doctoralThesis
Desenvolvimento de um sistema de polimerização por atomização para a formação de partículas em escala micro e sub-micro
Fecha
2016-03-18Registro en:
FERNANDES, Lenita da Silva Lúcio. Desenvolvimento de um sistema de polimerização por atomização para a formação de partículas em escala micro e sub-micro. 2016. 167f. Tese (Doutorado em Engenharia Química) - Centro de Tecnologia, Universidade Federal do Rio Grande do Norte, Natal, 2016.
Autor
Fernandes, Lenita da Silva Lúcio
Resumen
Nanoparticles are of great scientific interest due to a wide variety of potential
applications in biomedicine, optical and electronic fields. Many studies have been carried out
in order to produce polymeric particles in nano scale. The main reason for this is the higher
ratio of surface area per volume, which results in specific characteristics. Such considerations
have driven researchers to develop techniques to obtain polymeric nanoparticles with
properties that allow application in different areas. In the present work is proposed a
polymerization process by atomization applied to miniemulsion and suspension systems for
formation of submicron particles of poly(methyl methacrylate) (PMMA) and polystyrene
(PS), in the form of homopolymer and copolymer. In this technique, a simple atomizer device
is used as an alternative method to generate the monomer droplets before the dispersion in
reaction medium. Reactions using the proposed technique were carried out and the particles of
PMMA and PS obtained by suspension or miniemulsion polymerizations were analyzed by
dynamic light scattering (DLS), scanning electron microscopy (SEM) and transmission
electron microscopy (TEM). It was observed through DLS analysis that polymeric particles
were obtained with average size between 40 and 1400 nm. Concerning the SEM and TEM
analysis, it was possible to observe that the particles generally reached sizes below 200 nm
and with well-defined and spherical morphological characteristics. Such results were obtained
even in the polymerizations using suspension formulations, which is not common of getting
with conventional techniques. On the other hand, the proposed technique in this study has
demonstrated difficulty in reaching high solid contents, being the maximum value obtained of
130 g/L. Such limitation is associated with the drag of the monomer droplets during
atomization, being this effect more particularly pronounced when the monomer is more
volatile. For this reason, different configurations of the polymerization system were tested for
the purpose of improvement of results. Besides to demonstrate that is able to obtain polymeric
nanoparticles, the technique proposed in this work looks promising in obtaining carrier
particles, being, therefore, an interesting alternative by the facility of adaptation to large scale,
differently of the conventional methods of polymeric nanoparticles production.