Polyvinyl Alcohol/polyvinyl Pyrrolidone Research Articles

Preparation and in- vitro Evaluation of Bioadhesive Vaginal Film of Tinidazole

Bioadhesive vaginal film is becoming a more effective and convenient dosage form compared to suppositories and gel for vaginal application as a method for the treatment of vaginal infections. This study aimed to prepare and characterize bioadhesive films of tinidazole to be used for vaginal delivery over a prolonged period to treat local infections. Fourteen formulas of tinidazole films were prepared by solvent evaporation method. Each film was composed of 10 mg tinidazole with different ratios and concentrations of a polymeric combination of polyvinyl alcohol/ polyvinyl pyrrolidone (PVA/PVP) or polyvinyl alcohol/ hydroxypropyl methylcellulose (PVA/HPMC) for formulas A1-A7 and B1-B7, respectively. The prepared films were evaluated for their physicochemical characteristics, content uniformity, swelling, mucoadhesive strength, mucoadhesive time, and drug release. All the prepared films were transparent, had a uniform thickness (0.1-0.15 mm), and exhibited sufficient flexibility with drug content uniformity. The mucoadhesive strength of films was in the range of 28 ± 0.2 to 75 ± 0.01 g. Films containing PVA/HPMC showed higher swelling and lower mucoadhesive strength than those containing PVA/PVP polymeric combination. The in vitro drug release study showed no significant differences (p > 0.05) among films containing PVA/PVP or PVA/HPMC polymeric combinations. Formulas A3 and B4 were considered as the optimal bioadhesive films containing 3% of PVA: PVP (4:1) and 4% of PVA: HPMC (2:1), respectively as they showed complete flexibility, acceptable mucoadhesive strength and time (43 ± 0.1, 45 ± 0.23 g and 30 ± 0.02, 34 ± 0.01 min, respectively) and prolonged drug release rate. In conclusion, films of formulas A3 and B4 possess the potential as a delivery system for tinidazole for the treatment of vaginal infections at the site of application.

Structural, optical analysis, stress-strain, and dielectric properties of selenium oxide/LaFeO3/blend nanocomposites with tunable properties for optoelectronics and micro-supercapacitors

This work focuses on developing flexible nanocomposites by introducing two types of ceramic nanofillers into a biopolymeric blend for optoelectronic and energy-storing applications. Selenium oxide (SeO2) nanoparticles (NPs) and LaFeO3 NPs were prepared by hydrothermal and solid-state reactions, respectively, and incorporated into the polyvinyl alcohol/polyvinyl pyrrolidone (PVA/PVP) through the solution casting process. Transmission electron microscope and X-ray diffraction tests revealed the creation of hexagonal SeO2 and orthorhombic LaFeO3 NPs, with average sizes of 17 and 93 nm. The blend's degree of crystallinity was dependent on SeO2 NPs and LaFeO3 contents. The infrared absorption spectra revealed the interactions/complexation of the fillers with the blend reactive groups. The scan e-microscope (field emission mode) investigated the films' surface morphology and detected the elements they contain. LaFeO3/SeO2 content impacted stress-strain behavior, raised the tensile strength from 64 to 70.9 MPa, and dramatically lowered the strain at break and toughness. UV–vis-NIR measurements exhibited that the transmittance, extinction coefficient, and refractive index can be tuned by SeO2 and LaFeO3/SeO2 content. The direct (Eg.d)/indirect (Eg.id) band gaps were reduced from 5.25/4.9 eV to 4.95/4.7 eV. The dielectric parameters (constant, loss, energy density, and conductivity) were significantly increased after loading 5.0 wt% LaFeO3/SeO2. The dielectric moduli and Cole-Cole plots were also investigated. The structural modifications and enhancement of the optical features and dielectric parameters make the resulted samples the best candidates for optoelectronic devices and energy-storing applications such as sensors and supercapacitors.

Assessment of fibers from different part of the Calotropis gigantea biomass as a filler of composites foam PVA/PVP

This research explores the extraction and application of cellulose fibers from various parts of plants, specifically young and old stems, as well as seed/fruit skins. The primary focus was on the effective removal of lignin and other extraneous compounds to enhance the properties of cellulose fibers for their subsequent use as fillers in the production of porous composites. These composites were evaluated for their responsiveness to ammonia vapor through a color change test, indicating their potential as intelligent, environmentally friendly packaging materials. The cellulose fibers were isolated through a two-stage process involving delignification using 20 % sodium hydroxide (NaOH) and bleaching with a 5 % hydrogen peroxide (H2O2) and 3.8 % NaOH mixture. These fibers were then characterized using Fourier Transform Infrared Spectroscopy (FT-IR), X-ray Diffractometry (XRD), and Scanning Electron Microscopy (SEM). The analysis revealed that fibers extracted from the younger stem bark exhibited superior characteristics, notably in their crystallinity index (CI), which was 5.16 % higher than that of fibers from other plant parts. Surface morphological studies indicated that the cellulose fibers derived from CG plants possess a hollow shape. When used as fillers, these fibers contributed to the enhanced porosity of polyvinyl alcohol/polyvinylpyrrolidone (PVA/PVP) composites. SEM analysis further demonstrated that the inclusion of fibers with higher degrees of crystallinity significantly increased the composites' porosity. Additionally, composites immobilized with anthocyanins from the Butterfly Pea Flower (BPF) exhibited a notable colorimetric response to environmental pH changes. Thermogravimetric analysis suggested that incorporating these fibers into the composite matrix improves thermal stability. The study's findings underscore the potential of these porous composites as colorimetric indicators, paving the way for their application in smart, eco-friendly packaging solutions.

Synthesis of gel crosslinked composite material from spent cathode carbon blocks and its application in modified asphalt binders

The utilization of spent cathode carbon blocks (SCCB) from aluminum electrolysis has become challenging due to their content of highly toxic cyanides and environmentally harmful fluorides. To achieve reliable recovery and utilization of hazardous waste, targeted research has been conducted on the treatment of waste cathode carbon blocks and their potential application in asphalt pavement. Hydrogen peroxide (H2O2) is employed to remove cyanides from the waste cathode carbon blocks, meeting the construction requirements for transportation areas. Anhydrous calcium chloride is used as a calcium source to precipitate soluble fluorides in the solution. Finally, the waste cathode carbon blocks are gel-crosslinked using polyvinyl alcohol-polyvinyl pyrrolidone, addressing the release of fluorides beyond environmental tolerance. This results in the synthesis of a composite material consisting of calcium fluoride deposits and gel-encapsulated waste cathode carbon blocks (PSB), which exhibits good thermal stability in the temperature range of 0–217 °C. Through DSR and MSCR testing, it has been demonstrated that the gel-crosslinked waste cathode carbon block composite material improves the asphalt's sensitivity to temperature and enhances its resistance to rutting at high temperatures. The 1% PSB/SBS modified asphalt shows the best performance, compared to SBS, the complex modulus (G*) of the modified asphalt increased by 117.4% at 46 °C, and the recovery indices for creep at 64 °C improved by 39.28% (at 0.1 kPa) and 55.65% (at 3.2 kPa), and thermal gravimetric analysis of the asphalt confirms that the addition of PSB improves the asphalt's thermal stability. Fluorescence microscopy analysis reveals that the inclusion of PSB does not affect the morphological development of SBS swelling and plays a stabilizing and supporting role in the asphalt mixture.

Synergy of radical and nonradical degradations triggered by self-floating MnO2/cotton hydrogels with photothermal effect and oxygen vacancy

Persulfate-based advanced oxidation process is a promising technology for the water purification. While the synergy of radical and nonradical degradations are still unfeasible during persulfate activation, which process consumes a large amount of external energy. The self-floating manganese dioxide (MnO2)/cotton hydrogels (MCH) was developed, which achieves solar energy capture and wastewater treatment. In this study, a meticulously designed MCH enables simultaneous interface heating and persulfate activation. The MCH exhibited an excellent photothermal conversion capability with an evaporation rate of 2.89 kg/(m2·h) under 1 sun. The MCH coupled with peroxydisulfate (PDS) achieved a tetracycline (TC) degradation efficiency of 74.53 % under a visible light irradiation in 120 min. Furthermore, the result of TC evaporation experiment showed that 99.43 % of TC can be removed from the evaporated water. Interestingly, it was found that the singlet oxygen (1O2) increased with the concentration of Vo in the MCH during PDS activation process. In contrast to the conventional view, the thermal effect increases the concentration of Vo thus promoting the conversion of superoxide radicals (O2−) to 1O2 in the presence of Mn4+. Additionally, the polyvinyl alcohol/polyvinylpyrrolidone (PVA/PVP) hydrogel with porous structure that provided the oxygen for MnO2, promoting the production of reactive oxygen species. This study provides a new model for simultaneous evaporation and degradation, which deepens the understanding of synergy of radical and nonradical degradations.

Effects of Reduced Graphene Oxide on Structural, Morphological, and Contact Angle Measurements of Poly (Vinyl Alcohol)/Polyvinyl Pyrrolidone Nanofibers

Polymer blend nanofibers are attracting considerable attention due to their wide applications in energy storage, water purification, drug delivery, and wettability studies. To date, research on poly (vinyl alcohol)/polyvinyl pyrrolidone (PVA/PVP) embedded with graphene-related materials like graphene oxide or reduced graphene oxide(rGO) are synthesized from solution mixing and casting into film, with limited efforts on developing polymer blend nanofibrous films. The present study focuses on developing the PVA/PVP blend nanofibrous film embedded with rGO using the electrospinning technique. The X-ray Diffraction (XRD), Field Emission scanning electron microscopy (FESEM), and contact angle measurements are used to investigate the structural, morphological, and wettability of the synthesized nanofibrous film. The rGO is synthesized by the improved Hummer’s method. The study provides insights into the tuning of the contact angles by modifying the morphology of nanofibers. The as-synthesized nanofibers have a diameter of about 150-250 nm and with the increase in rGO weight percentage show a drastic change in contact angle from 64° to 35.2°. These results highlight the modification of the wettability properties of blend nanofiber films by embedding rGO.

Linear/Nonlinear Optical Characteristics of ZnO-Doped PVA/PVP Polymeric Films for Electronic and Optical Limiting Applications

ZnO-doped Polyvinyl alcohol/polyvinyl pyrrolidone (PVA/PVP) polymeric films were prepared in this study through an easy and inexpensive solution-casting method. The scope of the study was based on the structural, dielectric, and optical parameters, as well as on the optical limiting effects of the ZnO-doped polymer blend (PB) as nanocomposite films. The X-ray diffraction (XRD) analysis indicated that the synthesized nanocomposites were semicrystalline. The calculated crystalline size of the polymeric semicrystalline peak decreased as ZnO increased or enhanced the blend polymer. Fourier’s transformer infrared (FT-IR) study confirmed a substantial dispersion of ZnO nanoparticles in a polymeric PVA/PVP matrix. The optical absorption properties suggested focusing on the surface plasmonic peak (SPR). The refractive index values ranged from 1.718 for the pure PB ZnO0 sample in the Hossam, Ibrahim, and Heba model to 3.036 for the PB ZnO5 film from the Anani model. Nonlinear optical parameters (χ((3)), and n(2)) were calculated and analyzed for the PB ZnO nanocomposite films under investigation. The maximum value for χ((1)) was 0.550, while for χ((3)), its susceptibility value was 155.85 × 10−13 esu, and for the nonlinear refractive index (n((2)), it was 20.87 × 10−11 esu. A gradual decrease was revealed in the optical limiting sources, as a high content of ZnO was induced in the blend PVA/PVP polymer. Due to their unique properties, these materials can be used in electronic and optoelectronic devices.

Novel Synergistic Approach: Tazarotene-Calcipotriol-Loaded-PVA/PVP-Nanofibers Incorporated in Hydrogel Film for Management and Treatment of Psoriasis.

Psoriasis is an autoimmune skin disease that generally affects 1%-3% of the total population globally. Effective treatment of psoriasis is limited because of numerous factors, such as ineffective drug delivery and efficacy following conventional pharmaceutical treatments. Nanofibers are widely being used as nanocarriers for effective treatment because of their multifunctional and distinctive properties, including a greater surface area, higher volume ratio, increased elasticity and improved stiffness and resistance to traction, favorable biodegradability, high permeability, and sufficient oxygen supply, which help maintain the moisture content of the skin and improve the bioavailability of the drugs. Similar to the extracellular matrix, nanofibers have a regeneration capacity, promoting cell growth, adhesion, and proliferation, and also have a more controlled release pattern compared with that of other conventional therapies at the psoriatic site. To ensure improved drug targeting and better antipsoriatic efficacy, this study formulated and evaluated a tazarotene (TZT)-calcipotriol (CPT)-loaded nanofiber and carbopol-based hydrogel film. The nanofiber was prepared using electrospinning with a polyvinyl alcohol/polyvinylpyrrolidone (PVA/PVP) K-90 polymeric blend that was later incorporated into a carbopol base to form hydrogel films. The prepared nanofibers were biochemically evaluated and in vitro and in vivo characterized. The mean diameters of the optimized formulation, i.e., TZT-loaded polyvinyl alcohol/polyvinylpyrrolidone nanofiber (TZT-PVA/PVP-NF) and TZT-CPT-loaded polyvinyl alcohol/polyvinylpyrrolidone nanofiber (TZT-CPT-PVA/PVP-NF) were 244.67 ± 58.11 and 252.31 ± 35.50 nm, respectively, as determined by scanning electron microscopy, and their tensile strength ranged from 14.02 ± 0.54 to 22.50 ± 0.03 MPa. X-ray diffraction revealed an increase in the amorphous nature of the nanofibers. The biodegradability studies of prepared nanofiber formulations, irrespective of their composition, showed that these completely biodegraded within 2 weeks of their application. The TZT-CPT-PVA/PVP-NF nanofibers exhibited 95.68% ± 0.03% drug release at the end of 72 h, indicating a controlled release pattern and following Higuchi release kinetics as a best-fit model. MTT assay, antioxidant and lipid profile tests, splenomegaly assessment, and weight fluctuation were all performed in the in vitro as well as in vivo studies. We found that the TZT-CPT-PVA/PVP-NF-based hydrogel film has high potential for antipsoriatic activity in imiquimod-induced Wistar rats in comparison with that of TT-PVA/PVP-NF nanofibers.

Essential Oils as Antimicrobial Active Substances in Wound Dressings.

Wound dressings for skin lesions, such as bedsores or pressure ulcers, are widely used for many patients, both during hospitalization and in subsequent treatment at home. To improve the treatment and shorten the healing time and, therefore, the cost, numerous types of wound dressings have been developed by manufacturers. Considering certain inconveniences related to the intolerance of some patients to antibiotics and the antimicrobial, antioxidant, and curative properties of certain essential oils, we conducted research by incorporating these oils, based on polyvinyl alcohol/ polyvinyl pyrrolidone (PVA/PVP) biopolymers, into dressings. The objective of this study was to study the potential of a polymeric matrix for wound healing, with polyvinyl alcohol as the main material and polyvinyl pyrrolidone and hydroxypropyl methylcellulose (HPMC) as secondary materials, together with additives (plasticizers poly(ethylene glycol) (PEG) and glycerol), stabilizers (Zn stearate), antioxidants (vitamin A and vitamin E), and four types of essential oils (fennel, peppermint, pine, and thyme essential oils). For all the studied samples, the combining compatibility, antimicrobial, and cytotoxicity properties were investigated. The obtained results demonstrated a uniform morphology for almost all the samples and adequate barrier properties for contact with suppurating wounds. The results show that the obtained samples containing essential oils have a good inhibitory effect on, or antimicrobial properties against, Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853, and Candida albicans ATCC 10231. The MTT assay showed that the tested samples were not toxic and did not lead to cell death. The results showed that the essential oils used provide an effective solution as active substances in wound dressings.

The effect of Ag2O/NbO2 nanostructures on the dielectric characteristics of PVA/PVP bled used in electronics

Nanocomposites may be employed in a wide range of applications, including as biosensors, diodes, antibacterial, transistors, and so on. In the current study, a new type of nanocomposites (PVA-PVP-Ag2O-NbO2) were prepared by solution casting method. The polymeric mixture (polyvinyl alcohol-polyvinylpyrrolidone) was produced with various polyvinyl alcohol concentration (50 wt. %), polyvinylpyrrolidone (50% wt.%), as well as niobium oxides and silver nanoparticles oxides were added to the polymeric mixture with different percentages, which are (0.0025, 0.005, 0.0075 and 0.01 wt. percent). The effect of each of the niobium oxide nanoparticles and silver oxide nanoparticles on A.C was studied. The alternating electrical properties were studied at room temperature in the frequency range (100Hz-5MHz). Results of the experiment showed an increase of both the dielectric constant and the alternating conductivity of electricity and the loss of dielectric of polymeric mixture (PVA-PVP) an increase in increasing concentrations of niobium oxide nanoparticles and silver oxide nanoparticles, and the dielectric loss and dielectric constant of nanocomposites (PVA-PVP-Ag2O-NbO2) a rise in increasing in the applied electric field’s frequency, and alternating With increasing frequency, electrical conductivity increases.

Study the effect of mercuric ions concentration on some optical properties of Polyvinyl (alcohol/pyrrolidone) blend film

In the present work, the casting process was used to prepare polymeric films based on Polyvinyl alcohol/Polyvinylpyrrolidone (PVA/PVP) loaded with various weight percentages of HgCl2. The morphology and the microstructure of the synthesized samples were studied using Scanning Electron Microscope (SEM), Atomic force microscope (AFM), x-Ray Diffraction (XRD), and Fourier-transform infrared spectroscopy (FT-IR) techniques. UV/VIS/NIR spectrophotometer was implemented to scientifically check the optical elucidation. All films between the two phases are characterized by substantial integration of HgCl2 and PVA/PVP. The scanning electron microscope shows a morphology modification of the blend surface with the mercuric chloride substantive. The roughness calculated from AFM images increased with increasing HgCl2. The agglomeration of the particles made a significant influence on the optical transmittance properties of pure PVA/PVP. Due to the growth of distortion and imperfection in the structure of the blend matrix by the addition of HgCl2, there is a modification in the engineering bandgap, localized state’s order, coefficient of absorption, and optical conductivity. The dispersion and oscillator energies were calculated using the Wemple and Di Domenico (DDW) model for a single oscillator. Various theoretical relations between energy gaps and refractive indices were used to calculate the average refractive index of each sample. Further, the nonlinear refractive index and optical susceptibilities of polymer composite samples were enhanced by increasing the percentage of HgCl2. The influence of loading on the optical limiting of the blend was investigated via He-Ne and green diode lasers. The results indicate the ability to use our flexible films in various optoelectronic devices.

Recyclable visible-light photocatalytic composite materials based on tubular Au/TiO2/SiO2 ternary nanocomposites for removal of organic pollutants from water

The highly active free radicals generated by semiconductor materials in the photocatalytic technology can achieve efficient degradation of organic pollutants. Tubular Au/TiO2/SiO2 ternary nanocomposite is fabricated under high-temperature ablation via the sacrificial template and noble metal deposition. SiO2 is deposited to inhibit the growth of grain size of TiO2. The tubular structure can effectively increase the scattering times and improve the utilization of visible-light. Au nanoparticles (Au NPs) absorb visible-light and promote the formation of photogeneration-hole pairs. Besides, Au NPs can also be used as an electron acceptor to delay the recombination rate of photogeneration electron-hole pairs, and improve the photocatalytic activity. Furthermore, the polyvinyl alcohol/polyvinylpyrrolidone (PVA/PVP) gel was used to load and immobilize TiO2-based catalytic materials, and the composite gel still has a good photocatalytic activity with favorable cyclability. This work opens up a new opportunity for designing the photocatalytic composite material with long-term catalytic stability and excellent reusability.

Tailoring the linear and nonlinear optical characteristics of PVA/PVP polymeric blend using Co0.9Cu0.1S nanoparticles for optical and photonic applications

In this work, the linear and nonlinear optical characteristics of polyvinyl alcohol/polyvinyl pyrrolidone (PVA/PVP) polymeric blend have been tailored via Co0.9Cu0.1S nanoparticles (CCS NPs) incorporation. Plain PVA/PVP polymeric blend and different (0.1, 0.5, 1.0, 5.0 and 10.0) wt% of Co0.9Cu0.1S NPs polymeric nanocomposites (PNCs) were prepared by solution casting technique. The samples' surface morphology, structures’ variation, linear and nonlinear optical characteristics were explored using scanning electron microscopy, Fourier transform infrared (FT-IR) and UV–Vis–NIR spectrophotometry respectively. The FT-IR spectra analysis exposes the successful interaction and complexation of the CCS NPs with the host blend structure. The UV–Vis–NIR spectra analysis shows that the direct and indirect optical energy bandgap (Eg) of the host blend decreases from 5.15 eV to 4.94 eV–3.86 eV and 3.05 eV (10.0 wt% of CCS PNC) respectively. The Urbach energy of the plain blend increases from 0.41 eV to 1.18 eV (10.0 wt% of CCS PNC), which reveals the increase of the defects density due to CCS NPs incorporation. Also, the refractive index (n), dielectric constants (real εr and imaginary εi), optical conductivity, linear optical susceptibility (χ(1)), third-order nonlinear optical susceptibility (χ(3)) and nonlinear refractive index (n2) of the PVA/PVP blend are greatly enhanced due to CCS incorporation. The enhancement in the linear and nonlinear optical performance of the plain PVA/PVP blend via Co0.9Cu0.1S NPs incorporation nominates their applications in various optical and photonic devices.

Surface Reconstruction on Electro-Spun PVA/PVP Nanofibers by Water Evaporation.

Tailoring the secondary surface morphology of electro-spun nanofibers has been highly desired, as such delicate structures equip nanofibers with distinct functions. Here, we report a simple strategy to directly reconstruct the surface of polyvinyl alcohol/polyvinylpyrrolidone (PVA/PVP) nanofibers by water evaporation. The roughness and diameter of the nanofibers depend on the temperature during vacuum drying. Surface changes of the nanofibers from smooth to rough were observed at 55 °C, with a significant drop in nanofiber diameter. We attribute the formation of the secondary surface morphology to the intermolecular forces in the water vapor, including capillary and the compression forces, on the basis of the results from the Fourier-transform infrared (FTIR) and X-ray photoelectron (XPS) spectroscopy. The strategy is universally effective for various electro-spun polymer nanofibers, thus opening up avenues toward more detailed and sophisticated structure design and implementation for nanofibers.

Enhancement of dispersion stability of inorganic additives via poly(sodium-4-styrenesulfonate) treatment geared to hydrogel applications.

This study reports the preparation of poly(sodium-4-styrene sulfonate) (PSS) treated bentonite and clinoptilolite to prevent the agglomeration and sedimentation of these inorganic fillers during the preparation of hydrogel. For this purpose PSS treated fillers were prepared by using various techniques (dip and dry, hydrothermal, one-step ball milling and ultrasonication methods). The most suitable technique for preparing these PSS treated inorganic fillers (abbreviated as BP-dip and CP-dip) was the dip and dry method. BP-dip and CP-dip based polyvinyl alcohol/polyvinylpyrrolidone (PVA/PVP) composite hydrogels were prepared using the freeze/thawing method after the addition of one of BP-dip and CP-dip inorganic fillers in various amounts. The swelling properties, stability behaviors and Rhodamine B (RhB) adsorption of the composite hydrogels were studied. It was found that the swelling degrees of CP-dip and BP-dip based composite hydrogels with 25 mg of filler were higher than that of all other samples. The kinetic mechanism of RhB adsorption process and the related characteristic kinetic parameters were investigated by Pseudo kinetic models. The adsorption kinetics results for RhB adsorption were found best fitted with pseudo-second-order kinetics model. The maximum RhB adsorption capacity was determined to be for PVA/PVP-CP-dip25, which was 3.3 times higher than that of the unfilled PVA/PVP hydrogel.

Rational Design of a High Performance and Robust Solar Evaporator via 3D-Printing Technology.

Utilizing the broad-band solar spectrum for sea water desalination is a promising method that can provide fresh water without sophisticated infrastructures. However, the solar-to-vapour efficiency has been limited due to the lack of a proper design for the evaporator to deal with either a large amount of heat loss or salt accumulation. Here, these issues are addressed via two cost-effective approaches: I) a rational design of a concave shaped supporter by 3D-printing that can promote the light harvesting capacity via multiple reflections on the surface; II) the use of a double layered photoabsorber composed of a hydrophilic bottom layer of a polydopamine (PDA) coated glass fiber (GF/C) and a hydrophobic upper layer of a carbonized poly(vinyl alcohol)/polyvinylpyrrolidone (PVA/PVP) hydrogel on the supporter, which provides competitive benefit for preventing deposition of salt while quickly pumping the water. The 3D-printed solar evaporator can efficiently utilize solar energy (99%) with an evaporation rate of 1.60 kg m-2 h-1 and efficiency of 89% under 1 sun irradiation. The underlying reason for the high efficiency obtained is supported by the heat transfer mechanism. The 3D-printed solar evaporator could provide cheap drinking water in remote areas, while maintaining stable performance for a long term.

Investigation of the effect of in-situ grown PPy on low frequency dielectric properties and other properties of PVA-PVP blend film

Present study is carried out to understand the effect of conducting polymer, polypyrrole (PPy) on structural, morphological, thermal and dielectric properties of bio-compatible polymer blend film of polyvinyl alcohol (PVA) and polyvinyl pyrrolidone (PVP). The growth of PPy in the matrix of PVA–PVP was analyzed using XRD, FT-IR and SEM studies. The shifting in positions and broadening of XRD diffraction peaks of PVA–PVP-PPy from that of PVA–PVP indicates the structural modification and reduction in the crystallinity of the PVA–PVP due to incorporation of PPy. The SEM studies suggest scattered growth of PPy in PVA–PVP matrix at lower concentration of pyrrole monomer. As the monomer concentration is increased, the uniform and interconnected growth of PPy was observed in SEM micrographs. The TGA thermograms show faster thermal degradation of PVA–PVP- PPy films at lower temperature as compared to PVA–PVP films. The blend films of PVA–PVP- PPy exhibited enhanced values of dielectric constant and ac conductivity as compared to the virgin blend film which are observed to increase with increasing concentration of PPy. The high dielectric constant with high ac conductivity exhibited by PVA–PVP-PPy film suggests its possible application as flexible dielectric material for the development of biosensors, energy storage devices in field of green organic electronics.

Microstructural features, spectroscopic study and thermal analysis of potassium permanganate filled PVA–PVP blend films

Potassium permanganate (KMnO4) filled polyvinyl alcohol (PVA)–polyvinylpyrrolidone (PVP) polymeric blend films have been prepared by solution casting technique, with filler levels (FL) varying from 0.01 up to 4.70 mass%. The microstructural features, thermal properties and spectroscopic properties of these films have been studied using powder XRD, AFM, Fe-SEM, DSC, TG and FTIR. FTIR spectra for filled samples indicated a major molecular structural modification, involving conversion of the hydroxyl (OH) group into ketones at higher FLs. The bands showed a clear distortion in the wide OH band especially at higher FLs of 3.80 mass% and 4.70 mass%. This is confirmed from the TG scans, whose thermal degradation signature reveals multiple stages of degradation for FL of 2.8 mass%, 3.8 mass% and 4.7 mass%. The DSC, TG and DTA curves revealed that value of T g was found to decrease on addition of filler in the PVA–PVP blend, whereas the thermal stability of the filled samples was found to increase. The XRD results revealed that the incorporation of KMnO4 in PVA–PVP blend made the sample more amorphous. At low FLs, AFM and SEM micrographs show evidence for formation of nano-particles in the host polymeric material only at the lowest FL of 0.01 mass% with uniform dispersion of nano-structures, whereas at moderate FLs, there are micro-structures in the polymeric host, followed by agglomeration of filler induced chemical species as the FL increases beyond 2.8 mass%. Therefore, KMnO4 filled PVA–PVP blend films show desirable properties expected from a good solid polymeric electrolyte, for FLs below 1.5 mass%.

Preparation, characterization, and drug release study of ibuprofen-loaded poly (vinyl alcohol)/poly (vinyl pyrrolidone) bilayer antibacterial membrane

Controlling wound pain, absorption of wound exudate, and minimizing the frequency of changing the dressing are necessary parameters to facilitate wound-healing process. Hence, stable hydrophilic hydrogels applied in the form of film with the capability of wound exudate absorption and anti-inflammatory drug release may be used as an ideal wound dressing. Furthermore, physically crosslinked hydrogels are preferred over chemical ones because of being free from remaining harmful chemicals and adverse effects on the entrapped drugs. Thus, in this study, we developed an antibacterial bilayer membrane composed of a combination of polyvinyl alcohol/polyvinyl pyrrolidone (PVA/PVP) with the ability to release Ibuprofen (IBP). First, 1% IBP was incorporated in different ratios of PVA/PVP solution (90:10, 80:20, and 70:30); then, the hydrogels were crosslinked through repetitive freeze-thawing cycles followed by lyophilization, as the bottom layer. Second, the top layer was made in the same way but without the drug. Morphology, mechanical properties, swelling ratio, degradation rate, water vapor transmission rate (WVTR), and in vitro drug release of bilayer membranes were evaluated, then the content of PVP was optimized. The results indicated that the sample with the PVA/PVP ratio of 80:20 encompassed large and interconnected pores and also a proper swelling degree (500% in 48 h), weight loss (60% during 12 days) and WVTR (2721.1 ± 93.3 g/m2); thus, it is considered as the optimized membrane. MTT and antibacterial assays also showed acceptable viability and bactericidal activity for the membranes containing IBP. In conclusion, the prepared bilayer membrane can absorb wound exudate within the dressing matrix, release IBP locally, and keep its stability at the wound site. The bilayer membrane also exhibited an excellent antibacterial feature for accelerating the wound-healing process.

Structure–property relation in copper nanoparticles-based PVA/PVP composites

Copper nanoparticles composition-based polyvinyl alcohol/polyvinylpyrrolidone (PVA/PVP) composite films were prepared for select concentrations. AC conductivity, dielectric permittivity, UV–visible and FTIR studies along with X-ray diffraction analysis were carried out on these composites. From this conductivity study, DC conductivity was estimated along with hopping potential, hopping length and thermal conductivity using power law of the frequency-dependent AC conductivity. A correlation study of these parameters using functional analysis method to establish structure–property relation in these composites was also carried out.