Synthesis and studies of poly(ethylene glycol dimethacrylate) microcapsule

Mixture of dementholized peppermint oil (DPO) and caprylic/capric triglyceride (GTCC) was encapsulated by poly(ethylene glycol dimethacrylate) (PEGDMA) shell polymerized with monomer ethylene glycol dimethacrylate (EGDMA). PEGDMA microcapsules were prepared through a novel interfacial free radical polymerization of monomer EGDMA in oil phase triggered at the oil-in-water (o/w) interface by initiator ammonium persulfate (APS) in aqueous phase. In addition, interfacial free radical polymerization mechanism for forming the PEGDMA shell was proposed. Scanning electron microscope (SEM) images showed that the microcapsules possessed a spherical morphology as the ratio of GTCC/DPO was 1:1. Optimal condition for a high encapsulation efficiency of 91.50 wt% was found with 3 wt% emulsifier gum arabic at a homogenization rate of 8000 rpm for 4 min. The thermal stability of the microcapsule was investigated by thermogravimetric analysis (TGA), which indicated that the microcapsules had a much better thermal stability than pure core materials. The controlled release mechanism of the encapsulated DPO diffusing through the PEGDMA shell conformed to the Weibull equation.