylpyrrolidone with a prolonged action for 348 days against gentamicin-resistant staphylococci has been developed. All patients underwent the first stage of hip arthroplasty with removal of the implant and installation of a spacer. Recurrence of periprosthetic infection was observed in 1 (2.3 %) patient of the first group, in 5 (11.6 %) in the second and in 6 (14.2 %) patients of the third group. Non-infectious complications such as spacer dislocation and instability were observed in 12 cases, one case (2.3 %) in the first, 2 (4.6 %) in the second and 9 (21.4 %) in the third group. The average time from the first stage of treatment to the second stage of re-implantation was 7.5 months (range, 4–13 months). Discussion According to the literature, the introduction of new antibiotics into the bone cement with gentamicin does not increase the antimicrobial action of the spacer, especially against antibiotic-resistant isolates, and the use of a preformed spacer contributes to an increase in the number of non-infectious complications. Antiseptics with different mechanisms of action are able to act on antibiotic-resistant bacteria, and the polymer can prolong this effect. Conclusions Creation of two-component spacers based on bone cement with gentamicin using antiseptics with different mechanisms of action and polymer promotes long-term bactericidal action of the spacer, which leads to effective sanation of the joint area, reducing non-infectious complications.

Preparation and characterization of asymmetric hollow fiber polyvinyl chloride (PVC) membrane for forward osmosis application

• Asymmetric nanofiltration PVC hollow fiber membranes were fabricated via dry-wet spinning technique. • Delayed demixing was achieved by addition of high molecular weigh PVP. • Volatile solvent evaporation resulted in dense selective layer. • The effect of fabrication parameters were investigated in order to introduce best-suited membrane. • The effect of DS concentration and temperature were studied by means of Flux and SRSF. PVC hollow fiber (HF) membrane for forward osmosis (FO) application as a potential candidate for water desalination was fabricated by altering the spinning conditions. High molecular weight polyvinylpyrrolidone (PVP) was used as a blending additive to control the phase inversion process by increasing viscosity leading to delayed demixing as observed on the ternary phase diagram and confirmed by the simulation results, and forming dense barrier layer structure by providing chain entanglements with the PVC matrix. PVP/PVC ratio of 5/100 was proved to offer suited membrane morphology and selective layer. Different air gap distances and bore fluid flow rates were investigated to achieve proper fabrication parameters. The prepared membranes presented high flux and salt rejection in nanofiltration (NF) and FO tests. The best-suited membrane demonstrated the structural parameter of 389 µm with a narrow pore size distribution and a molecular weight cut-off of 490 Da. In different draw solution (DS) concentrations, it was observed that the membranes perform well in all conditions. Considering the PVC-PVP chain entanglements and mobility and the possibility of PVP being washed away, the membranes’ performance at different temperatures indicated that 25–45 °C would be the safe operating range for the fabricated membranes with stable values of 31.0–33.4 LMH and 0.17–0.18 (FO mode) and 33.0–33.4 LMH and 0.23–0.24 (PRO mode) for water flux and specific reverse salt flux.

Synthesis of AgNWs Using High Molecular Weight PVP As a Capping Agent and Their Application in Conductive Thin Films

High molecular weight polyvinylpyrrolidone (PVP) and seeding conditions are considered to have important roles in the synthesis of AgNWs. In this work, we report a versatile synthesis of AgNWs in a salt-free environment and under Ar inert atmosphere using high molecular weight PVP and seeding step during the synthetic process. The high molecular weight PVP was found to efficiently promote the preparation of AgNWs via supporting the proper growth control of AgNWs on {111} facets and selective growth on {100} facets. The seeding step facilitates the formation of seeds such as multiple twinned nanoparticles (MTPs) and single crystal seeds, which promoted the feasible formation of AgNWs. The shape and size of the synthesized AgNWs were characterized by SEM and TEM. The crystalline nature of the synthesized AgNWs was characterized by HRTEM, SAED and XRD, and their LSPR peaks were confirmed by UV-Vis spectroscopy. The conductive properties of the synthesized AgNWs were determined by preparing their thin conductive film on a PET substrate. The prepared AgNWs thin films exhibited good sheet resistance.

High cut-off membrane: evaluation of pore collapse and the synergistic effect of low and high molecular weight polyvinylpyrrolidone

High cut-off (HCO) membranes are the new class of membranes using in several applications like blood purification systems. In the current study, efforts were based upon achieving the HCO membrane with defined properties. Membrane pore collapse is the most challenging problem recognized as an undesirable phenomenon occurring in the drying stage of membrane preparation. Herein, this phenomenon was investigated in detail. The results verified that further of liquid surface tension, other parameters including viscosity, boiling point, polarity, and solubility parameters can be effective on the formation or prevention of this phenomenon. After preventing the pore collapse phenomenon, the simultaneous effect of low and high molecular weights polyvinylpyrrolidone (PVP) to achieve the HCO membrane was evaluated. PVP-K90 is used as a hydrophilizing agent and PVP-K17 is a low molecular weight polymer utilized as a pore-former additive. The synergistic effects of both grades of PVP, provide appropriate membrane features. Contact angle analysis indicated that by incorporation of PVP-K90 in casting solution, membrane hydrophilicity was increased tangibly. With the addition of more content of PVP-K90 higher than 3 wt%, pure water permeability (PWP) of the membrane was decreased. With adding PVP-K17 till 5 wt%, membrane PWP was enhanced significantly which confirmed the pore-former property of this additive. Moreover, mean pore diameter of membranes was increased and subsequently MWCO was enhanced to a higher value with the addition of this pore-former additive. MTT analysis endorsed the biocompatibility of membranes.

Controllable SnO2/ZnO@PPy hollow nanotubes prepared by electrospinning technology used as anode for lithium ion battery

The one-dimensional hollow nanostructure can effectively decrease the diffusion distance of lithium ions and alleviate the volume change of SnO2 during cycling. In this work, SnO2/ZnO hollow nanotubes were obtained from two different molecular weights of Polyvinylpyrrolidone (PVP) by combining electrospinning technology and heat treatment. Mechanism studies indicated the hollow nanotubes with different morphology could be controllable by varying the molecular weight of PVP. SnO2/ZnO nanotubes with high molecular weight PVP as precursor (SnO2/ZnO–H) had smaller diameter and denser structure, which as anode showed better stability and capacity in electrochemical test. The conductivity and stability of SnO2/ZnO–H were further improved after coated with Polypyrrole (PPy) by the in-situ polymerization. The reversible capacity of the batteries was improved, and the volume expansion of the metal oxide was restrained during charging and discharging. The SnO2/ZnO@PPy anode exhibited a high discharge capacity of 626.1 mA h g−1 of 0.2C after 100 cycles, showing an outstanding stability. Therefore, controllable hollow metal oxide nanotubes structures could be obtained via different the molecular weights of precursor polymer. And the hollow nanotubes after coating by PPy as anode materials exhibited the excellent electrochemical performance. This research provided an idea in further design and optimization of anode microstructure for lithium-ion batteries.

The Role of Mixed Reaction Promoters in Polyol Synthesis of High Aspect Ratio Ag Nanowires for Transparent Conducting Electrodes

In recent years, thin silver nanowires (Ag NWs) with diameters smaller than 150 nm have been synthesized by implementation of NaCl or FeCl3 as reaction promoters and high molecular weight polyvinylpyrrolidone (PVP) as the capping agent. However, the yield of Ag NWs still remains low, mostly due to the insufficient aspect ratio (AR) of the synthesized nanostructures and the production of Ag nanoparticles, which is an undesirable by product. This study proposes a modified technique to alleviate the problem by using a mixture of FeCl3/CuCl2 as the reaction promoter and two different types of PVP with molecular weight of 360 k and 40 k as the capping agents. The appropriate mixtures of FeCl3/CuCl2 (molar ratio of 1.48:1.45) and PVP 360 k/40 k (molar ratio of 2:1) allow for the rapid synthesis of NWs with diameter of about 110 nm and length of up to 50 μm. It is revealed that the ARs of the synthesized NWs are much greater. The NWs are then used for the fabrication of transparent conductive films (TCFs). The obtained TCF prepared by a scalable, in-house, and cost-efficient spray apparatus possesses a transmittance of 91%, sheet resistance of 10 Ω/sq, and optical haze value of 6.6%. In fact, the AR of the NWs is increased as much as 1135%, and further the figure␣of merit of the TCFs is improved by as much as 2785%.

Binary polymeric amorphous carvedilol solid dispersions: In vitro and in vivo characterization

Binary polymeric amorphous carvedilol solid dispersions were prepared using solvent method by varying solvent type, polymer type and carvedilol to polymer ratio in order to assess the influence of these factors and maximize carvedilol dissolution rate. Low and high molecular weight polyvinylpyrrolidone, polyvinylpyrrolidone-vinyl acetate copolymer and polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer were used as polymeric carriers in carvedilol to polymer ratios 1:1, 1:2 or 1:4, while absolute ethanol or acetone were used as solvents. Hard gelatin capsules were prepared with carvedilol solid dispersion and lactose monohydrate, mannitol or microcrystalline cellulose. FTIR and PXRD were used to detect carvedilol crystallinity and identify carvedilol-polymer interactions and carvedilol polymorphs. These techniques confirmed carvedilol transition to amorphous state and suggested that hydrogen bonds were formed between carvedilol and polymer molecules. Carvedilol dissolution rate was significantly higher from solid dispersions with higher carvedilol to polymer ratio and solid dispersions prepared using the solvent in which the polymer was more soluble. Solid dispersion with polyvinylpyrrolidone-vinyl acetate copolymer in 1:4 ratio in absolute ethanol displayed the highest carvedilol dissolution rate with 91.78% carvedilol dissolved in the first 30 min. Capsules prepared with the selected solid dispersion and microcrystalline cellulose as diluent displayed the highest carvedilol dissolution rate, with 93.43% carvedilol dissolved within the first 30 min. Carvedilol bioavailability was significantly increased by formulating solid dispersions, while the analysis of serum biochemical parameters excluded damage on liver and kidney function and the lipid profile of animals exposed to investigated drug delivery system.

Proton transport and dielectric properties of high molecular weight polyvinylpyrrolidone (PVPK90) based solid polymer electrolytes for portable electrochemical devices

A simple solution cast route was used to prepare proton conducting solid polymer electrolytes using poly(methyl methacrylate) and poly(vinylpyrrolidone) as polymer hosts and methanesulfonic acid as a proton provider. Fourier transform infrared spectra confirmed functional group interactions between polymers, blended polymers, and acid. Polymer glass transition temperature shifted with increasing acid content in the blend electrolytes provide thermal stability up to 290 °C, verified by differential scanning calorimetry and thermogravimetry analyses. Proton conductivity achieved = 1.16 × 10−4 S/cm at room temperature with an ionic transport number of 0.98. Discharge profiles verified oxidation current < 10 μA for 2 V applied potential for the highly conductive electrolyte, confirming the prepared electrolytes as prime candidates for primary proton cells.

The effect of polyvinylpyrrolidone nanowires on the metabolic activity of Lactobacillus acidophilus

The effectiveness of the use of polyvinylpyrrolidone (PVP) nanowires for increasing the metabolic activity of probiotic cultures of Lactobacillus acidophilus has been shown. PVP nanowires are obtained by electrospinning in two versions: PVPI based on a solution of high molecular weight polyvinylpyrrolidone and distilled water; PVPII based on a solution of two water zinc acetate in distilled water and a solution of high molecular weight PVP in ethanol. In the presence of PVP, there was an increase in viable lactobacillus cells up to 7.4 108 CFU/ml and accumulation of DL-lactic acid during acidification of the test solution to 3.10 and an increase in Eh to + 360.5 mV. PVPI is a more preferred carrier for lactobacilli than PVPII with ZnO. The zinc ions contained in the PVP matrix are capable of causing oxidative stress, followed by the formation of free radicals that damage membrane lipids, proteins and DNA of the prokaryotic cell. The results are aimed at developing new forms of immobilized drugs that can be used as alternative probiotic agents.

Supercritical Assisted Electrospray: An Improved Micronization Process.

A new process is proposed that can largely improve classical electrospray (ESPR) atomization, thanks to the addition of supercritical CO2 (SC-CO2) to the liquid mixture, in which a polymer is dissolved, forming an expanded liquid. The consequent reduction of surface tension and viscosity allows the production of micrometric or nanometric particles of controlled size and distribution at a production rate up to one hundred times that of the traditional process. The new process was applied to particle generation from a very high molecular weight polyvinylpyrrolidone (PVP) and tested at different polymer percentages by weight and at different pressures. Repeatable microparticle diameters and distributions were obtained, ranging between 0.55 and 2.25 µm at PVP concentrations from 1 to 5% w/w and pressures between 80 and 120 bar.

Non Monotonous Effects of Noncovalently Functionalized Graphene Addition on the Structure and Sound Absorption Properties of Polyvinylpyrrolidone (1300 kDa) Electrospun Mats.

Graphene is an attractive component for high-performance stimuli-responsive or ‘smart’ materials, shape memory materials, photomechanical actuators, piezoelectric materials and flexible strain sensors. Nanocomposite fibres were produced by electrospinning high molecular weight Polyvinylpyrrolidone (PVP-1300 kDa) in the presence of noncovalently functionalised graphene obtained through tip sonication of graphite alcoholic suspensions in the presence of PVP (10 kDa). Bending instability of electrospun jet appears to progressively increase at low graphene concentrations with the result of greater fibre stretching that leads to lower fibre diameter and possibly conformational changes of PVP. Further increase of graphene content seams having the opposite effect leading to greater fibre diameter and Raman spectra similar to the pure PVP electrospun mats. All this has been interpreted on the basis of currently accepted model for bending instability of electrospun jets. The graphene addition does not lower the very high sound absorption coefficient, α, close to unity, of the electrospun PVP mats in the frequency range 200–800 Hz. The graphene addition affects, in a non-monotonous manner, the bell shaped curves of α versus frequency curves becoming sharper and moving to higher frequency at the lower graphene addition. The opposite is observed when the graphene content is further increased.

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.

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.

Characterization and quantitation of PVP content in a silicone hydrogel contact lens produced by dual-phase polymerization processing.

Polyvinylpyrrolidone (PVP) has been incorporated over the years into numerous hydrogel contact lenses as both a primary matrix component and an internal wetting agent to increase lens wettability. In this study, complementary analytical techniques were used to characterize the PVP wetting agent component of senofilcon A and samfilcon A contact lenses, both in terms of chemical composition and amount present. Photo-differential scanning calorimetry (photo-DSC), gas chromatography with a flame ionization detector (GC-FID), and high-resolution/accurate mass (HR/AM) liquid chromatography-mass spectrometry (LC-MS) techniques confirmed dual phase reaction and curing of the samfilcon A silicone hydrogel material. Gel permeation chromatography (GPC) demonstrated that high molecular weight (HMW) polymer was present in isopropanol (IPA) extracts of both lenses. High-performance liquid chromatography (HPLC) effectively separated hydrophilic PVP from the hydrophobic silicone polymers present in the extracts. Collectively, atmospheric solids analysis probe mass spectrometry (ASAP MS), Fourier transform infrared (FTIR) spectroscopy, 1 H nuclear magnetic resonance (NMR) spectroscopy, GC-FID, and LC-MS analyses of the lens extracts indicated that the majority of NVP is consumed during the second reaction phase of samfilcon A lens polymerization and exists as HMW PVP, similar to the PVP present in senofilcon A. GC-FID analysis of pyrolyzed samfilcon A and senofilcon A indicates fourfold greater PVP in samfilcon A compared with senofilcon A. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 1064-1072, 2018.