Basis Of Poly Research Articles

Properties of chromatographic columns prepared on the basis of poly(1-trimethylsilyl-1-propyne) modified with organic bases

This article describes the effect of modification with organic bases such as uracil (U) and polyethyleneimine (PEI) on the adsorption and chromatographic properties of poly(1-trimethylsilyl-1-propyne) (PTMSP) used as a stationary phase (SP) in packed and capillary columns. It was shown that the sorbents prepared on the basis of diatomite Chromosorb P NAW support and successively modified with 9 wt.% PTMSP and 1 wt.% U (or PEI) (PC-U and PC-PEI samples, respectively), have a mesoporous structure. The IR spectrum shows the presence of carbonyl groups in the sorbent modified with uracil. The impregnation of the Chromosorb P NAW + (9/1) wt.% PTMSP sorbent with a polyethyleneimine solution leads to the appearance in the spectrum of bands characterizing NH stretching and bending vibrations, as well as a band at 1310 cm−1 which can be attributed to CN bond vibrations. The chromatographic properties of the studied sorbents differ significantly from the properties of the initial PTMSP. Packed columns PC-U and PC-PEI, as well as capillary columns with a polyethyleneimine-modified PTMSP layer, allow one to selectively separate mixtures of polar and non-polar compounds and structural isomers of hydrocarbons. Methanol on these columns is eluted in the form of a symmetrical peak separately from propane, propylene and other associated hydrocarbon impurities in commercial (technical, target) n-butane.

Electrochemical DNA Sensor for Valrubicin Detection Based on Poly(Azure C) Films Deposited from Deep Eutectic Solvent.

A novel electrochemical DNA sensor was developed for the detection of the anthracycline drug, valrubicin, on the base of poly(Azure C) electropolymerized from the deep eutectic solvent reline and covered with adsorbed DNA from calf thymus. Biosensor assembling was performed by multiple scanning of the potential in one drop (100 µL) of the dye dissolved in reline and placed on the surface of a screen-printed carbon electrode. Stabilization of the coating was achieved by its polarization in the phosphate buffer. The electrochemical characteristics of the electron transfer were determined and compared with a similar coating obtained from phosphate buffer. The use of deep eutectic solvent made it possible to increase the monomer concentration and avoid using organic solvents on the stage of electrode modification. After the contact of the DNA sensor with valrubicin, two signals related to the intrinsic redox activity of the coating and the drug redox conversion were found on voltammogram. Their synchronous changes with the analyte concentration increased the reliability of the detection. In the square-wave mode, the DNA sensor made it possible to determine from 3 µM to 1 mM (limit of detection, 1 µM) in optimal conditions. The DNA sensor was successfully tested in the voltammetric determination of valrubicin in spiked artificial urine, Ringer-Locke solution mimicking plasma electrolytes and biological samples (urine and saliva) with a recovery of 90-110%. After further testing on clinical samples, it can find application in the pharmacokinetics studies and screening of new drugs' interaction with DNA.

The Effect of Complex Modifier Consisting of Star Macromolecules and Ionic Liquid on Structure and Gas Separation of Polyamide Membrane.

A novel hybrid membrane was developed on the basis of poly(m-phenylene isophthalamide) (PA) by introducing an original complex modifier into the polymer; this modifier consisted of equal amounts of heteroarm star macromolecules with a fullerene C60 core (HSM) and the ionic liquid [BMIM][Tf2N] (IL). The effect of the (HSM:IL) complex modifier on characteristics of the PA membrane was evaluated using physical, mechanical, thermal, and gas separation techniques. The structure of the PA/(HSM:IL) membrane was studied by scanning electron microscopy (SEM). Gas transport properties were determined by measuring He, O2, N2, and CO2 permeation through the membranes based on PA and its composites containing a 5 wt% modifier. The permeability coefficients of all gases through the hybrid membranes were lower than the corresponding parameters for the unmodified membrane, whereas the ideal selectivity in the separation of He/N2, CO2/N2, and O2/N2 gas pairs was higher for the hybrid membrane. The position of the PA/(HSM:IL) membrane on the Robeson's diagram for the O2/N2 gas pair is discussed.

Enhancing Performance of LiFePO4 Battery by Using a Novel Gel Composite Polymer Electrolyte

Composite polymer electrolyte (CPE) is expected to have great prospects in solid-state batteries. However, their application is impeded due to the poor interfacial compatibility between CPE and electrodes that result in sluggish ionic transformation, especially at low temperatures. Here, on the basis of Poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) polymer electrolyte, gel composite polymer electrolyte (GCPE) with fast Li+ transport channel is prepared by in-situ polymerization with poly (ethylene glycol) methyl ether acrylate (PEGMEA) monomer and FEC as additive. Compared with CPE, GCPE increases the ionic conductivity by 10 times. It also achieves more uniform lithium precipitation and significantly inhibits the growth of lithium dendrites. The LFP/GCPE/Li battery has a capacity retention of over 99% at both room temperature and 0 °C after 100 cycles. In addition, the coulombic efficiency is above 99% during cycling. Our work provides a new technology to prepare GCPE with high ionic conductivity at both room temperature and low temperatures that has great potential in the application of solid-state lithium batteries.

Efficient conversion of CO2 into cyclic carbonates under atmospheric by halogen and metal-free poly(ionic liquid)s

A novel series of halogen free, hydroxyl group containing poly(ionic liquid)s (PILs) was first synthesized from glycerol dimethyl acrylate (GDA) and 1-vinyl imidazole (1-VIM) through free radical polymerization, follow by an alkylation step and an ion-exchange procedure to form the final imidazolium hydrogen carbonate heterogenous catalyst poly(HCO3-OH-n). The chemical and physical properties were investigated by varying the monomer ratio between GDA and 1-VIM. Among them, poly (HCO3-OH-2) exhibited the highest catalytic activity for CO2 cycloaddition, with the yield of chloropropene carbonate 90% under mild conditions (80 °C, 0.1 MPa, 12 h, 0.15 g catalyst for 32 mmol epichlorohydrin) in the absence of any cocatalyst, metal or solvent. A range of substrates with good to excellent yields under atmosphere was obtained. The poly(HCO3-OH-n) catalyst is collectable and still remains acceptable catalytic activity after six runs. Finally, a preliminary kinetic is calculated on the basis of poly(HCO3-OH-2) with the activation energy value of 79.5 kJ·mol−1. This study highlights that the poly(HCO3-OH-n) enable to reach efficient CO2 conversion under mild conditions.

PVA–Polystyrene-Based Polymer Films with Water-Induced Shape-Memory Effect

In this work, a series of novel water-induced shape-memory composite films are prepared on the basis of poly(vinyl alcohol)-polystyrene (PVA–PSX) through one pot in situ polymerization method. The neat PVA film is modified to PVA–PSX film by loading calibrated amount of styrene, and the resulted film exhibits high mechanical strength (tensile strength ∼40 MPa, tensile strain ∼315%, Young’s modulus ∼0.25 MPa and toughness ∼5 MJ/m3). More importantly, water-induced shape-memory behavior is observed for the PVA–PSX composite films and among various proportions, PVA–PS3 film (3 v/v% of styrene content) shows the fastest shape recovery rate (160 s). The relative low value of storage modulus and glass transition temperature of the PVA–PS3 films is attributed to water-induced shape recovery. The desirable and multifaceted properties of the PVA–PSX composite film, such as optimum transparency, improved water resistance, enhanced shape recovery, diminished UV-light transmission, and effectual antimicrobial activity, propound that the composite film is a suitable candidate for preparing packaging materials in food and cosmetic industries.

Bi-layered nanofibrous membrane with osteogenic and antibacterial functions for periodontal tissue regeneration.

Guided tissue regeneration (GTR) membranes have great potential to promote periodontal tissue regeneration and reestablishment. However, the regeneration potential and microbial infection resistance of current GTR membranes still need to be improved. Here, a bi-layered nanofibrous membrane on the basis of poly (lactic-co-glycolic acid) (PLGA)/gelatin with osteogenic and antibacterial functions was fabricated for periodontal tissue regeneration. The antimicrobial layer (AL) of the bi-layered nanofibrous membrane was composed of nanofibrous PLGA/gelatin nanofibers loaded with nano-silver (nAg), while the osteoconductive layer (OL) of the nanofibrous membrane consisted of PLGA/gelatin nanofibers loaded with nano-hydroxyapatite (nHA). The bi-layered nanofibrous membrane was examined by scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), transmission electron microscope (TEM), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectrometry (XPS) and X-ray diffractometry (XRD). The results showed that nHA and nAg particles were well evenly loaded or embedded in PLGA/gelatin nanofibers. The cell culture experiments suggested that the bi-layered nanofibrous membrane possessed good cytocompatibility and the OL of the bi-layered nanofibrous membrane possessed an enhanced osteogenic capacity for human osteoblast-like cells (MG63), which was verified by the good cell viability and the increased alkaline phosphatase (ALP) activity, respectively. The results of in vitro antimicrobial study displayed that the AL of the bi-layered nanofibrous membrane possessed an effective antibacterial capability. In conclusion, the prepared bi-layered nanofibrous membrane with osteogenic and antibacterial functions may have great potential for periodontal tissue regeneration and reestablishment.[Formula: see text].

Influence of the Alkali Treatment of Flax and Hemp Fibers on the Properties of PHBV Based Biocomposites.

This study assessed the impact of alkali treatment of hemp and flax fibers on mechanical properties (determined by means of the uniaxial tensile test, impact tensile strength test and hardness test), processing properties (the course of the extrusion and injection process) and usable properties (shrinkage of molded pieces, degree of water absorption) of biocomposites on the base of poly (3-hydroxybutyric-co-3-hydroxyvaleric acid) (PHBV) biopolymer. For this purpose, 1 mm of length flax and hemp fibers was surface-modified by means of aqueous solution of NaOH (sodium hydroxide) with concentrations of 2%, 5% and 10%. The composites were made using the extrusion technology. The test specimens were produced by injection molding technology. In total, eight types of biocomposites with modified and non-modified fibers were produced, and each biocomposite contained the same filler content (15 wt.%). Their properties were compared in some cases with pure PHBV polymer. In the case of biocomposites filled with hemp fibers, it was noted that an increase of the alkalizing solution concentration improved most of the tested properties of the obtained biocomposites. On the other hand, in the case of flax fibers, there was a significant decrease in most of the mechanical properties tested for the composite containing fibers etched by 10% NaOH solution. The obtained results were verified by examining fibers and the destroyed specimens with a scanning electron microscope (SEM) and an optical microscope, which confirmed, especially, the significant geometry changes of the flax fibers etched by 10% NaOH solution. This procedure also resulted in a significant change of processing properties—a composite of this fiber type required about 20 °C lower temperature during the extrusion and injection molding process in order to obtain the right product. These results lead to the important conclusion that for each filler of the plant-origin and polymer matrix, the fiber alkalization method should be selected individually in order to improve the specific properties of biocomposites.

ДОСЛІДЖЕННЯ ФІЗИЧНОЇ МОДИФІКАЦІЇ ПОЛІЛАКТИДІВ

The physical modification of poly(lactiс acid) materials suitable for use in the form of films for the packaging industry and paper lamination has been studied. Modification of poly(lactiс acids) of different degrees of crystallinity with glycerol was performed. The peculiarities of the formation of film materials on the basis of poly(lactiс acids) and their mixtures with glycerin are investigated, the choice of the optimal solvent (chloroform) for the formation of films by irrigation is substantiated and carried out. Concentration and temperature-time characteristics of formation of modified poly(lactiс acid) films are determined. On the basis of the performed researches the main stages of manufacturing of modified poly(lactiс acid) films are substantiated and their physical and mechanical properties are investigated.

Rheological and Adhesion Properties of Hot-Melt Adhesives Based on Hydrocarbon Resins and Poly(ethylene-vinyl acetate)

Polymer hot-melt adhesives are obtained on the basis of poly(ethylene-vinyl acetate), polyethylene wax, and aromatic (C9) hydrocarbon resins differing in the degree of hydrogenation of aromatic groups (from 0 to 37%). The content of poly(ethylene-vinyl acetate) is varied from 30 to 80%, and the concentration of other components of the adhesive is within 10–35%. The rheology of adhesive components and blend compositions is studied in detail, and the adhesion characteristics of the adhesives are determined. It is found that the use of a nonhydrogenated resin leads to high adhesion properties of the adhesive but imparts viscoplasticity to it. The use of a hydrogenated resin provides better rheological properties of the adhesive, but a higher content of poly(ethylene-vinyl acetate) is required to achieve good adhesion characteristics.

The Drug-Loaded Electrospun Poly(ε-Caprolactone) Mats for Therapeutic Application.

Diclofenac sodium salt (DSS)-loaded electrospun nanofiber mats on the base of poly(ε-caprolactone) (PCL) were investigated as biocompatible nanofibrous mats for medical applications with the ability to inhibit bacterial infections. The paper presents the characteristics of fibrous mats made by electrospinning and determines the effect of medicament on the fiber morphology, chemical, mechanical and thermal properties, as well as wettability. PCL and DSS-loaded PCL nanofibrous mats were characterized using scanning electron microscopy, transmission electron microscopy, attenuated total reflectance-Fourier transform infrared spectrometry, dynamic mechanical analysis, and contact angle measurements. Electron paramagnetic resonance measurements confirmed the lifetime of DSS before and after application of high voltage during the electrospinning process. In vitro biocompatibility was studied, and it was proved to be of good viability with ~92% of the diploid human cells culture line composed of lung fibroblast (MRC 5) after 48 h of incubation. Moreover, the significant activity of DSS-loaded nanofibers against cancer cells, Ca Ski and HeLa, was established as well. It was shown that 12.5% (m/V) is the minimal concentration for antibacterial activity when more than 99% of Escherichia coli (Gram-negative) and 99% of Staphylococcus aureus (Gram-positive) have been exterminated.

Functional Polylactide Blend Films for Controlling Mesenchymal Stem Cell Behaviour.

Polymer blending is a suitable physical modification method to create novel properties of different polymers. Blending polylactic acid (PLA) and polyethylene glycol (PEG) produces materials with a wide range of properties. This study was the first to investigate the effect of different isomeric forms of PLA and PEG with terminal amino groups to obtain biocompatible films for human mesenchymal stem cell cultivation. It has been shown by scanning electron microscopy that the surface topology changes to the greatest extent when using films obtained on the basis of poly(d,l-lactide) and PEG with high molecular weights (15,000 g/mol). In order to obtain thin films and rapid evaporation of the solvent, PEG is mixed with PLA and does not form a separate phase and is not further washed out during the incubation in water. The presence of PEG with terminal hydroxyl and amino groups in blend films after incubation in water was proven using Fourier transform infrared (FTIR) spectroscopy. Results of fluorescence microscopy demonstrated that blend films formed on PLA and polyethylene glycol diamine (PEG-NH2) are more suitable for cell spreading and focal contact formation compared to cells cultured on the surface of pure PLA films or films made from PLA and PEG.

Reactions of titanium alkoxide with SiH containing polymers as a route to titanium/siloxane hybrid materials with enhanced refractive index

Reactions of titanium tetrabutoxide with polyhydromethylsiloxane (PHMS) and with some hydromethylsiloxane copolymers were used for synthesis of light transparent materials having enhanced refractive index. The FTIR, 1H NMR and 29Si NMR spectroscopies were used to study the reaction between PHMS and titanium tetrabutoxide in toluene. Reaction of SiH functional siloxane polymers with titanium tetrabutoxide results in a titanium‐containing heterosiloxane prepolymers that are stable under anhydrous anaerobic conditions. Exposure of the resulting materials to humid air transforms them into light transparent titanium/siloxane nanocomposites with enhanced refractive index. The films of these composites formed during the spin‐coating process were characterized by UV–Vis, ellipsometry, IR and 29Si NMR spectroscopies and transmission electron microscopy (TEM). Titanium/siloxane hybrid films obtained on the basis of poly(phenylmethylsiloxane‐co‐hydromethylsiloxane) copolymer are free of cracks and have a refractive index of up to 1.60.

Контроль структуры имплантов и систем доставки лекарственных соединений при помощи метода сканирующей электронной микроскопии с энергодисперсионным анализом

Scanning electron microscopy (SEM) in combination with energy-dispersive spectrometric (EDS) analysis was used for the first time in the studies of composition of several materials being developed for medical uses. Cartilage implants were obtained on the basis of poly(acrylamide) hydrogels, bacterial and plant cellulose samples; dynamics of changes in implant composition and composition of near-boundary zones was demonstrated. This dynamics is indicative of dependence of osteointegration process on the nature of cellulose sample. The systems intended for protein delivery and based on porous vaterites (СаСО3) were studied; these delivery systems include the composite products in which the matrices (СаСО3 cores) are coated with several pairs of polyelectrolyte layers. It was demonstrated that structures of polyelectrolyte coatings can be determined depending on the coating methods; localization of encapsulated protein in СаСО3 cores was established.

Fibrillar biocomposite on the base of poly(3-hydroxybutyrate) nanofibers and iron oxide magnetic nanoparticles

The novel biodegradable biocomposites on the base of poly(3-hydroxybutyrare) nanofibers with embedded iron oxide nanoparticles have been studied by transmission electron microscopy (TEM), Mssbayer spectroscopy, small angle X‑ray scattering (SAXS), and macroscopic magnetization techniques.

Reversible Wettability Effect of the Organic-(≡TiO)<sub>n</sub>- Inorganic Terpolymers Surface

The optically transparent organic-inorganic terpolymers were obtained on the basis of poly (titanium oxide) and organic monomers of the vinyl series, characterized by the reversible wettability of the surface. The poly (titanium oxide) inside the material had a structure close to anatase and was uniformly distributed over the surface of the sample as it was determined by X-ray phase analysis and electron microscopy. A single-electron transition Ti4++ e ̅ → Ti3+ occurred in the samples under UV-irradiation accompanied by a breaking of the Ti-O bond and a decreasing of the terpolymers transparency from 90% to 20%; the process was reversible in time. The reversible of the samples surfaces from hydrophobic to hydrophilic were observed. The water wetting angle varied within 80 °↔ 5 ° range.

Removal of Methylene Blue from Aqueous Solutions Using Poly(vinyl alcohol)/Montmorillonite Nanocomposite Hydrogels: Taguchi Optimization

Nanocomposite hydrogel adsorbents on the basis of poly(vinyl alcohol) containing 0, 4, 8 and 12 wt% (based on dry basis) of montmorillonite were prepared using a cyclic freezing–thawing process. The capabilities of the adsorbents in adsorbing of a cationic dye, methylene blue, were studied in aqueous solutions having different temperatures, pH and concentrations. The Taguchi method was utilized to optimize the controllable factors, including the montmorillonite loading level, the solution temperature and pH and also the methylene blue concentration in adsorption solution. The prepared nanocomposite hydrogel adsorbents were characterized by Fourier transform infrared spectroscopy and their gel content and swelling values were also measured. The results showed that the gel content and swelling of nanocomposite hydrogel adsorbents had a direct and inverse dependency to the loading level of incorporated montmorillonite to adsorbent, respectively. The successful dye adsorption by the prepared nanocomposite hydrogel adsorbents was confirmed by the Fourier transform infrared spectroscopy. Based on the Taguchi method, the optimized conditions for methylene blue adsorption were found as: montmorillonite loading level of 12 wt%, adsorption temperature of 50 °C, pH of the aqueous solution of 9 and methylene blue concentration in adsorption solution of 5 mg/L. The percentage contribution of each parameter on the removal of methylene blue was determined using the Analysis of Variance method and the following order was found: temperature > concentration of methylene blue in solution > montmorillonite loading level in adsorbent > pH.

Composites of Poly (3,4-Ethylenedioxythiophene) with Nanostructures as Electrochemical Sensors for Application in Bioelectroanalysis

Background: The article presents the state of research on conductive composite materials constructed on the basis of poly (3,4-ethylenedioxythiophene) (PEDOT), a conductive polymer, as well as selected nanoparticles and nanostructures. Combining two or more materials in a composite which is later used in electrode modification can result in obtaining an electrode with new, more desirable properties. One of such fields is pharmacological analysis which, due to the continuous emergence of new substances and often also a need for analyte determination in complex samples, requires newer instruments in the form of suitably sensitive and selective sensors. Contents: The review contains the description of properties of PEDOT and composite PEDOT with polystyrenesulfonates. In the following part, composite materials are described: PEDOT-CNT, PEDOT- nanoparticles, PEDOT-graphene. The review closes with the examples of multi-component composite materials. Conclusion: The on-going development of new substances used in medicine, pharmacy and related fields, as well as the continuous increase in the production and consumption of this type of substances, necessitates constant development and modernization of analytical techniques used for their determination. : Biomedical assays require being able to carry out determinations in different systems, including in vitro ones, without separating individual compounds. It is necessary to be able to identify several substances simultaneously or determine one compound in the presence of chemically similar substances. Modern electrode materials such as PEDOT and nanostructured materials allow for the development of sensors which are getting increasingly better at meeting the requirements of the analysts.

Synthesis and investigation of copolymer properties on the basis of poly(ethylene glycol)fumarate and methacrylic acid

Synthesis and investigation of copolymer properties on the basis of poly(ethylene glycol)fumarate and methacrylic acid

Effect of Hard Segment Structure on the Thermomechanical Properties of Polyurethaneimides

New segmented polyurethaneimides containing poly(ethylene glycol adipate) soft segments and bis(urethaneimide) hard segments are synthesized. Copolymers are obtained on the basis of poly(ethylene glycol adipate) (Mn = 2.5 × 103) terminated with 2,4-toluene diisocyanate, two aromatic dianhydrides, and six aromatic diamines. The structure of the synthesized polymers is studied by IR and NMR spectroscopy. The thermal properties of the copolymers are characterized by TGA and DSC. Effects of hard segment length and substituent position in the diamine fragment on the thermal and mechanical properties of the polyurethaneimides are investigated.