Concentrated Polymer Solutions Research Articles

Enhancing pollutant removal from contaminated soils using yield stress fluids as selective blocking agents

This work presents a novel technique consisting in the use of yield stress fluids as blocking agents in porous media presenting pore-scale heterogeneities. The key feature of this method is that yield stress fluids only flow through the pores having a minimum size that depends on the applied pressure gradient. These fluids remain immobile in more and more pores as the pressure gradient is decreased. Therefore, the dimension of the pores which are invaded by the yield stress fluid can be controlled by adjusting the applied pressure gradient. Moreover, yield stress fluids are highly suitable blocking agents given the extremely high viscosity values that they exhibit in the pores. This allows for the diversion of the flow from greater to smaller pores during subsequent waterflooding stages, thus enhancing pollutant removal from the flow paths of small hydraulic conductance. A series of multiphase flow experiments were conducted in this study using well-characterized cores of artificial A10 sintered silicate. In these experiments, semidilute aqueous solutions of xanthan gum biopolymer were used as yield stress fluids to block the greatest pores. By doing so, considerably more pollutant was recovered by waterflooding. Furthermore, it was shown that an increase in polymer concentration does not always lead to a decrease in the size of the pores invaded by the blocking agent. Indeed, concentrated polymer solutions generate higher pressure gradients throughout the porous medium, which facilitates the invasion of small pores. Nevertheless, depending on the value of the yield stress-pressure gradient ratio, they may also develop extremely high viscosities that slow down their flow through such small pores. This work also presents a method to measure the volume of blocked pores using the results of tracer tests. The reported results suggest that using a polymer solution developing a yield stress as a selective blocking agent is a promising technique for soil remediation.

Controlling the molecular orientation of a novel diketopyrrolopyrrole-based organic conjugated polymer for enhancing the performance of organic field-effect transistors

A novel organic conjugated copolymer p(DPP-BZC) was utilized as a solution-processable organic semiconductor and its large area of the unidirectionally oriented thin film was fabricated by the Ribbon-shaped floating film transfer (FTM) method. Organic field-effect transistors (OFETs fabricated using oriented thin films of this polymer demonstrated a clear p-type semiconducting behaviour and anisotropic charge carrier transport. A maximum orientation with a dichroic ratio of 5.1 was obtained in the FTM-processed thin film under optimized conduction with liquid substrate viscosity, temperature and polymer solution concentration of 6.12 cst, 50 °C and 3% (w/v), respectively. Out-of-plane XRD and in-plane GIXD results revealed that oriented thin films of this copolymer are semicrystalline and adopt purely edge-on on conformation. The implication of surface modification of Si/SiO 2 gate dielectric utilizing HMDS. OTS and CYTOP on the charge carrier transport revealed that substrate with high-surface-energy hampers the on/off ratio, operating voltage and charge carrier mobility (μ). On the other hand, Si/SiO 2 substrate treated with CYTOP having relatively lower surface energy demonstrated the best device performance with the highest μ of 2.7 x 10 −2 cm 2 /Vs, which is > 30 times higher as compared to that of its non-oriented spin-coated device counterparts an μ of 8.0 x 10 −4 cm 2 /Vs. • Synthesis of novel conjugated polymer p(DPP-BZC) and utilization of its oriented thin films for OFET fabrication. • Utilizing the FTM technique an oriented thin film with DR of 5.1 was achieved under optimized conditions. • Purely edge-on orientation in the oriented film was confirmed by XRD and GIXD. • Surface passivation was found to be desired and amongst various surface modifiers used, CYTOP exhibited the best performance. • OFETs utilizing oriented thin films exhibited the mobility of 2.7 x 10 −2 cm 2 /Vs, which was >30 times higher than corresponding spin-coated devices.

Effects of pH and incubation temperature on properties of konjac glucomannan and zein composites with or without freeze-thaw treatment

This work investigated the effect of pH and incubation temperature on the morphology and properties of konjac glucomannan (KGM)-zein composites with or without freeze-thaw treatment. When the incubation temperature was 90 °C, the composites prepared in the pH range of 10.5–11.5 were concentrated polymer solutions, while the composites prepared in the pH range of 12.0–13.0 were gels. The pH of 12.5 was found to form the composites with the most dense microstructure, the highest storage modulus and crystallinity, and the greatest ability to resist plastic deformation during compression. The composites tended to form gels with the increase of incubation temperature from 40 °C to 90 °C at pH = 12.5. The temperature of 90 °C was found to form the composites with the most dense microstructure, the greatest ability to resist plastic deformation during compression, and the highest crystallinity and frequency stability. The composite prepared at an incubation temperature of 70 °C and a pH = 12.5 had similar microstructure, rheological properties, and texture properties to that prepared at an incubation temperature of 80 °C and a pH = 12.0. The freeze-thaw treatment caused a slight increase in storage modulus (G′) and crystallinity when the composites were concentrated polymer solutions. When the composites were gels, the freeze-thaw treatment caused a rough and inhomogeneous microstructure, increased the G′ and the ability to resist plastic deformation during compression, decreased the springiness, and altered the internal water mobility. pH and incubation temperature play important roles in the morphology and properties of KGM-zein composites. • The composites were concentrated polymer solutions prepared at 80 °C and pH ≤ 11.5. • The composites were gels prepared at 40 °C–80 °C and pH = 12.5. • 70 °C and pH = 12.5 endowed the composite with similar properties to 80 °C and pH = 12.0. • Freeze-thaw treatment had different effects on gel and concentrated polymer solution.

Theory of self-coacervation in semi-dilute and concentrated zwitterionic polymer solutions.

Based on the random phase approximation, we develop a molecular theory of self-coacervation in zwitterionic polymer solutions. We show that the interplay between the volume interactions of the monomeric units and electrostatic correlations of charged groups on a polymer backbone can result in liquid-liquid phase separation (self-coacervation). We analyse the behavior of the coacervate phase polymer concentration depending on the electrostatic interaction strength - the ratio of the Bjerrum length to the bond length of the chain. We establish that in a wide range of polymer concentration values - from a semi-dilute to a rather concentrated solution - the chain connectivity and excluded volume interaction of the monomeric units have an extremely weak effect on the contribution of the electrostatic interactions of the dipolar monomeric units to the total free energy. We show that for rather weak electrostatic interactions, the electrostatic correlations manifest themselves as Keesom interactions of point-like freely rotating dipoles (Keesom regime), while in the region of strong electrostatic interactions the electrostatic free energy is described by the Debye-Hückel limiting law (Debye regime). We show that for real zwitterionic coacervates the Keesom regime is realized only for sufficiently small polymer concentrations of the coacervate phase, while the Debye regime is approximately realized for rather dense coacervates. Using the mean-field variant of the density functional theory, we calculate the surface tension (surface free energy) of the "coacervate-solvent" interface as a function of the bulk polymer concentration. Obtained results can be used to estimate the parameters of the polymer chains needed for practical applications such as drug encapsulation and delivery, as well as the design of adhesive materials.

Oxide powder mixture with poly-vinyl alcohol (PVA) and added polyethylene glycol (PEG) as plasticizer

Powder mixture consisted of ZnO, Mn2O3 (MnCO3) and Fe2O3 blended powders, was found laminating during compaction. Polyvinyl alcohol (PVA) and a combination of PVA with polyethylene glycol (PEG) added as a plasticizer, were introduced as polymer binders to improve the compaction of oxide mixtures. It has been done by forming a suspension of oxide mixture and varying the polymer solution concentration and composition. By evaporating the solvent, new materials were obtained, which consist of oxide particles bound via polymer. In such a manner obtained hybrid materials were characterized with attenuated total reflection Fourier transformed infrared (ATR-FTIR) spectroscopy, differential thermal analysis (DTA) and transmission electron microscopy (TEM). The oxide polymer material was compacted at 200 MPa and the expansion of this compact during heating was monitored in temperature range up to 550?C with dilatometer. It was found that PVA forms graft polymer with PEG and specific interaction with oxide particles surface was revealed.

Study on the Viscosity Optimization of Polymer Solutions in a Heavy Oil Reservoir Based on Process Simulation

Polymer flooding has been proved by many scholars for use in heavy oil reservoirs. However, due to mobility control effects and injectivity, selecting the appropriate solution viscosity is essential. It is difficult to form a deep understanding of the effect and mechanism of polymer flooding using conventional experimental methods with oil recovery as the reference standard, so it is necessary to conduct further study with the aid of simulation methods. In this study, a one-dimensional displacement mathematical model based on the Buckley–Leverett theory was established, and in the range of water–oil viscosity ratio from 0.1 to 0.6, the variation of water saturation along the flow caused by polymer solution was studied. The research results showed that under the action of a polymer solution, compared with water flooding, there was a decreasing region of water saturation along the flow due to oil phase accumulation. The larger the water–oil viscosity ratio, the larger the area of water saturation decline and the greater the degree of water saturation decline, resulting in a better the displacement effect. However, under the condition of oil–phase viscosity of 70 mPa·s, when the water–oil viscosity ratio reached 0.4, the range and degree of water saturation decline along the way no longer changed, all the crude oil that could be swept had been displaced, and the outlet end was close to producing only water, not oil; therefore, further increasing the water–oil viscosity ratio could not increase the oil recovery. At the same time, the increase in pressure had not changed, that is, the increase in pressure had not resulted in the same increase in oil recovery. When the viscosity of oil phase increased to 140 mPa·s, the same rule was displayed, the appropriate water–oil viscosity ratio was also 0.4. The paper analyzed the action mechanism of polymer solution through process description, and the results provided a clear selection method for selecting reasonable polymer solution concentration, as well as a reference for polymer solution range under different crude oil viscosity conditions.

A recyclable UCST-type biocatalyst to catalyze H2O2 degradation of phenol

Horseradish peroxidase (HRP) is a kind of enzyme commonly used in clinical trials that is rich in the plant horseradish. It has a wide range of applications in the fields of pharmacy and pollution control. However, free enzymes are easily denatured and inactivated by environmental influences, which is not conducive to the normal progress of the reaction. At the same time, the cost of enzymes is relatively high, and it is difficult to separate and recover during the reaction. In this study, the UCST-type temperature- responsive polymer was combined with HRP under the optimal immobilization reaction conditions of 3% polymer solution concentration, 60 ℃, and pH= 8 through affinity interaction to produce UCST-type smart polymerase. The smart polymerase has stronger temperature stability, pH stability and storage stability than free enzymes. In the simulated pollutant degradation experiment, under the molar ratio of phenol to H2O2 is 1:1, the temperature of 60 ℃, and pH= 7, smart polymerase can degrade 91% of phenol in a 100 mg/L phenol solution within 1 h. After five cycles of catalytic reaction, 68% of smart polymerase was recovered through cooling precipitation. In the phenol degradation experiments of two different real water samples, 88% and 90% of the phenol in the water were removed, respectively, and most of the highly active immobilized enzymes were recovered at the same time. Finally, the biotoxicity of the catalyzed reaction product is significantly reduced was demonstrated.

Efficient Cyclization of Linear Polymer with Pseudopolyrotaxane Assistance

The physical properties of cyclic polymers differ from those of linear polymers. To prepare cyclic polymers, the ends of a linear polymer must intramolecularly react. Cyclic polymers are typically synthesized at low concentration because intermolecular linkage is preferential to intramolecular linkage at high concentrations. Therefore, preparation of cyclic polymers at high concentrations is difficult. This study demonstrates a new approach to obtain cyclic polymers from highly concentrated polymer solutions using pseudo-polyrotaxanes (pPRxs). Cyclic polymers are prepared by penetrating a linear polymer into the cavity of a cyclic host to form pPRx and then the ends of the linear polymer are subsequently connected. Our approach allows the synthesis of cyclic polymers at concentration that do not allow conventional cyclic polymer synthesis. Specifically, although without pPRx, almost no cyclic polymers were obtained (<1%), with pPRx, the cyclic polymer was obtained as the main product (proportion of cyclic PEG 14%).

INCREASING EFFICIENCY OF THE DISPLACEMENT OF HIGHLY RESINOUS OILS BY POLYMER SOLUTIONS

The article presents the experimental results of studies of the filtration properties of oils from fields with a high content of asphaltene-resinous substances. Experimental studies of the filtration process of deposits with a high content of asphaltene-resinous substances have established that in low-permeability, unlike high-permeability reservoirs, the beginning of filtration proceeds according to a nonlinear law, and with an increase in the pressure gradient, the nonlinearity turns into a straight line corresponding to the Darcy law. In addition, the results of experimental studies on the displacement of oil from fields with a high content of asphaltene-resinous substances by polymer solutions on artificially created reservoir models are presented to determine the concentration of the polymer solution and the size of the slug to increase oil recovery from reservoirs. Experimental research on oil displacement by polymeric solutions were carried out on reservoir models filled with quartz sand, while the analyzed deposits are represented by carbonate limestone rocks. The results obtained on the oil displacement by polymer solutions on reservoir models with terrigenous reservoirs are considered possible for use on objects with carbonate reservoirs with a qualitative justification for the introduction of the polymer flooding method. Experimental studies on the oil displacement from fields with a high content of asphalteneresinous substances with a thickened water rim have established that this method gives the greatest increase in anhydrous and ultimate oil recovery, within a change in the concentration of the polymer solution of 0.2-0.4%, with a rim size of more than 70% of the oil-saturated reservoir volume. Studies on the displacement of high-viscosity oils with polymer solutions have shown that the use of this method of increasing the oil recovery factor in practice is not always economically feasible, due to the need to provide high injection pressures and a high concentration of an expensive polymer solution.

Pursuing Phase Transitions of a Concentrated Polymer Solution by In Situ Fluorescence Measurements Based On Aggregation-Induced Emission.

Concentration-dependent phase transitions in concentrated solutions have remained speculation due to the serious impediment of macromolecule dynamics by intensive topological entanglement or intermolecular interaction as well as the absence of powerful tool for detecting changes in chain or segment movement. Herein, taking a general polymer, namely, poly(vinyl alcohol) (PVA), as an example, a water-soluble fluorescent molecule with aggregation-induced emission (AIE) is introduced into the PVA solutions as a chain dynamics indicator to investigate phase transitions at high concentrations through in situ monitoring of the solvent evaporation process. Two turning points of fluorescent intensity are observed for the first time at mean concentrations of ∼25% and ∼45%, corresponding to the gelation and amorphous-to-crystalline transitions, respectively. Our work offers a fundamental insight into the physical nature of concentrate-dependent nonequilibrium transitions and develops a reliable and sensitive approach based on the AIE phenomenon for following high-concentration-triggered property changes of a polymer solution.

(Invited) Atmospheric Pressure Plasma-Assisted Electrospinning of Bead-Free Honeycomb-Patterned Nanofibers Via a Controlled Self-Assembly-Driven Phenomenon

The end of the 20th century has marked an enormous surge of interest in electrospinning after discovering its capacity of generating fibers from various polymers. This technique has actually shown several attractive strengths such as its versatility, affordability, simplicity and ability to adjust the diameter of the electrospun fibers from hundreds of micrometers down to tens of nanometers. The large surface area to volume ratio and high porosity of electrospun structures have rendered the technology appealing in numerous applications e.g. optical devices, catalyst supports, batteries, textiles and sensors. Moreover, electrospun fibers are very promising candidates in tissue engineering applications given their biomimicry of the natural extracellular matrix. The massive research advances in electrospinning have even led to the generation of fascinating bioinspired-patterned fibrous structures such as the lotus leaf, feather, silver ragwort leaf, spider web, plant tendril, bear hair and honeycomb. In particular, honeycomb-patterned nanofibrous structures are potentially very promising as tissue engineering scaffolds as they exhibit, in addition to the large surface area, a high structural stability and an architecture integrating interconnected microporous voids with nanofibers. Such structures were as such shown to synergistically promote the uniform infiltration of cells and their adhesion, proliferation and differentiation thus creating a stimulating microenvironment for the regeneration of different tissues such as blood vessel and bones. In fact, the geometry of the honeycombs also mimics the natural microvascular network and the spongy structure of the bone tissue. Interestingly, some research groups have introduced the possibility of electrospinning honeycomb-patterned nanofibers in a simple and rapid way by carefully varying some process parameters such as the polymer solution concentration and applied voltage without even the use of a sophisticated patterned collector. Actually, at a sufficiently low concentration, wet and still charged nanofibers can be deposited on the collector and can subsequently self-assemble into honeycomb structures via competitive actions between: 1) the surface tension that drives the fibers to merge together at a cross point and 2) the electrostatic repulsion that, in contrast, pushes adjacent sections away to form polygonal channels with three-branched walls. Polyacrylonitrile, polyvinyl alcohol, polyethylene oxide, polyurethane and polycaprolactone (PCL) were reported to be successfully electrospun into honeycomb structures via a self-assembly-driven phenomenon. Nonetheless, the low solution concentrations used to trigger this self-assembly have always led, in all the reported results so far, to the formation of beaded poor-quality nanofibers. In order to overcome this issue and obtain for the first time in literature bead-free fibrous honeycomb structures, the present work aimed at performing a pre-electrospinning treatment of a PCL solution by a non-thermal plasma generated directly inside the solution itself. To do so, a distinctive atmospheric pressure plasma reactor engendering a plasma jet with an afterglow in contact with the solution was designed in-house and was used with argon as working gas. This treatment is expected to trigger a plasma-induced degradation of the solvent molecules generating new species such as HNO3 and HCL thus enhancing the solution conductivity and the polymer electrospinnability. An extensive parametric study of the electrospinning process was first conducted with different solvents systems (chloroform/dimethylformamide (DMF) 4/1, dichloromethane (DCM)/DMF 4/1, DCM/DMF 3/2 and formic acid/acetic acid 9/1), PCL molecular weights (80000, 45000 and 37000 g/mol), polymer concentrations (ranging from 6 to 20% w/v), applied voltages and tip-to-collector distances. Concurrently, the operational plasma parameters (gas flow rate, applied voltage and plasma exposure time) were delicately tailored to treat the different solutions prior to the electrospinning. Results revealed that the solvent system chloroform/DMF 4/1, a PCL weight of 37000 g/mol, a PCL concentration of 17.5% w/v, an applied voltage of 22.5 kV and a tip-to-collector distance of 15 cm led to an optimal self-assembly of the PCL fibers into a clear honeycomb pattern as visualized by scanning electron microscopy images. Moreover, for all the used electrospinning parameters, a pre-plasma treatment of the solution triggered a significant enhancement in the fibers quality with less to no beads. In particular, a plasma treatment time of 15 s, argon flow rate of 0.5 slm and applied voltage of 3 kV combined with the pre-mentioned optimal electrospinning parameters resulted in well-balanced morphology combining a honeycomb pattern with bead-free fibers. Overall, this work introduces a novel interesting application of atmospheric pressure plasma treatment illustrated by the generation of high-quality bead-free honeycomb-patterned nanofibrous structures. Figure 1

Optimal Hardenability Steel and Its Future Worldwide Application

In the paper the problem of intensive quenching (IQ) of optimal hardenability (OH) steel in low concentration of water solutions that eliminates film boiling is widely discussed. Currently, for performing IQ processes complicated quench systems and highly costly technological processes are used resulting in the slow application of IQ technologies in the heat-treating industry. Also, there is no complete understanding of what makes OH steel unique, especially after quenching in low concentrations of water polymer solutions. The paper states that OH steel should be quenched in water polymer solutions of low concentration (1%–3%) agitated by hydrodynamic emitters to guarantee the absence of the film boiling process. Optimal results one can obtain if OH steel is composed according to patented methodology and is quenched in condition 0.8≤Kn≤1. All of this simplifies the quenching process resulting in acceleration and wide use of IQ technologies in the heat-treating industry.

Electrospun polyacrylonitrile fibrous membrane for dust removal

Particulate matter (PM) pollution has become a serious threat to human health. Accordingly, an air filtration media that can efficiently remove particulate matter should be developed immediately. Nanofibrous membrane filter prepared by electrospinning technology has nanoscale diameter, high specific surface area, and relatively high porosity, which are suitable for dust removal. This paper explored the effects of electrospinning parameters on the microscopic morphology, fiber diameter, and pore size of polyacrylonitrile (PAN) nanofibrous membranes, including polymer solution concentration, applied voltage, and tip-to-collector distance. Thereafter, filtration efficiencies of electrospun PAN fibrous membrane and Polytetrafluoroethylene (PTFE), Cellulose acetate (CA), Nylon commercial filter were compared by removing smoke PMs. Results showed that fiber diameter and pore size increase with increasing concentration but decrease with increasing distance. With an increase in applied voltage, fiber diameter and pore size first decreased and increased thereafter. Lastly, filtration experimental results showed that filtration efficiency of electrospun PAN nanofibrous membranes was higher than that of those commercial filter membranes for ultra fine dust (0.3–0.5 μm).

Electrospinning of Poly (Acrylamide), Poly (Acrylic Acid) and Poly (Vinyl Alcohol) Nanofibers: Characterization and Optimization Study on the Effect of Different Parameters on Mean Diameter Using Taguchi Design of Experiment Method.

In this study, nanofibers of poly (acrylic acid) (PAAc), polyacrylamide (PAAm) and poly (vinyl alcohol) (PVOH) were prepared using the electrospinning technique. Based on the Taguchi DOE (design of experiment) method, the effects of electrospinning parameters, i.e., needle tip to collector distance, polymer solution concentration, applied voltage, polymer solution feed rate and polymer type, on the diameter and morphology of polymer nanofibers were evaluated. Analyses of the experiments for the diameters of the polymer nanofibers showed that the type of polymer was the most significant factor. The optimal combination to obtain the smallest diameters with minimum deviations for electrospun polymer nanofibers was also determined. For this purpose, the appropriate factor levels were determined as follows: polymer PAAm, applied voltage 10 kV, delivery rate 0.1 mL/h, needle tip to collector distance 10 cm, and polymer solution concentration 8%, to obtain the thinnest nanofibers. This combination was further validated by conducting a confirmation experiment, and the average diameter of the polymer nanofibers was found to be close to the optimal conditions estimated by the Taguchi DOE method.

A proof of concept to define the parameters affecting poly-l-lactide-co-poly-ε-caprolactone shape memory electrospun nanofibers for biomedical applications

This study is a proof of concept performed to evaluate process parameters affecting shape memory effect of copolymer poly-l-lactide-co-poly-ε-caprolactone (PLA:PCL) 70:30 ratio based nanofibrous scaffolds. A design of experiment (DOE) statistical approach was used to define the interaction between independent material and process variables related to electrospun scaffold manufacturing, such as polymer solution concentration (w/v%), spinning time (min), and needle size (Gauge), and their influence on Rf% (ability of the scaffold to maintain the induced temporary shape) and Rr% (ability of the scaffold to recover its original shape) outputs. A mathematical model was obtained from DOE useful to predict scaffold Rf% and Rr% values. PLA-PCL 15% w/v, 22G needle, and 20-min spinning time were selected to confirm the data obtained from theoretical model. Subsequent morphological (SEM), chemical-physical (GPC and DSC), mechanical (uniaxial tensile tests), and biological (cell viability and adhesion) characterizations were performed.Graphical abstract

Optimization of the electrospun-aligned microfiber composite with liquid crystal for terahertz wave variable phase shifters

AbstrcatIn this study, electrospun microfibers (MFs) were produced and used as key materials to optimize the composite with liquid crystal (LC) for terahertz (THz) wave phase shifters. These MFs, with an average diameter of 1.4 μm, were produced using the polymer solution concentration of 14 wt% and spinning voltage of 13 kV. When MFs were combined with LC, the measured results of the electrical characteristics showed that 14 wt% MFs provided an outstanding solution to the problem of a significant reduction in the natural birefringence of pure LC. The birefringence in the THz frequency range of the composite using 14 wt% MFs approached 90% compared with that using pure LC. Additionally, the decay time drastically shortened from hundreds of seconds for pure LC to hundreds of milliseconds for MF/LC composite and was independent of device thickness.

Nano-Sized Polyelectrolyte Complexes Formed between Poly(vinyl benzyl trimethyl ammonium chloride) and Insulin

Novel biohybrid homo-polyelectrolyte-based nanocarriers were formed by the complexation of insulin (INS) with a biocompatible and cationic polyelectrolyte, namely, poly(vinyl benzyl trimethylammonium chloride) (PVBTMAC). According to light-scattering techniques, the hydrophilic PVBTMAC homo-polyelectrolyte forms single chains in aqueous media. The resulting biohybrid PVBTMAC/INS nanocarriers were formed via electrostatic co-assembly. The effects of polyelectrolyte structure and content on the characteristics of the formed PVBTMAC/INS complexes were studied. A significant aggregation tendency of the PVBTMAC/INS complexes was observed, based on the physicochemical results, especially at high protein concentration, corroborating the effective electrostatic interaction of INS with the cationic polyelectrolyte. The physicochemical properties of the formed PVBTMAC/INS nanocarriers depended on the concentration of the stock polymer and INS solutions. A neat PVBTMAC homo-polymer and PVBTMAC/INS nanocarriers demonstrated good serum stability in the presence of fetal bovine serum (FBS) proteins. Fluorescence spectroscopy (FS) studies revealed no INS conformational changes after its complexation with the cationic PVBTMAC polyelectrolyte. The obtained PVBTMAC/INS complexes demonstrated considerable and promising characteristics for potential use as insulin delivery systems.

Electrosprayed Nanoparticles Containing Hydroalcoholic Extract of Echinacea purpurea (L.) Moench Stimulates Immune System by Increasing Inflammatory Factors in Male Wistar Rats.

Purpose: Echinacea purpurea (L.) Moench is a member of the Asteraceae family and is traditionally used mainly due to its immunostimulatory properties. Various compounds including alkylamides and chicoric acid were reported as active ingredients of E. purpurea. Here, we aimed to prepare electrosprayed nanoparticles (NPs) containing hydroalcoholic extract of E. purpurea using Eudragit RS100 (EP-Eudragit RS100 NPs) to improve the immunomodulatory effects of the extract. Methods: The EP-Eudragit RS100 NPs with the different extract:polymer ratios and solution concentrations were prepared using the electrospray technique. The size and morphology of the NPs were evaluated using dynamic light scattering (DLS) and field emission-scanning electron microscopy (FE-SEM). To evaluate the immune responses, male Wistar rats were administrated with the prepared EP-Eudragit RS100 NPs and plain extract in the final dose of 30 or 100 mg/kg. The blood samples of the animals were collected and the inflammatory factors and complete blood count (CBC) were investigated. Results: In vivo studies indicated that the plain extract and EP-Eudragit RS100 NPs (100 mg/kg) significantly increased the serum level of tumor necrosis factor-α (TNF-α) and interleukin 1-β (IL1-β) whereas the EP-Eudragit RS100 NPs (30 mg/kg) significantly increased the number of white blood cells (WBCs) compared to the control group. Lymphocytes' count in all groups was increased significantly compared to the control group (P<0.05) whereas other CBC parameters remained unchanged. Conclusion: The prepared EP-Eudragit RS100 NPs by electrospray technique caused significant reinforcement in the immunostimulatory effects of the extract of E. purpurea.

Construction of porous poly (l-lactic acid) surface via carbon quantum dots-assisted static Breath-Figures method

Focused on the design and construction of surface porous morphology of poly (L-lactic acid) membrane. A bottom-up surface patterning technique, static Breath-Figures method, combined with Pickering emulsion mechanism is regulated to fabricate porous poly (L-lactic acid) membrane surface rapidly and reliably. Carbon quantum dots, synthesized in an environment-respecting route, are used to assist the formation of droplet templates. The dimensions and morphology of surface pores can be controlled in a wide range by simply adjusting the content of carbon quantum dots and polymer solution concentration. The effect of the crystallization ability of the adsorption layer formed at the interface between the polymer solution and the water droplet on the pore dimension is proposed. Furthermore, PLLA can be completely degraded by CQD carboxyl catalysis. In brief, we have successfully manufactured a biocompatible PLLA/CQD membrane with a surface porous microstructure which may be potentially applied in cell culture and cell-related research. Compared to previous literature, this work develops a new one-step template patterning method with dynamic controllability. This work also avoids limitations such as high humidity, flowing airflow, and amphiphilic surfactants compared to traditional Breath-Figure approaches.

Comparison of the change in viscosity of a polyvinyl alcohol solution by adding Polyethylene glycol and Polyvinylpyrrolidone to solutions of Polyvinylalcohol

The aim of this research is to improve the flow properties of polymers, in particular viscosity, by mixing polymers to be use in various fields. Samples prepared by stirring polyvinyl alcohol on fire for half a second in a fixed weight ratio with divergent weight ratios of polyethylene glycol and polyvinylpyrrolidone, both separately. Other samples were prepared in the same way by mixing the three polymers followed by measuring the molecular weight of all the samples. This method of preparation made the polymers insoluble in water, therefore nitric acid was used to dissolve them. Flow time of the solvent and all solutions were measured, which was used to calculate the viscosities, It has been shown that these viscosities increase with increasing concentrations of polymers in solutions by establishing a positive relationship between them, It was found that the intrinsic viscosity decreases with increasing concentrations after being graphed using intrinsic viscosity calculations from the relationship between specific viscosity and relative viscosity logogram with concentration. These results may be used in industrial medical applications as well as scientific studies.