Síntese e caracterização de microcápsulas à base de poli(ureia-formaldeído) com potencial aplicação em revestimentos inteligentes

Abstract

The term “self-healing” comprise material’s “auto-cure” capacity, being possible for those materials the autonomic restoration of their structural integrity after had suffered some damage. One possible field for the application of self-healing effect is paintings and coatings, what allows that surfaces which have suffered some kind of damage return total or partially to their initial appearance. One of possible techniques to get this effect is the application of active microencapsulated materials. Microencapsulation process leads the formation of micro sized particles, in which there is an active ingredient (core material) packaged in a second material (wall), what enable the isolation and maintenance of ideal characteristics of the substances that constitute the core material, besides the controlled release of core material under specific conditions. In the case of microencapsulation applied to surfaces technology, the microcapsules incorporated to the coating are broken when a superficial crack occurs, leading the release of active material which is able to recover damaged area. The objective of this work was synthesizing and characterizing poly(urea-formaldehyde) based microcapsules with potential application on smart coatings. The synthesis was accomplished by in situ polymerization mechanism; microcapsules were composed by poly(ureaformaldehyde) as wall material containing different core materials: dye, epoxy resin and colored epoxy resin. The physico-chemical characterization of synthesized materials was made through Optical Microscopy, Scanning Electronic Microscopy and Infrared Spectroscopy with Fourier Transform. Other analyses were also accomplished, as determination of particle average size, core material content and core material releasing test. Obtained results showed that the synthetic route was efficient on microcapsules formation, which had spherical shape and rough morphology. The particle’s size analysis showed that there is an inverse relation between stirring speed and microcapsules diameter. Infrared Spectroscopy analysis showed characteristic bands of poly(urea-formaldehyde) and the employed core materials, indicating that synthesis was effective on polymer formation and on the maintenance of original characteristics of core materials. The employed methodology for amount of encapsulated core material analysis was effective for dye systems, being that for the others it’s suggested performing tests with other solvents. In general, synthesized microcapsules showed potential application for smart coatings obtainment.