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Mechanical, thermal and surface properties of polyacrylamide/dextran semi-interpenetrating network hydrogels tuned by the synthesis temperature

100%

Dinu M., Cazacu M., Drăgan E.

Open Chemistry

2013

vol. 11

issue 2

248-258

The mechanical, rheological, thermal, and surface behaviors of three polyacrylamide/dextran (PAAm/Dx) semi-interpenetrating polymer network (semi-IPN) hydrogels, prepared at 22°C, 5°C and −18°C, were investigated. The results were compared with those obtained on cross-linked PAAm without Dx synthesized under the same conditions. Hydrogels prepared at the lowest temperature were the most mechanically stable. The thermal stability of the semi-IPN hydrogels is slightly lower than the corresponding PAAm gels, irrespective of preparation temperature. The water vapor sorption capacity depended on the presence of Dx as well as preparation temperature, which determines the network morphology. [...]

New iron-cobalt clusters with silicon-containing dicarboxylic acids

100%

Cazacu M., Vlad A., Turta C., Lisa G.

Open Chemistry

2012

vol. 10

issue 4

1079-1086

For the first time, silicon-containing dicarboxylic acids were used to prepare two new heterotrinuclear carboxylates of the composition [Fe2IIICoIIO(Bcpdps)3(H2O)3], I, where H2Bcpdps ≡ HOOC-C6H4-Si(C6H5)2-C6H4COOH, and [Fe2IIICoIIO(Ipds)3(H2O)3], II, where H2Ipds ≡ [HOOC-C6H3(CO)2N-(CH2)3-(CH3)2Si]2O. The precursor for these two complexes was trinuclear µ3-oxo-hexaacetate triaqua diiron(III)cobalt(II) cluster, {Fe 2 CoO}, in which the acetate anions were subsequently substituted by silicon-containing dianions. The resulting products were characterized by elemental analysis, thermogravimetry, Fourier Transform Infrared (FTIR), Energy-Dispersive X-ray Fluorescence (EDXRF), and Mossbauer spectroscopies (MS). The investigation by MS revealed the presence of the iron(3+) ions in high spin state and having the close environment. Thermogravimetric analysis results indicated an improving in the thermal stability by replacing acetate anions with silicon-containing carboxyl ligands. This widens the temperature range in which such compounds can be used in practical applications. [...]

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2 Open Chemistry

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1 Drăgan E.

1 Lisa G.

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Mechanical, thermal and surface properties of polyacrylamide/dextran semi-interpenetrating network hydrogels tuned by the synthesis temperature

New iron-cobalt clusters with silicon-containing dicarboxylic acids