Fragrances can be powerful. They can sooth or revitalize, evoke the forest or sea, and remind us of the past. To capture them, manufacturers infuse scents into products from toilet bowl cleaners to luxury perfumes. But once released from a bottle, fragrances evaporate quickly. Now researchers report in the journal ACS Applied Materials & Interfaces a new way to encapsulate fragrance molecules to make a product's scent last.
The challenge with creating long-lasting fragrances is that aroma molecules tend to be small and volatile. That means they can sneak through barriers easily and disperse quickly. Some methods have been developed to prevent fragrance molecules from hastily escaping from a spritz of perfume or a dollop of lotion. For example, one process slows down the molecules by packaging them in microcapsules. But the technique is inefficient and doesn't control for shell size, thickness or structure, which makes it harder to work with. David A. Weitz and colleagues wanted to figure out a new strategy using microfluidic and bulk emulsification to encapsulate fragrances.
First, to get a homogeneous mixture of water and α-pinene molecules -- found in oils from pine trees and rosemary -- the researchers emulsified them (think blending together two ingredients like oil and vinegar that normally separate). Pumping the emulsion into tiny glass microfluidic tubes created uniform microcapsules. Testing showed that the capsules successfully slowed the release of α-pinene. In addition to its use in the fragrance industry, the researchers say the technique could have applications in drug delivery or other areas.
The authors acknowledge funding from Procter & Gamble Co., the National Science Foundation, the Harvard Materials Research Science and Engineering Center, and the National Research Foundation of Korea.
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