Vegetable oils acting as encapsulated bioactives and costabilizers in miniemulsion polymerization reactions

Abstract

Vegetable oils with different chemical structures were successfully encapsulated and applied as costabilizers in miniemulsion polymerization reactions. The results were compared to hexadecane, a well-known costabilizer used for this type of polymerization. The great advantage of using vegetable oils is that besides acting as costabilizers, they are also encapsulated, increasing the application of the nanoparticles. Results showed that kinetics tend to be slower with argan oil, due to the higher concentration of double bonds present in the oil. When coconut oil and jojoba oil were used, the kinetic rate kept nearly the same. The different types of costabilizers did not affect the average size of the particle, and were able to keep the miniemulsion stable throughout the reaction. DSC analysis showed a decrease in the glass transition temperature when the vegetable oils were used. However, after a long period of storage, the Tg of the polymers increased. STEM images showed the formation of nanoparticles for hexadecane and the vegetable oils. However, the nanocapsule morphology appeared only when coconut oil, jojoba oil and hexadecane were used, while for argan oil no phase separation could be detected in the polymer particle.

Practical applications: Miniemulsion polymerization reactions allow the production of polymeric nanoparticles in only one step with high encapsulation efficiency. To obtain a stable miniemulsion, it is necessary the addition of a costabilizer. The vegetable oils were chosen because besides acting as costabilizers the vegetable oils can increase the application of the nanoparticles since they have important characteristics and functionalities. Furthermore, the vegetable oils are biodegradable. In this work, we proposed two oils that are not composed of unsaturated fatty acids, unlike many vegetable oils commonly used in the literature.

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