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OBjECTIVES

The overall objective of the project seeks to achieve results capable to lead to the development of knowledge in the field of polymer nanocomposites with possible industrial applications. The project would increase the institute research capacity, national and international visibility and exploitation of the results by providing supplementary funding.

Scientific objective of the research program is the development of stable nanodisperse systems respectively nanocomposite materials starting from monomers with different polarities and new nanomaterials (superhidrofobic layered silicates). Two major objectives with the mentioned specific activities will be followed:

   1.  Obtaining and physico-chemical characterization of superhydrofobic silicates. It is estimated the obtaining of superhydrofobic silicate by edge covalent bonding through sol-gel processes of different organophilic silicates (Cloisite 30B, 20A, 15A, Cl 20A) with diverse monofunctional alkoxysilane of different carbohydrate chain lengths (trimethyl ethoxysilane (Me3ES), vinyl dimethylethoxysilane (VMe2ES), phenyl dimethylethoxysilane (PhMe2ES), octyl dimetilmethoxysilane (C8Me2MS), octadecyl dimethyl methoxysilane (C18Me2MS). Our goal is to disperse the silicate as well, to assure a better compatibility with the monomer / polymer, therefore, it is absolutely necessary to modify the silicates surface, these issues could generate a material with special properties beyond the traditional.

For proving the functionalization of the silicates, following analyses will be performed: - ATG thermal analysis (calculating the degree of substitution), DSC, X-ray fluorescence (elemental analysis of the products), FTIR Spectroscopy (observation the structure of the silicates), and determination of Zeta potential, particle size. In order to demonstrate the interaction, intercalation or exfoliation of layered silicates in the process of synthesis, XRD and electron microscopy studies, will be realized. The structure - properties correlation depending on the nature of silicates/functionalization agents by studying the behavior of silicate in monomers of different polarities as well as the study of the interactions at the interface hydrophobic silicate - reaction medium, will be followed.

   2.  Obtaining and physico-chemical characterization of aqueous dispersions/polymer-superhydrophobic silicate nanocomposite materials. This study will continue the research started on the PhD thesis regarding the obtaining of polystyrene-modified NaMMT nanostructured materials. It is estimate to obtain advanced materials by emulsion polymerization in aqueous medium (with/without surfactant, microemulsion) of monomers with different polarities (styrene sulphonate, cuaternary styrene, styrene, butyl acrylate, methyl methacrylate) in the presence/absence of superhydrophobic layered silicates (organophilic layered silicate modified by egde covalent bonding with diverse functionalization agents, such as: trimethyl ethoxysilane - Me3ES, vinyl dimethylethoxysilane - VMe2ES, phenyl dimethylethoxysilane - PhMe2ES, octyl dimetilmethoxysilane - C8Me2MS, octadecyl dimethyl methoxysilane - C18Me2MS).

The study of the influences of nature and concentrations of reactants on the physicochemical properties of the obtained composites and the effect of nature of layered silicates and/or alkoxysilanes on their compatibility in the polymer will constitute another stage of our research. The latexes obtained by polymerization in disperse medium in the presence of hydrofobic silicates, shall be subject for Zeta potential determinations, particle size, and electron microscopy. To prove the silicates interaction with the polymer matrix, polymer-superhydrofobic silicate nanocomposite materials obtained after washing, drying, ultracentrifugation of the samples will be subjected to FTIR analysis, ATG, DSC, DMA, X-ray fluorescence, DMA. XRD an electronic microscopy analyses will be realized to demonstrate interaction, intercalation or exfoliation of the hydrophobic silicates in different polymeric matrices.

As for the working methodology, synthesis of the superhydrofobic silicates will be done through sol-gel processes of monofunctional alkoxysilane, carried out at the ends of silicate. The obtaining of polymer- superhydrofobic silicate nanostructured materials will be made by methodologies in which the project director and also the team have experience, as evidenced by a significant number of published papers. It will be used the method of polymerization in aqueous medium (emulsion with/without surfactant, microemulsion) with the direct dispersion of silicate in the monomer. Also, will be developed new methodologies that will highlight effective use of these new nano-superhydrofobic silicate materials. Physicochemical characterization, structure-property correlations will be adjusted taking into account the structure of partners.

All the results obtained during the proposed study will be brought to researcher's attention by communications, articles, and presentations at conferences.