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Международная молодежная научная школа «Школа научно-технического творчества и концептуального проектирования». Коллектив авторов
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isbn 978-5-7882-1300-2
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The effect of transition metal oxides deposited on the polymer matrix in the sodium sulfide oxidation is given in Figure 1.
Fig. 1 The effect of transition metal oxides deposited on the polymer matrix in the sodium sulfide oxidation.
It is apparent from the Figure that copper and manganese oxides show maximum activity in the sodium sulfide oxidation, in this case intial rate of reaction is, respectively, about 1,4 and 1,35 times higher than intial rate of no catalyst. Oxides of NiO, Co3O4, Cr2O3, TiO2 – show insignificant activity, a part from the tested oxides: V2O5, Fe2O3 – don't influence rate of reaction, and catalysts based on the MoO3 oxide- even inhibit sodium sulfide oxidation.
Fig. 2 The effect of mixed compositions by different concentration of copper and manganese oxides in the sodium sulfide oxidation.
Catalytic activity of mixed compositions, which were synthesized by different concentration of copper and manganese oxides shows that CuO5/MnO2-15 possesses highest activity for sodium sulfide oxidation (Fig. 2).
Influence of the heterogeneous catalyst amount on the rate of reaction shows that increasing catalyst amount to 5,0 g leads to increase the rate of sodium sulfide oxidation. The further increases in catalyst amount don't influence rate of reaction (Fig. 3).
Fig. 3 Influence of the heterogeneous catalyst amount on the rate of sodium sulfide oxidation
Fig. 4 Influence of temperature on the rate of sodium sulfide oxidation
Influence of temperature on the rate of reaction shows that the maximum rate of sodium sulfide oxidation is observed at temperature 600С, above and below 60 0С rate of reaction is decreased (Fig. 4).
Kinetic methods show that all reactions are first order with respect to the [O2] and zero – to the concentration of sulfur compounds (Fig. 5).
Fig. 5 Logarithmic dependence of rate of sodium sulfide oxidation on concentration О2
IMIDAZOLIUM BASED POLYMERIC IONIC LIQUIDS AS POLYMER ELECTROLYTE MEMBRANES
Ionic liquids are defined as molecules containing a permanent charge and a melting point below 100 oC [1]. Although it is not a requirement, in general, the more common ionic liquids possess an organic cation and an inorganic anion. Ionic liquids are receiving an upsurge of interest for their unique physicochemical properties such as high thermal stability, negligible vapor pressure, relatively high ionic conductivity, and good electrochemical stability.
Ionic liquids have also been quite popular recently due to their potential application as green chemical reaction solvents and water treatment agents. The permanent charge provides many useful applications, such as electroactive devices and actuators. They serve as charge exchange films in electroactive devices or ionic liquids and can be used to improve existing films upon swelling, which leads to enhance the conductivity of the actuator.
Solid electrolytes play an important role in the development of new energy sources, like solid state batteries, fuel cells, photoelectrochemical solar cells, sensors and electrochromic displays [2,3]. Obtaining high ionic conductivity over a wide temperature range becomes crucial for the realization of these technological applications. Traditional ion-conducting polymers such as poly(ethylene oxide) – based polymer electrolytes, are solid solutions of salts in polymers [4-7]. Ionic motion in these polymer electrolytes is coupled with the local segmental motion of the polymer. In this type of electrolytes an increase of carrier-ion density and mobility are difficult to achieve because both, depend on the interaction of polymer segments with the ions. Various research groups [8–11] have been involved actively to synthesize polymer electrolytes with high conductivities, but up to now the desired conductivities, particularly at high temperatures, have not been attained. Hydrated perfluorosulfonic polymer shows superior performance in fuel cells operating at moderate temperature (<90 ◦C), however, the properties of such polymer membranes are insufficient at higher temperatures. This puts new demands on the development of alternative polymeric proton exchange membranes [12]. Based on this concept, the use of ionic liquids appears to be promising with respect to high ion conductivity in polymers. Due to an ionic liquid’s ability to facilitate electron or ion motion, they are now enabling electroactive devices. Commercially available conductive membranes are swollen with ionic liquids to enhance their conductivity; alternatively, conductive membranes are synthesized from novel ionic liquid monomers, also termed polymerizable ionic liquids. The imidazole ring has gained much attention for its ability to tune the properties of the resulting ionic liquid. The imidazole ring is a very versatile scaffold for ionic liquids. The ring is easily ionized upon quaternization of the tertiary nitrogen atom, resulting in a permanent positive charge. A unique combination of various alkyl substituents and counteranions enables tuning of the physical properties of the liquid such as the melting point, the boiling point, and the viscosity to meet the demands of the application. The structure is uniquely tunable because of the inherent amphoteric behavior, i.e. the imidazole ring both accepts and donates protons. Finally, the imidazolium cation is associated with a mobile counteranion, which can be exchanged to further tune solubility and conductivity [13].
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2. F.M. Gray, Solid Polymer Electrolytes, VCH, New York, 1992.
3. A.M. Anderson, C.G. Granquist, J.R. Stevens, Appl. Opt. 28 (1989) 3295.
4. M.B. Armand, Ann. Rev. Mater. Sci. 16 (1986) 245.
5. C.A.Vincent, Prog. Solid State Chem. 17 (1987) 145.
6. M.Watanabe, N. Ogata, Br. Polym. J. 20 (1988) 181.
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8. D.E. Fenton, J.M. Parker, P.V. Wright, Polymer 14 (1973) 589.
9. M.B. Armand, J.M. Chabagno, M. Duclot, 2nd International Conference on Solid Electrolytes, St. Andrews, 1978, p. 651.
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[11] G.B. Appetecchi, F. Croce, B. Scrosati, J. Power Source 66 (1997) 77.
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13. Marcilla, R., Blazquez, J. A., Rodriguez, J., Pomposo, J. A., Mecerreyes, D. Journal of Polymer Science Part A: Polymer Chemistry 2004, 42 (1), 208–212.
BIODEGRADABLE POLYMERS FOR TISSUE ENGINEERING APPLICATIONS
Tissue engineering is an interdisciplinary field that blends classical engineering and the life sciences to repair or replace damaged tissues. The most common strategy to achieve this goal is to culture of patient’s own cell onto a three dimensional support matrix, so called scaffold, and then implant this construct to the patient. The function of a degradable scaffold is to act as a temporary support matrix for transplanted or host cells so as to restore, maintain, or improve tissue. The design of a polymeric scaffold plays a significant role in proper cell growth. Therefore, several important properties must be considered: fabrication, structure, biocompatibility, biodegradability, and mechanical strength.
Scaffolds may be created from various types of materials, including polymers. There are two sources of polymers used in tissue engineering: synthetic and natural. The main biodegradable synthetic