Nanocomposites and nanomaterials

Preparation of polymer-mineral nanocomposites based on vinyl monomers and dispersed inorganic oxides
Dutka V.S., Kovalskyi Ya.P., Aksimentyeva O.I., Oshchapovska N.V.
Department of Physical and Colloid Chemistry,Ivan Franko National University of Lviv, Kyryla&Mefodia str. 6, 79005 Lviv, Ukraine
E-mail: vdutka @ukr.net

Polymer-mineral nanocomposites have unique features that combine the useful properties of both components. The formation of polymer in systems filled with dispersed minerals is significantly influenced by the nature and dispersion of inorganic oxides, the type of radical initiator, and the monomer that is polymerized under these conditions.
In our work polymerization of styrene, methyl acrylate, methyl methacrylate and butyl methacrylate has been investigated in the presence of nanoparticles of aerosil, TiO2, PbO, V2O5, Fe2O3, Cr2O3. As initiators of radical polymerization, benzoyl peroxide (PB), oligomeric peroxide of sebacic acid (OSA), tributyl hydroperoxide (HPTB), and other were used. The surface of the investigated mineral disperse oxides adsorbs the components of the polymerization medium. Adsorption of peroxide initiators on aerosil, MgO, V2O5, Fe2O3, Cr2O3 from styrene solution was studied. The process of adsorption of the studied peroxides on the listed mineral oxides is well described by the known equation of Langmuir's monomolecular adsorption. The basic parameters of the adsorption process are determined. In the case of adsorption from solutions of compounds such as methyl methacrylate or butyl acrylate, competitive adsorption of peroxides and oxygen-containing monomers is observed. Investigation of the thermal decomposition of peroxide compounds in the presence of disperse oxides showed that the destruction of initiators runs in the solution of the monomer and on the surface of the mineral.
The peroxides adsorbed on the surface of the aerosil and Cr2O3 decompose in a heterogeneous mechanism during which no radicals can initiate polymerization. The reaction of peroxide initiators with a surface V2O5, Fe2O3 PbO has an oxidation-reduction nature. In the course of this interaction, free radicals are formed which can cause polymerization. The polymerization process in the presence of the studied disperse oxides leads to the formation of a polymer of mineral composites. Part of the polymer molecules that have been formed in the studied systems are grafted to the surface of mineral fillers. Polymerization in such systems takes place in a solution and with the participation of the surface of mineral oxide. The molecular masses of polymers, which are formed in the studied systems, are determined. The surface of disperse oxide takes an active part in the process of formation of polymer-mineral composite.