silica

The adsorption of glycine on amorphous silica surface has been studied to demonstrate the catalytic activity of silica surfaces towards the formation of peptide bonds on prebiotic earth. Silica nanoparticles were synthesized using a microwave assisted method and the nanoparticles were characterized using SEM. Glycine was adsorbed from aqueous solution on the nanoparticles and the adsorption behavior was characterized using FTIR and TGA analyses. At a glycine concentration of 0.5M and at pH=7, favorable adsorption was observed which obeyed the Langmuir isotherm model.

This work deals with synthesis, characterization and evaluation of post-metallocene complexes based on silica-supported bis(imino)pyridine iron, containing amino groups in ethylene polymerizations. The reaction of these complexes and methylaluminoxane generated active species in heterogeneous ethylene polymerization. The absence of substituents at the ortho-position of the phenyl rings near the metal site was not compensated by the steric hindrance of the silica surface, negatively affecting the catalytic activity and the molar mass of the produced polymer.

Melamine sulfate (Si-MelaSO4H) was prepared by treated melamine, which was immobilized onto silica (Si-Mela) with 0.05 M sulfuric acid at room temperature. The TGA confirmed that the thermal stability could reach 473 K. The XRD pattern showed that in some patterns there were sharp peaks and in other pattern a broad band was shown, which indicated that the surface is a mix of crystalline and non-crystalline nature. The Si-MelaSO4H was used successfully in the preparation of Schiff bases and its derivatives.

Cross-linked nanocomposite hydrogels based on poly(acryl amide) and mineral nanoparticles (NP) of hydroxyapatite (HAP), ZnO, TiO2 modified by reactive polymers were synthesized via the technique of polymerization filling. It was shown that physico-mechanical properties of obtained nanocomposites are determined to a great extend by the nature of the modifier of mineral NP.

The physico-chemical regularities of polypropylene microfibers obtained via processing polypropylene/copolyamide (PP/CPA) mixture melts filled with nanosilicas have been investigated. It has been shown that the chemical nature of silica functional groups affects the viscosity of PP/CPA melts. In spite of the solid state of additives the filling effect does not occur or reveals weakly. Silicas do not prevent the polypropylene fiber-forming in a copolyamide matrix but improve it. This is explained by the stabilizing action of silica additives on PP liquid streams.