Influence of dopant on the specific features of formation and properties of nanocomposites of poly(3-methylthiophene) with polyvinylidene fluoride

The work is devoted to the development and study of conducting nanocomposites of poly(3-methylthiophene) (P3MT) and poly(vinylidene fluoride) (PVDF), suitable for changing properties when interaction with of the environment components, and to find factors of influence on properties of such materials. The kinetic aspects of P3MT formation in the process of 3-methylthiophene (3MT) polymerization in PVDF dispersions in the presence of dopants of different nature, in particular, chloride (Cl-), as well as surface-active dodecylbenzenesulfonate (DBS-) and perfluorooctanoate (PFO-) anions are studied. It is found that DBS- and PFO- anions inhibit 3MT oxidation and decrease P3MT yield in comparison with those of chloride anions. It is shown that P3MT is formed through two consecutive kinetically different reactions of pseudo-first order in terms of the oxidant concentration. Transmission electron microscopy revealed that as a result of such polymerization nanoparticles of doped P3MT formed a surface inhomogeneous layer on PVDF particles, thus forming nanocomposite particles with core-shell morphology. Thermal studies showed higher thermal stability of the doped P3MT phase in the nanocomposite compared to the pure polymer. It is found that thermal stability of the P3MT phase in the PVDF/P3MT-DBS nanocomposites is higher than in the PVDF/P3MT-Cl. The influence of the dopant nature and content of doped P3MT on conductivity and sensitivity of the nanocomposites to vapors of harmful volatile organic compounds (acetone and isopropanol) is characterized. The strongest responses to acetone are shown by the nanocomposite with PFO- dopant. In the DBS- dopant case medium intensity responses are found and the lowest ones are observed for Cl- dopant. It is shown that the sensitivity of nanocomposites extremely depends on the conducting polymer content.

Supramolecular complex of 1-methylcyclopropene with cucurbit[6]uril as efficient reagent for apples treatment

The study is dedicated to the development of novel techniques for the synthesis and analysis of supramolecular complex of 1-methylcyclopropene and cucurbit[6]uril, with a view of further development of new agricultural products, e.g. Oberigpro and others, for fruit and vegetable treatment. Synthetic procedures were significantly improved at all stages allowing time and feedstock saving, as well as process efficacy and ecological aspect enhancement. Robust analytical procedure for 1-methylcyclopropene assaying was developed with the use of high performance liquid chromatography and chemical derivatization of 1-methylcyclopropene. Moreover, the release of the active compound from the complex was considerably increased, and high complex stability under various conditions was shown. In general, the study performed allowed making Oberigpro one of the most effective products for practical application among the existing analogs, and paved the way for further development of new agricultural products with controlled action.

Supramolecular interactions in the mixtures of hydrophobic and hydrophilic pyrogenic silicas

In order to study the peculiarities of the interaction of hydrophobic particles with water, the binding of water in composite systems based on structurally modified mixtures of 1/1 hydrophilic (A-300) and hydrophobic (AM-1-300) silica was studied by low-temperature 1H NMR spectroscopy. It is shown that with equal amounts of hydrophobic and hydrophilic components, the dependence of the interfacial energy on the value of surface hydration has a bell-shaped appearance with a maximum at h = 3000 mg/g. The obtained dependence is explained from the point of view of restructuring of the composite system under the influence of mechanical loads and the possibility of air removal and adsorption processes in the interparticle gaps of hydrophobic and hydrophilic components, as well as the phenomenon of nanocoagulation. Increasing the concentration of the hydrophilic component does not increase the binding energy of water. Under the influence of liquid hydrophobic substances, depending on the bulk density of the composite, there may be an increase or decrease in interfacial energy. The growth is due to the restructuring of the hydrophobic and hydrophilic components (nanocoagulation), and the decrease is due to the displacement of water from the surface into pores of larger radius. For n-decane, the effect of increasing the melting temperature by several tens of degrees was registered in the interparticle gaps.

Mutual sensibilization in epoxyacrylate interpenetrating polymer networks

Using the method of IR spectroscopy, the kinetic features of the course of photoinitiated cationic and free radical polymerization in simultaneous epoxyacrylate interpenetrating polymer networks were investigated. The degree and rate of conversion of epoxy groups in the epoxy component (aliphatic diepoxide UP-650D, aliphatic-alicyclic triepoxide UP-650T, and diane epoxides ED-20 and Epicot 828), and the opening of double bonds in acrylate component (triethylene glycol dimethacrylate) were determined. The sensitizing effect of the acrylate component on the degree of conversion of epoxy groups in IPNs with aliphatic diepoxide or aliphatic-alicyclic triepoxide with an epoxy/acrylate ratio of 50/50 wt. % was revealed. For diane epoxies, the opposite regularity of conversion of epoxy groups in the composition of epoxy-acrylate IPNs is observed: in comparison with initial polymer networks, the degree of conversion of epoxy groups was significantly reduced. In the first case of low-viscosity aliphatic and cycloaliphatic epoxides such a sensitization is occurred due to the fact that the simultaneous polymerization of acrylate via a free radical mechanism promotes the decomposition of the photoinitiator and the formation of more macrocations quantity. In second case of more viscous diane epoxy resins, the spatial restriction imposed by the rapidly formed acrylate networks is predominate. That is why the conversion of epoxy groups is reduced and this effect is neutralized.

High-efficiency polymethine dyes for passive Q-switch and mode locking of neodymium lasers

New polymethine dyes (PD) based on benzene [c, d] indole were synthesized. Their spectral and nonlinear optical characteristics in liquid and polymer media have been studied. It was found that the relaxation times τ of the excited state of the new PDs are approximately the same as those of the dye 3274y, which is widely used as a passive Q-switch of neodymium lasers with a generation lengthwave of 1.06 μm. The low sensitivity of τ to changes in the chemical structure of such PDs indicates that the main contribution to the deactivation of the excited state is made by the benzene [c, d] indole heterocycle. High values ​​of the cross section in the range of 1.05-1.08 μm at low relaxation times allow the studied PD to be easily bleached in lasers at low intensities (about 10 MW/cm2). It is established that the photostability of the new PD significantly exceeds that for the dye 3274y. This is because they contain a saturated six-membered ring in the polymethine chain, which is much less reactive than the corresponding five-membered ring of dye 3274u with respect to the photoinitiator of free radicals of UV irradiation. It is shown that the efficiency of Q-switching and mode locking of new passive laser shutters is higher than their analogues based on the dye 3274y.

Catalytic pyrolysis of lignin-cellulose biomass and its model phenolic components on the nanosized oxides surface

Lignocellulose is currently considered as a potential renewable source of a wide range of valuable chemicals, including aromatics. Catalytic pyrolysis is the promising method for the conversion of biomass raw materials. The development of renewable biomass pyrolysis technologies requires fundamental research on catalytic thermal transformations of lignocellulosic raw materials. Therefore, in this work, the methods of IR spectroscopy, temperature programmed desorption mass spectrometry (TPD MS) and thermogravimetric analysis were used to investigate the catalytic thermal transformations of rapeseed meal (RM) and ferulic acid (FA) as a model phenol-containing component of such raw material on the surface of nanosized oxides CeO2, SiO2 TiO2/SiO2, Al2O3/SiO2 and CeO2/SiO2. The most effective catalyst in the conversion of biomass to ketones was a nanocomposite CeO2/SiO2 with the highest content of nanoparticles of CeO2 (24%). According to the data of FTIR spectroscopic studies, the interaction of FA with the CeO2 surface occurs with the participation of phenol and carboxyl groups. The main products of thermal decomposition of FA on the surface of CeO2 are 3-methoxy-4-vinylphenol, guaiacol, coumaric acid and hydroxybenzene. Condensed aromatics (naphthalene, alkylnaphthalenes) were registered in small quantities.

Synthesis, spectral and luminescent properties of new alkylamino-beta-ketoenol compounds and metal complexes on their basis for creation of fluorescent probes for biomolecules and optical materials

A series of chalcones and alkylamino-β-ketoenol dyes based on dehydroacetic acid were synthesized in this work. Their individuality is established and physicochemical properties are investigated. A number of phthalocyanine complexes of zirconium and hafnium with these β-ketoenol ligands have been obtained, and their spectral-luminescent properties have been studied. It is established that the obtained complexes absorbs light in a wide spectral range from 300 to 700 nm. Functionalized alkylamino-β-ketoenoles are reported as probes for fluorescent detection of protein aggregates that associated with dangerous diseases, including neurodegenerative disorders. Depending on the nature of the substituents, these dyes can increase the fluorescence intensity tenfold in the presence of fibrillar aggregates, but are practically insensitive to native proteins. The studied dyes have a green-yellow emission in the region of 495–540 nm. For the most effective compound (2E,5Z,7E)-8-(4-(dimethylamino)phenyl)-6-hydroxy-2-(2-methoxyethyl-amino)octa-2,5,7-trien-4-one the fluorescence quantum yield upon binding to insulin fibrils reaches 47.0%, while for the free dye this value is about 0.5%. Due to its sensing properties, this dye exceeds the properties of Thioflavin T, which is the standard for the determination of amyloid fibrils. Alkylamino-β-ketoenol dyes have been shown to be promising as fluorescent probes for the detection of β-pleated protein aggregates.

Acetalization of glycerine at presence of acid-modified clinoptilolite, bentonite and tripolite from the domestic deposits

In recent years, the situation with glycerol (Gl) has changed dramatically due to rapid development of biodiesel industry, in production of which Gl is formed in large quantities. Cyclic acetals of Gl are used as additives to motor fuels, as well as intermediates in the synthesis of various mono derivatives of Gl, which are widely used in food and pharmaceutical industries, cosmetics, etc. On the examples of Gl interaction with acetone (Ac), benzaldehyde (BA) and formaldehyde (FA), authors revealed the prospects of nitric acid-modified samples of natural clinoptilolite (H-СPT), bentonite (H-BNT) and trepel (H-TRP) from Sokirnytsky, Dashukivsky and Konoplyansky deposits of Ukraine (respectively) as catalysts for Gl transformation into cyclic acetals. Factors that determine the optimal conditions for acid modification of raw material, providing maximum conversion of Gl and catalytic activity of obtained samples, have been identified. A characteristic feature of studied processes is need to change the reaction conditions when changing the carbonyl compound-partner of Gl. It was found that number of catalyst samples obtained on H-BNT basis, their activity is superior (or comparable) with cation exchange resin KU-2.