Poly(methyl methacrylate)-microencapsulated clove oil slow release formulation

Abstract

Essential oils are known to have many uses such as for medicinal and pesticidal components but their high volatility limits their applications. Encapsulation or controlled release device is desirable for effective applications of essential oils. This study investigates the encapsulation of clove essential oil in porous polymeric particles to affect its slow release. Poly (methyl methacrylate) (PMMA) was prepared using free radical polymerization of methyl methacrylate. The material was characterized by NMR spectroscopy. The results have shown that the polymerization process was complete as evidenced by the absence of peaks for double bond at 6.0 and 5.5 ppm compared to those of the monomer. It was also confirmed by attenuated total reflection (ATR) infrared spectroscopy that indicated the presence of functional groups of the polymer. Meanwhile, clove oil was extracted from clove buds by hydrodistillation.  Encapsulation was carried out by solvent evaporation method using oil in water (O/W) emulsion system. PMMA with encapsulated clove oil were formed using different PMMA: clove oil ratios. It was found that ratio of 1:1 resulted in the formation of beads but ratios of 2:1 and 3:1 did not form beads but clots instead. The presence of eugenol, an active component in clove oil, in the PMMA encapsulation was confirmed by gas chromatography with flame ionization detection based on comparison with the standard. Experiments on the slow release of PMMA-encapsulated clove oil were carried out and the weight loss was monitored at 10, 20, 30, 40, 50, 60, 120, 180 and 240 min. Similar experiments were performed using silica-clove, montmorillonite-clove and clove alone for comparison. It was found that PMMA-clove encapsulation showed the best performance followed by silica-clove, montmorillonite-clove and clove alone. Thus, PMMA encapsulation is highly potential as an effective formulation in controlled release of volatile compounds