Síntese e caracterização de partículas Janus (Si-Au)

Abstract

Janus are colloidal particles with more than a single type of chemistry or surface composition, and can be of diferent sizes and shapes. Their anisotropic structure (diferent characteristics in diferent directions) allows them to present multifunctional properties in the same particle, such as optical, chemical and magnetic properties, leading to several application opportunities, such as in industry and biomedicine. The purpose of this work was to develop a literature review on the main methodologies used to synthesize Janus particles, and also their main assembly properties in nanometric structures. In addition, it aimed to develop a methodology for the synthesis of Janus silica and gold (Si-Au) particles, using a Pickering emulsion with parafin and silica particles, followed by a process of functionalization of these particles exposed surfaces. Both silica and gold particles were obtained by chemical reaction. The silica particles were characterized in the equipment Scanning Mobility Particle Sizer (SMPS) and was obtained an average aerodynamic diameter of 25.85 +/- 1.57 nm, while the gold particles were characterized by spectrophotometry and was obtained an average diameter of 16.61 +/- 0.33 nm. The parafin solution with silica particles was observed under an optical microscope and it was possible to visualize micrometric droplets of the Pickering solution and, subsequently, the solution without the parafin and with the addition of gold after the functionalization of the silica particles was observed. The characterizations were not performed by SEM due to the current pandemic situation, however, such particles will be characterized in the future, and the results showed the attainment of Janus Si-Au particles. Although the application of Janus particles is not within the scope of this work, the methodology presented allows synthesizing such particles in large laboratory quantities, in the gram scale, and can be easily replicated and could also come to be scaled-up at an industrial level. Janus Si-Au particles have several application potentials, such as surfactants in oil-water emulsions, and many others in biomedicine and agriculture.