CHANGE IN THE SURFACE STRUCTURE OF SEMICONDUCTOR POLYMER FILMS DURING REVERSE OXIDATION-REDUCTION

Методом растровой электронной микроскопии исследована морфология поверхности пленок полупроводниковых полимеров: полианилина, поли-о-толуидина, поли- α -нафтиламина. Пленки получены электрохимическим синтезом из подкисленных минеральными кислотами растворов их мономеров методом циклической вольтамперометрии. Пленки сформированы на платиновых подложках, сделанных по принципу биметаллических пластинок. Процессы обратимого окисления и восстановления полученных пленок осуществляли с применением электрического тока в водных растворах соляной кислоты, что приводило к допированию полимеров хлорид анионами. Показано, что поверхность пленок полианилина и поли-о-толуидина имеет схожую структуру, состоящую из многочисленных сферических зерен размером от 1 до 5 мкм. Поверхность пленок поли- α -нафтиламина существенно отличается и состоит из дендронов и крупных пор. При этом, во всех случаях наблюдаемые надмолекулярные образования для пленок в окисленном состоянии имеют несколько больший размер, чем для пленок в восстановленном состоянии, что обусловлено изменением конформации макромолекул. The surface morphology of films of semiconducting polymers: polyaniline, poly-o-toluidine, poly-α-naphthylamine was studied by scanning electron microscopy. The films were obtained by electrochemical synthesis from solutions of their monomers acidified with mineral acids by the method of cyclic voltammetry. The films are formed on platinum substrates made according to the principle of bimetallic plates. The processes of reversible oxidation and reduction of the obtained films were carried out using an electric current in aqueous solutions of hydrochloric acid, which led to the doping of polymers with chloride anions. It was shown that the surface of films of polyaniline and poly-o-toluidine has a similar structure, consisting of numerous spherical grains ranging in size from 1 to 5 pm. The surface of poly-α-naphthylamine films is significantly different and consists of dendrons and large pores. In this case, in all cases, the observed supramolecular formations for films in the oxidized state are somewhat larger than for films in the reduced state, which is due to a change in the conformation of macromolecules.

Bioactive Pectin-Murta (Ugni molinae T.) Seed Extract Films Reinforced with Chitin Fibers

This study investigated the biocomposite pectin films enriched with murta (Ugni molinae T.) seed polyphenolic extract and reinforced by chitin nanofiber. The structural, morphological, mechanical, barrier, colorimetric, and antioxidant activity of films were evaluated. The obtained data clearly demonstrated that the addition of murta seed extract and the high load of chitin nanofibers (50%) provided more cohesive and dense morphology of films and improved the mechanical resistance and water vapor barrier in comparison to the control pectin film. The antioxidant activity ranged between 71% and 86%, depending on the film formulation and concentration of chitin nanofibers. The presented results highlight the potential use of chitin nanofibers and murta seed extract in the pectin matrix to be applied in functional food coatings and packaging, as a sustainable solution.

Enhancement of the Antioxidant and Antimicrobial Activities of Porphyran through Chemical Modification with Tyrosine Derivatives

The chemical modification of porphyran hydrocolloid is attempted, with the objective of enhancing its antioxidant and antimicrobial activities. Sulfated galactan porphyran is obtained from commercial samples of the red algae Porphyra dioica using Soxhlet extraction with water at 100 °C and precipitation with isopropyl alcohol. The extracted porphyran is then treated with modified L-tyrosines in aqueous medium in the presence of NaOH, at ca. 70 °C. The modified tyrosines L1 and L2 are prepared through a Mannich reaction with either thymol or 2,4-di-tert-butylphenol, respectively. While the reaction with 2,4-di-tert-butylphenol yields the expected tyrosine derivative, a mixture of products is obtained with thymol. The resulting polysaccharides are structurally characterized and the respective antioxidant and antimicrobial activities are determined. Porphyran treated with the N-(2-hydroxy-3,5-di-tert-butyl-benzyl)-L-tyrosine derivative, POR-L2, presents a noticeable superior radical scavenging and antioxidant activity compared to native porphyran, POR. Furthermore, it exhibited some antimicrobial activity against S. aureus. The surface morphology of films prepared by casting with native and modified porphyrans is studied by SEM/EDS. Both POR and POR-L2 present potential applicability in the production of films and washable coatings for food packaging with improved protecting characteristics.

The effect of different factors on electrochemical obtaining of alloys Re-Te-Cu

Based on the study of volt-ampere dependencies during electroreduction of rhenium (VII), tellurium (IV) and copper (II) ions from hydrochloric acid electrolyte on Pt electrode, the conditions of deposition of nano-coatings of ternary Re-Te-Cu alloy were determined. The influence of various factors such as amounts of individual components and total con­cen­tra­tions of components in the electrolyte solution, temperature, concentration of hydro­chloric acid, etc., on the composition and quality of coatings was studied. It was establ­i­shed that with the increase of rhenium concentration in the electrolyte, as well as increase of temperature, the rhenium content in deposits increased. The morphology of films depo­sited on platinum substrate was studied using the scanning electron microscopy. Based on the experimental data, the following electrolyte composition (mol/l) is recommended for obtaining the semiconductor Re-Te-Cu alloy containing 40-50 wt.% Re: (6.9·10-4-6.9·10-3) KReO4 + (9·10-4-1.8·10-2) TeO2 + (6·10-4-1.2·10-2) CuCl2·2H2O +2 HCl, T = 75 °C.

ELECTROCHEMICAL OBTAINING AND MORPHOLOGY OF ALLOYS’ NANOCOVERINGS IN SYSTEM Re-Сu-Se

Electrochemical obtaining of nano-coatings in the system Re-Cu-Se on platinum electrode during voltammetric cycling was studied. The research was carried out using sulphate solution containing selenium dioxide, potassium perrenate and copper chloride. For obtaining nano coatings in the Re-Cu-Se system, we used an electrolyte of the following composition (mol/l): 6.9 ∙ 10-4 – 6.9 ∙ 10-3 KReO4 + 9 ∙ 10-4 – 1.8 ∙ 10-2 SeO2 + 6 ∙ 10-4 – 1.2 ∙ 10-2 CuCl2 ∙ 2H2O +2 H2SO4, t = 80 ºC; V = 0.005VS-1; pH = 0.1, electrode - Pt. Based on the studying of the volt-ampere dependences during the joint electroreduction of rhenium (VII), selenium (IV) and copper (II) ions from sulfate electrolytes on a PT electrode, the conditions for the deposition of alloys nanocoatings in the Re-Cu-Se system were established. To study the morphology of films on platinum and copper substrates, the electrode surface was studied using a JEOL JSM7600F scanning electron microscope at various magnifications, and was accordingly subjected to elemental analysis using an Oxford X-MAX 50 detector. The sample has been scanned in the mode of secondary electrons at an accelerating voltage ~ 15 keV. It has been found that agglomerates are observed on the electrode surface, mainly consisting of sphere-shaped particles with an average size of ~ 20-25 nm. The spectrum of characteristic X-ray radiation indicates the presence of these components of the system, allows quantitative analysis of samples. Based on the presented distribution diagram by weight percent, the content of system components is represented by the following ratio: Re-12%, Cu-5%, Se-10%. The presence of characteristic peaks of carbon and oxygen in the spectrum is explained by residual phenomena during obtaining.

Development of leftover rice/gelatin interpenetrating polymer network films for food packaging

Waste biomass can be used as a raw material for food packaging. Different concentrations of gelatin (GEL) were introduced into the leftover rice (LR) system to form an interpenetrating polymer network (IPN) for improving the properties of the films. The structure and morphology of films were evaluated by Fourier transform infrared, scanning electron microscopy, and atomic force microscopy, which showed good compatibility between LR and GEL. The moisture content and oil absorption rate of IPN films were down by 105% and 182%, respectively, which showed better water and oil resistance than the LR film. In addition, increasing GEL concentration led to enhancement in the tensile strength of films from 2.42 to 11.40 MPa. The water contact angle value of the IPN films (117.53°) increased by 147% than the LR film (47.56°). The low haze of IPN films was obtained with the increment of the mutual entanglement of LR and GEL. The 30–50% GEL addition improved the water vapor barrier and thermal stability properties of the IPN films. This study highlights that LR as waste biomass can have a practical application in food packaging.

Enhancement Efficiency of Active Layer P3HT:POT:DBSA/PCBM Photoactive Solar Cell Device

In this work we have investigated thin film blend produced from regioregular poly(3-hexylthiophene) (rr-P3HT), Poly(o-toluidine) doped with dodecylbenzene sulphonic (POT:DBSA) and [6,6]-phenyl-C61 butyric acid methylester (PCBM) materials by spin coating method for application as active layer in photoactive solar cell (PSCs). A thin film uniform rr-P3HT:PCBM and rr-P3HT:POT:DBSA:PCBM were successfully deposited on the poly (3,4 ethylenedioxythiophene): poly (styrenesulfonate) (PEDOT:PSS) buffer layer substrate. The absorption spectra of the films were studied by using UV–vis spectrophotometer and Raman spectroscopy. the morphology of films is evaluated by X-ray diffraction (XRD) and atomic force microscopy (AFM) patterns. We have seen that, the efficiency enhancement for the device with a rr-P3HT:POT:DBSA:PCBM film is more significant than for the device with rr-P3HT:PCBM.

The Effect of Annealing and Nickel Concentrations on the Structural Properties of the Nickel-Doped Cupric Oxide Nanoparticles

The effects of both annealing temperatures and nickel (Ni) concentrations of nickel doped cupric oxide (Ni– CuO) thin films were investigated in this work. Different doping concentrations of Ni (0, 20, 30, 50, 70, and 80%) were introduced to the CuO using the radio frequency magnetron sputtering technique. The resulting 60 nm films were then annealed for one hour to 200 °C and 400 °C under ambient conditions. The X-ray diffraction images revealed that annealing of Ni–CuO films changed their nature from an amorphous structure to a polycrystalline structure with a monoclinic phase. Increasing the Ni concentration increased the size of the crystallite while decreasing the dislocation density. Examining the surface morphology of films using field emission scanning electron microscopy and atomic force microscopy showed a presence of nanoparticles grains covering the whole surfaces, with perimeters ranging between 135 nm and 215 nm. Increasing the annealing temperatures reduced surface roughness, while an increase of Ni concentration increased surface roughness.