Processing conditions for the production of polystyrene microcapsules containing demineralized water

Abstract

Microencapsulation has been important for engineering, biology, medicine, and several other fields of science. Microencapsulation is an effective way to protect the encapsulated material (e.g. an aqueous solution or pharmaceutical drug) and control its release to the external environment. Microcapsules are also used for producing anticorrosion systems and, in this case, studies about polymeric microcapsules containing acid solutions are relevant. In this paper, polystyrene microcapsules containing demineralized water were produced. The influence of the core-to-shell ratio, evaporation temperature, and the presence of sodium chloride and a surfactant on the yield of the microencapsulation process was evaluated. Microcapsules were characterized by scanning electron microscopy (SEM), and thermogravimetry that revealed the morphology and thermal behavior of microcapsules in response to changing core-to-shell ratios. SEM images showed mononuclear microcapsules with smooth surfaces. The results indicated that a core-to-shell ratio of 2:1 showed the best encapsulation performance under the conditions of this study. An increase in yield of about 38% was achieved by reducing the evaporation temperature. In addition, the yields obtained in this research are considerably higher than those found in literature.