Produção de filmes de borracha natural sobre superfícies microestruturadas

Abstract

In this work, silica particles (SiO2) with different charges were synthesized, aiming the formation of different microstructures on model surfaces. The microstructures were, then, coated with natural rubber (NR) films originated from two sources: NR particles suspension in water and NR solution in chloroform. Through SiO2 particles synthesis following the sol-gel method e further functionalization (i.e. silanization), it was able to obtain particles with a size of approximately 850 nm and Zeta potential of -65 mV for the synthesized particles and 910 nm and +27 mV for the functionalized particles. The deposition and cure (at 500 oC) of the particles on the surface created particle “islands” on top of the substrate (i.e. microstrucutres of particle agglomerates). The larger area of the “islands”, as well as its’ higher height, showed a decreased surface wettability, as verified by contact angle measurements. The microstructures’ further coating with natural rubber films yielded less wettability of the surfaces. When it comes to the film produced from the chloroform solution, the final roughness resulting from the NR film self-organization produces a more hydrophobic surface, when compared to the film originated from the NR aqueous suspension. Natural rubber films were studied by using scanning electron microscopy and laser scanning confocal microscopy. The NR films autofluorescence exempted the use of fluorophores for the last technique.With the images obtained from the microscopy techniques, it was found that the morphological homogeneity from the NR films, as well as the coverage (surface coverage total area) is influenced by the type of microstructure on the surface. Higher concentration of SiO2 particles’ “islands” yield a more homogenous (with less defects) NR films. Finally, the surface covered area increases with a growing number or SiO2 utilized on the microstructuration. A surface in which less bacteria could adhere is a potential application for these films.