Microencapsulation mechanism and size control of fragrance microcapsules with melamine resin shell

• The microcapsules containing essence oil were synthesized successfully.
• The mechanism of the microencapsulation was proposed.
• The particle size of microcapsules is controllable based on the proposed mechanism.

Fragrance microcapsules, with a methanol-modified melamine-formaldehyde (MMF) resin shell, were fabricated with an in situ polymerization method in the presence of styrene-maleic anhydride copolymer (SMA). The FT-IR results showed that the essence oil was encapsulated by MMF resin, and TG-DTG tests indicated that its thermal stability was improved significantly by the microencapsulation. The fabrication process was observed by reflection and transmission optical microscope, and the encapsulation mechanism was studied according to the observation results. It was found that the adsorption of MMF resin to SMA and the polycondensation reaction kinetics played key roles in the microencapsulation process. Additionally, the process of microencapsulation contains two re-formations, which were caused by the pH effect in the hydrolysis of SMA and the redispersion of droplets in curing process. According to the proposed encapsulation mechanism, a series of microcapsules with different size and distribution were prepared by the adjustment of reaction parameters.

Figure optionsDownload as PowerPoint slide