Desenvolvimento e caracterização de nanocompósitos produzidos a partir de miniemulsão acrílica aquosa contendo nanopartículas de prata

Abstract

Lately, the polymer latices have gained increasing importance having the great advantage of using water as a solvent, that reduces the emission of volatile organic compounds a big environmental concern. In the industry, the polymeric latices are obtained usually through an emulsion polymerization. They can also be obtained by the polymerization in miniemulsion, a technique that has other advantages such as the incorporation of inorganic solids and the obtaining of nanocapsules. In this study, an aqueous solution of silver nanoparticles was incorporated as the continuous phase (aqueous) to a disperse phase (oil). This solution contains mainly the monomers styrene and butyl acrylate, two compounds that are extensively used in the paint and adhesive industries. To this mixture was added the hydrophobic agent hexadecane and the final solution was submitted to thermodynamic stabilization by ultrasound. The latices obtained with 25% and 45% of solids, produced by the process of free radicals polymerization in aqueous miniemulsion, were characterized in terms of particle size. The nanocomposites obtained from the latices were studied by Infrared Spectroscopy (FTIR) and the absence of absorption bands related to the double bond between carbons showed the efficiency of the polymerization. Spectra of X-ray fluorescence (XRF) showed energy peaks that are related to silver, indicating its incorporation in the polymer matrices. The thermal properties were investigated by the use of the techniques: Differential Scanning Calorimetry (DSC) and Thermogravimetry (TGA), that showed a slight increase in the Tg and on the set temperature of mass loss in samples with silver nanoparticles. The mechanical behavior of the produced films was evaluated by a traction test. Adhesion tests showed excellence in this feature for the films deposited on polar polymeric substrate, demonstrating their potential for use in paints or polymercoatings.