Polyvinylpyrrolidone Layer Research Articles

Polymer enhanced sensitivity and figure of merit SPR optical fiber sensor for high refractive index and wide detection range

A highly sensitive sensor based on surface plasmon resonance (SPR) for high refractive index (RI) sensing is proposed, whose most unique feature lies in a high RI of polyvinylpyrrolidone (PVP) layer embedded between the optical fiber and Au film. The use of the high RI PVP layer amplifies the evanescent wave, thereby increasing sensitivity and improving figure of merit (FOM) of the SPR sensor. In addition, SPR sensor coated with a high RI PVP film breaks through the limitation that the inherent RI of optical fiber can only detect low RI, and can measure higher RI values and expand the measurement range. Experimental results demonstrate that, with a PVP layer thickness of 60 nm, showcasing superior performance compared to sensors lacking a PVP layer. Notably, this SPR sensor offers a cost-effective and straightforward fabrication process, promising broad application in environmental monitoring and biosensing.

Silver Nanowire Networks with Moisture-Enhanced Learning Ability.

The human brain possesses a remarkable ability to memorize information with the assistance of a specific external environment. Therefore, mimicking the human brain's environment-enhanced learning abilities in artificial electronic devices is essential but remains a considerable challenge. Here, a network of Ag nanowires with a moisture-enhanced learning ability, which can mimic long-term potentiation (LTP) synaptic plasticity at an ultralow operating voltage as low as 0.01 V, is presented. To realize a moisture-enhanced learning ability and to adjust the aggregations of Ag ions, we introduced a thin polyvinylpyrrolidone (PVP) coating layer with moisture-sensitive properties to the surfaces of the Ag nanowires of Ag ions. That Ag nanowire network was shown to exhibit, in response to the humidity of its operating environment, different learning speeds during the LTP process. In high-humidity environments, the synaptic plasticity was significantly strengthened with a higher learning speed compared with that in relatively low-humidity environments. Based on experimental and simulation results, we attribute this enhancement to the higher electric mobility of the Ag ions in the water-absorbed PVP layer. Finally, we demonstrated by simulation that the moisture-enhanced synaptic plasticity enabled the device to adjust connection weights and delivery modes based on various input patterns. The recognition rate of a handwritten data set reached 94.5% with fewer epochs in a high-humidity environment. This work shows the feasibility of building our electronic device to achieve artificial adaptive learning abilities.

Hierarchical Fe-Co@TiO2 with Incoherent Heterointerfaces and Gradient Magnetic Domains for Electromagnetic Wave Absorption.

Induced polarization response and integrated magnetic resonance show prosperous advantages in boosting electromagnetic wave absorption but still face huge challenges in revealing the intrinsic mechanism. In this work, we propose a self-confined strategy to construct hierarchical Fe-Co@TiO2 microrods with numerous incoherent heterointerfaces and gradient magnetic domains. The results demonstrate that the use of polyvinylpyrrolidone (PVP) coating is crucial for the subsequent deposition of Co-zeolitic imidazolate frameworks (ZIF-67), the distance of ordered arranged metal ions manipulates the size of magnetic domains, and the pyrolysis of PVP layers restricts the eutectic process of Fe-Co alloys to some extent. As a result, these introduced lattice defects, oxygen vacancies, and incoherent heterointerfaces inevitably generate a strong polarization response, and the regulated gradient magnetic domains realize integrated magnetic resonance, including macroscopic magnetic coupling, long-range magnetic diffraction, and nanoscale magnetic bridge connection, and both of the intrinsic mechanisms in dissipating electromagnetic energy are quantitatively clarified by Lorentz off-axis electron holography. Owing to the cooperative merits, the Fe-Co@TiO2 absorbents exhibit enhanced absorption intensity and strong absorption bandwidth. This study inspires us to develop a generalized strategy for manipulating the size of magnetic domains, and the integrated magnetic resonance theory provides a versatile methodology in clarifying magnetic loss mechanism.

Comprehensive treatment of aroma chemicals industrial effluent with substantial COD content by a novel PVP/polyamide composite hydrophilized RO membrane

A hydrophilized polyvinyl pyrrolidone/polyamide composite high rejection reverse osmosis (HPA-HR RO) membrane was used for the treatment of aroma chemicals containing effluent coming as multiple effect evaporators (MEE) condensate at UK Aromatics Pvt. Ltd., Boisar, Maharashtra. The unique membrane has an active composite layer of polyamide prepared by interfacial polymerization of high diamine (3%) and acid chloride (0.2%) monomer concentrations, which is further coated with polyvinyl pyrrolidone (PVP) to enhance hydrophilicity and chemical inertness. The plant provides removal of total dissolved solids (TDS) from 2500 to 3500 ppm in the feed to a value of 50–100 ppm in the permeate water indicating a rejection of more than 95% of the dissolved solids, with a high water recovery of 80% in permeate. Similarly, complete rejection of color was observed from dark brown to colorless (transparent), whereas the COD content was brought down from 3000 to 5000 mg/L in the MEE condensate to around 1000 mg/L indicating removal of 60 % to 80% depending upon the pressure applied to overcome the high osmotic pressure of the effluent. Physicochemical interactions between the PVP and polyamide skin layers of the composite membrane make the separating barrier durable and highly hydrophilic. Water would have greater sorption due to high affinity with the membrane and higher diffusion coefficient from its smaller size, while the less polar esters that constitute most of the COD would have low interaction and their larger molecular sizes make them less diffusive. The recovered permeate water has been reused in various internal industrial applications like cooling towers, cleaning, etc. at UK Aromatics.

Enhancing performance of tin-based perovskite solar cells by polyvinyl pyrrolidone doping strategy

The power conversion efficiency (PCE) of tin-based perovskite solar cells (TPSCs) was significantly improved when polyvinyl pyrrolidone (PVP) was doped into the formamidinium tin iodide (FASnI3) layer with an optimized doping mass. After doping, the FASnI3 grain size, film smoothness and average carrier lifetime were largely enhanced, which demonstrate the crystallization quality improvement to FASnI3. The champion PCE of the enhanced TPSC was improved to 7.83%, which is relatively 27% larger than that of the control, 6.15%. After continuous storage for 15 days, the PCE of the enhanced TPSC remained 74.4% of its original value. Using the finite difference time domain (FDTD) simulation method, we demonstrated that the light absorption ratio of the FASnI3:PVP layer was larger than that of the FASnI3 , and the photo-generated carrier density of the enhanced TPSC was approximately 2% ∼ 3% larger than that of the control. The ultimate efficiency of the enhanced TPSC was calculated to be 26.23%. It is potential to dope PVP into FASnI3 to further enhance the device performance of TPSCs.

Chlorogenic acid-loaded sandwich-structured nanofibrous film developed by solution blow spinning: Characterization, release behavior and antimicrobial activity

In this work, solution blow spinning (SBS) was used to rapidly develop a sandwich-structured nanofibrous film with an outer layer of polyurethane (PU) nanofibers and an inner layer of polyvinylpyrrolidone (PVP) nanofibers with chlorogenic acid (CGA) loading. Scanning electronic microscopy images showed that there were clear boundaries between the inner and outer layers. The hydrogen bonds that formed between the two layers enhanced the thermal stability. Compared to the CGA-loaded film, the sandwich structure increased the elongation at break and tensile strength from 3.01 ± 0.97% to 201.34 ± 9.63% and 0.0120 ± 0.0002 MPa to 0.1569 ± 0.0117 MPa, respectively, and the PU layer endowed the sandwich-structured film with hydrophobic surfaces. Furthermore, the sandwich structure shifted the burst release of the CGA-loaded film to a long-term sustained release within 144 h. In addition, the sandwich-structured film retained the antioxidant and antimicrobial activities of CGA. These results indicated that the sandwich-structured nanofibrous film developed by SBS possesses potential applications in food packaging.

Stabilizing interface of novel 3D-hierarchical porous carbon for high-performance lithium–sulfur batteries

Li–S batteries (LSBs) are promising next-generation rechargeable batteries owing to their high theoretical capacity (1675 mAh g − 1), high energy density (2500 Wh kg−1), and affordability. However, the practical application of LSBs is hindered by rapid capacity fading and poor cycle life due to the shuttle effect of dissolved polysulfides. In this study, 3D-hierarchical porous carbon impregnated with sulfur (S@3DC), followed by coating with polyvinylpyrrolidone (PVP), is used as a cathode for LSB. The 3D-hierarchical carbon possesses high porosity with micro/mesopores and an open framework that enables the electrolyte penetration for fast ion/mass transfer. The Li–S cells employing PVP-coated S@3DC cathode depicts excellent cycling stability with a high initial capacity of ∼1527 mAh g − 1 at 0.1 C, capacity retention of 80.66% after 800 cycles at 1.5 C, and a remarkable rate capability up to a high rate of 2 C. The thin PVP layer coating, used as a buffer layer on the S@3DC surface, contributes appropriate functional groups at the sulfur-carbon interface. These functional groups enhance sulfur immobilization and suppress the shuttle effect; they also provide additional electrochemically active sites on S@3DC surface for accelerating the charge transfer kinetics between electrode and electrolytes.

Coherent Perfect Absorption in a Transparent Polymer Film on a Transparent Substrate Utilizing Total Internal Reflection by Grazing Incidence

A simple scheme for single-channel coherent perfect absorption (CPA) of transparent materials is proposed and experimentally realized using total internal reflection by grazing incidence, with a single dielectric layer sandwiched by semi-infinite dielectric layers. In a 1.48-µm thick polyvinylpyrrolidone (PVP) film, dip-coated on a MgF2 substrate both transparent in the visible, reflectance dips due to nearly 90% absorption by single-channel CPA were observed in the wavelength range of 370–800 nm, with white light from a Xe lamp incident on the side face of the substrate and extracted from the other side through multiple reflections in the PVP layer. This is a simple and inexpensive CPA scheme, and it is expected to have various applications by changing the substrate/polymer material or dispersing molecules in the polymer film. This paper also provides a design guideline for grazing-incidence waveguide-mode sensors using transparent dielectric materials.

Controllable Melting and Flow of Ag in Self-Formed Amorphous Carbonaceous Shell for Nanointerconnection.

Nanointerconnection has been selected as a promising method in the post-Moore era to realize device miniaturization and integration. Even with many advances, the existing nanojoining methods still need further developments to meet the three-dimensional nanostructure construction requirements of the next-generation devices. Here, we proposed an efficient silver (Ag)-filled nanotube fabrication method and realized the controllable melting and ultrafine flow of the encapsulated silver at a subfemtogram (0.83 fg/s) level, which presents broad application prospects in the interconnection of materials in the nanometer or even subnanometer. We coated Ag nanowire with polyvinylpyrrolidone (PVP) to obtain core–shell nanostructures instead of the conventional well-established nanotube filling or direct synthesis technique, thus overcoming obstacles such as low filling rate, discontinuous metalcore, and limited filling length. Electromigration and thermal gradient force were figured out as the dominant forces for the controllable flow of molten silver. The conductive amorphous carbonaceous shell formed by pyrolyzing the insulative PVP layer was also verified by energy dispersive spectroscopy (EDS), which enabled the continued outflow of the internal Ag. Finally, a reconfigurable nanointerconnection experiment was implemented, which opens the way for interconnection error correction in the fabrication of nanoelectronic devices.

Structural, morphological features, and antibacterial behavior of PVA/PVP polymeric blends doped with silver nanoparticles via pulsed laser ablation

Abstract Polyvinyl alcohol (PVA)/polyvinylpyrrolidone (PVP) blends doped with silver nanoparticles (AgNPs) have been fabricated using laser ablation technique in one spot. The physical features of AgNPs@PVA/PVP layers were detected by XRD, FTIR, and FESEM techniques. Regarding XRD analysis upon different laser ablation times, and silver content induces a variation of PVA/PVP peaks intensities. The surface morphology was exhibited as well size and particle distribution of AgNPs through the blend surfaces. Further, the particle size of AgNPs increases with ablation time from 45.3 nm to 55.4–81.3 nm for the t = 5.0 and 20.0 min, respectively. Besides, the roughness average increased from 60.99 nm at t = 0 min to 102.4 nm at t = 20 min. Besides, the highest contact angle of 61.3 ± 3.1° was detected for pristine PVP/PVP, which decreased with increasing silver content, reaching 38.1 ± 2.1° at t = 20 min. Moreover, the highest cell viability percentage is recorded by the highest silver content composite by 97.1 ± 3.2%. Further, the antibacterial activity was examined and showed that the inhibition zone reached around 17.3 ± 1.9 and 17.1 ± 2.1 mm against Escherichia coli and Staphylococcus aureus, receptively. The fabricated AgNPs@PVA/PVP films could be suggested to be utilized for wound healing/dressing application.

Radiation Modified CS/PVA Film with PVP Coating as Cu Adsorbent Material

Chitosan/Polyvinyl alcohol (CS/PVA) films were coated with layer of polyvinyl pyrrolidone (PVP) to improve its mechanical strength. In this study, chitosan/PVA mixture was first cast into film. The films were later dipped into different concentrations of PVP solutions at 1%, 3%, and 5%. They were then exposed to gamma (γ) radiation at 5,10,20 and 30 kGy. The tensile strength of chitosan/PVA films coated with 1% PVP was found to increase up to 31%. Elongation at break was improved by 1% PVP coating. The CS/PVA Removal Efficiency (RE) with or without PVP coatings were not affected by γ irradiation. Result shows that the best settings to enhance the tensile strength of CS/PVA films for Cu adsorption application was 1% PVP coating at 5 kGy γ radiation.

Polyvinylpyrrolidone Assisted Preparation of Highly Conductive, Antioxidation, and Durable Nanofiber Composite with an Extremely High Electromagnetic Interference Shielding Effectiveness.

With booming development of electronics, electromagnetic interference (EMI) shielding materials based on conductive polymer composites (CPCs) have received increasing attention. However, it remains challenging to develop flexible and lightweight CPCs with excellent stretchability, breathability, durability, and high EMI shielding effectiveness (EMI SE). Here, we propose a facile polyvinylpyrrolidone (PVP) assisted preparation of highly electrically conductive and durable nanofiber composites for high performance EMI shielding. The PVP layer could not only greatly enhance the interfacial interaction between the Ag nanoparticles (AgNPs) and hence the mechanical properties (both tensile strength, Young's modulus and elongation at break) of the polymer nanofiber membrane but also forms a protection layer preventing the AgNPs from oxidizing. The electrical conductivity of the nanofiber composite can reach up to 245.7 ± 30.6 S/cm, which is, to a large degree, maintained after cyclic stretching, abrasion, and ultrasonic washing. In addition, the nanofiber composite exhibits excellent breathability, antibacterial, and Joule heating performance. When used as the EMI shielding material, the nanofiber composite shows an extremely high SE and SSE of ∼96.9 dB and 169.7 dB cm3/g, respectively, and EMI shielding performance possesses outstanding stability and durability. This multifunctional nanofibrous composite membrane exhibits promising applications in wearable electronics.

The effects of polyvinylpyrrolidone molecular weight on defect-free filling of through-glass vias (TGVs)

Through-glass vias (TGVs) have been extensively researched due to the unique properties of glass, including low dielectric constant, high transparency, high mechanical, thermal and chemical resistance, and low cost. The TGVs are typically filled with Cu by electrodeposition to make electrical connections in high-performance electronics with 3D integration. The Cu electrodeposition process employed to fill the through-holes is similar to the one used for printed circuit boards (PCBs), and defect-free Cu can be achieved with a butterfly filling mechanism. This study introduces the defect-free Cu filling of TGVs using polyvinylpyrrolidone (PVP) as a leveler. The effects of PVP molecular weight on the formation of suppression layers on the Cu surface was examined by electrochemical analyses. It was found that the smaller PVP (10,000g/mol) was beneficial, forming a more compact suppression layer. In contrast, the layer of larger PVPs (360,000g/mol) contained a large number of defects where the accelerator could adsorb, resulting in conformal electrodeposition. As a result, the PVP with a molecular weight of 10,000g/mol led to defect-free butterfly filling at TGVs with increasing the filling performance by 20% compared to the larger PVP.

Understanding the Work Function Modification by a Self‐assembled Polyvinylpyrrolidone Layer in Inverted Organic Solar Cells

Polyvinylpyrrolidone (PVP) has been successfully used as the cathode interfacial layer (CIL) in organic solar cells (OSCs) for work function (WF) modification. However, detailed insight into the effect of a PVP interlayer on the physicochemical properties of the indium tin oxide (ITO) electrode in inverted OSCs (I‐OSCs) is still largely absent. Herein, the ITO/PVP interface is investigated by photoelectron spectroscopy and the mechanisms for the energy level alignment of PVP on different substrates in general are unraveled. The results indicate that the dipole formation that reduces the WF is driven by not only the directional intrinsic molecular dipole moments associated with the γ‐lactam of PVP, but also an additional dipole step with the same direction created by the image charges in the contacting (semi‐)conductor layer. In addition, high‐performance inverted OSCs (I‐OSCs) are achieved by introducing a self‐assembled ultrathin PVP layer using a simple immersion method. This work provides enhanced understanding of the PVP‐based CIL and demonstrates its great potential in I‐OSC fabrication, which can pave the way to simplified manufacturing of low‐cost and large‐area devices in organic electronic technologies.

Electrospun Polyvinylpyrrolidone-Gelatin and Cellulose Acetate Bi-Layer Scaffold Loaded with Gentamicin as Possible Wound Dressing.

Acceleration of wound healing can be achieved with the use of wound dressings. Through the electrospinning technique, a polymeric scaffold composed of two layers was processed: a gelatin and polyvinylpyrrolidone layer with gentamicin, and a second layer of cellulose acetate. The conditions for the electrospinning process were standardized for voltage parameters, feed flow and the distance from the injector to the collector. Once the values of the main variables for the electrospinning were optimized, a three-hour processing time was established to allow the separation of the material from the collector. The obtained material was characterized by observations on scanning electron microscopy, Fourier transform infrared spectroscopy and thermal analysis; contact angle measurement was performed to evaluate wettability properties, and antibacterial activity against Pseudomonas aeruginosa and Staphylococcus aureus were evaluated using the Kirby–Bauer test. The obtained fibers that form the bi-layer scaffold present diameters from 100 to 300 nm. The scaffold presents chemical composition, thermal stability, wettability characteristics and antibacterial activity that fulfill the proposal from this study, based on obtaining a scaffold that could be used as a drug delivery vehicle and a wound dressing material.

The development of a new modified graphite pencil electrode for quantitative detection of Gibberellic acid (GA3) herbal hormone

In this practical work, an electrochemical sensor based on 5-ethyl 5-phenyl barbituric acid (EPBA) on Polyvinylpyrrolidone (PVP) modified pencil graphite (PG) electrode was fabricated for the quantification of Gibberellic acid (GA3). At the beginning, PG electrode was modified by a manual casting layer of PVP. Next, EPBA was placed on PVP/PG using the electrochemical deposition. EPBA/PVP modified PG electrode exhibited stable and strong electro catalytic effect with the archived parameters of ᾳ=0.62, logks = 3.42 and Γ = 8.82 × 10-8 mmolcm−2 for oxidation of GA3. Under the optimization electrochemical parameters, the calibration curve revealed a linear behavior over the concentration range of 15 to 225 nmolL-1 with the limit of detection 4.97 nmolL-1. EPBA acted as an electron-exchange for an enhancing charge transfer at the electrode interface and exploring the selective and sensitive response to GA3. This new developed sensor could practically measure GA3 in wheat and rice samples without serious interference from commonly interfering compounds. Therefore, we recommend EPBA/PVP/PGE sensor as an electrochemical device for determination of GA3 in real samples with convincing analytical results.

Low Temperature (

To achieve fully-solution processed n-i-p perovskite solar cells (PSCs), jet-sprayed silver nanowires (AgNWs) are used to replace vacuum-deposited Ag film as the top electrode of n-i-p structure PSCs. AgNWs are covered with a layer of polyvinylpyrrolidone (PVP) because of the addition of PVP during the growth process of AgNWs. This PVP will deteriorate the conductivity of AgNWs and become a charge extraction barrier as an electrode of a PSC. A low temperature (<40 °C) atmospheric-pressure dielectric-barrier-discharge-jet (DBDjet) is used to post-treat AgNWs after completing the fabrication of n-i-p PSCs. The average cell efficiency improved from 9.069% (without DBDjet treatment) to 12.09% (DBDjet with scan rate of 0.5 cm s−1), and the best performing cell achieves efficiency of 14.037% (DBDjet with scan rate of 1 cm s−1). DBDjet plasma treatment removes PVP, improving the interfacial contacts among AgNWs and between AgNWs layer and hole transport layer; this in turn increases the cell efficiency. Sheet resistance measurement, X-ray photoelectron spectroscopy, water contact angle measurement, and electrochemical impedance spectroscopy all show evidence of the removal of the PVP layer by DBDjet plasma treatment.

Improving the efficiency of perovskite light emitting diode using polyvinylpyrrolidone as an interlayer

A few nanometer-thick polyvinylpyrrolidone (PVP) interlayer between PEDOT:PSS anode and active layer was introduced in a perovskite light-emitting diode (PeLED) in conjunction with nanocrystal pinning (NCP) process. The device with the PVP interlayer exhibited dramatic improvements in performance resulting in current efficiency of 20.89 cd A-1, external quantum efficiency (EQE) of 5.4%, the luminance of 39,023 cd m−2, and FWHM of 18 nm, despite the fact that some degree of intermixing of the layers was expected because identical solvent was used for all three layers (PEDOT:PSS, PVP, and perovskite). The interface between PVP and perovskite layer was investigated by using x-ray and ultraviolet photoelectron spectroscopy (XPS and UPS) sputter depth profiling with Ar gas cluster ion beam. Although obtaining a clear interface in XPS depth profile data was not possible because of partial interlayer mixing and the thinness of the PVP layer, an obvious difference across the interface was extracted in the UPS data. The observed energy level diagram was consistent with the characteristic of hole-only device (HOD) in which charge injection from PEDOT:PSS anode to the perovskite layer was suppressed due to the PVP layer.

Enhanced dielectric properties of PVDF nanocomposites with modified sandwich-like GO@PVP hybrids

ABSTRACTHerein, graphene oxide (GO) nanosheets coated with insulated polyvinyl pyrrolidone (PVP) were integrated into poly(vinylidene fluoride) (PVDF) to investigate the effects of the insulating PVP shell, loading, and its reaction time on the dielectric properties of the nanocomposites. Compared with the pristine GO/PVDF, the GO@PVP/PVDF nanocomposites show an improvement of the filler dispersion, and significantly suppressed conductivity and loss. Activation energies of GO/PVDF and GO@PVP/PVDF nanocomposites are calculated as 1.247 eV and 0.435 eV, respectively, indicating that the presence of PVP layer on the GO surface reduces the relaxation activation energy and makes the relaxation occurrence at low temperatures.

Synthesis and Characterization of Hydrophilic gama-Fe2O3 Nanoparticles for Biomedical Applications

The hydrophilic g-Fe2O3 nanoparticles coated with polyvinylpyrrolidone (PVP) were prepared in one step of the modified polyol method combined with an additional heat treating. The presence of maghemite (g-Fe2O3) phase was confirmed by using X-ray diffraction (XRD) and Raman Spectrometry on powder. FT-IR spectroscopy confirmed the presence of PVP on the nanoparticles surface and the Zeta potential also supported the coating of nanoparticles with a layer of PVP and a good stability in aqueous medium. SEM analysis showed that the prepared g-Fe2O3 nanoparticles have a spherical structural morphology with the tendency of agglomeration. Hysteresis loop shows a ferromagnetic behaviour at room temperature with a saturation magnetization up to 57 emu/g.