Eco-Friendly Silica Microcapsules with Improved Fragrance Retention

Microcapsules are employed extensively in various applications; however, most are composed of synthetic plastics. Thus, substitution of their component materials is essential to prevent environmental problems associated with primary microplastics. Herein, we report the synthesis of eco-friendly silica core–shell microcapsules for fragrance retention. The silica shell was prepared via oil/water emulsion template synthesis using tetraethyl orthosilicate (TEOS), which was added to the immature silica microcapsules prior to complete formation of primary silica shells to promote seeded growth for further reaction of silica. The thickness of the silica shell increased from 42.29 to 70.03 nm, while the Brunauer–Emmett–Teller surface area and internal pore area decreased from 155.16 and 30.08 m2/g to 92.28 and 5.36 m2/g, respectively. The silica microcapsules with lower surface areas retained fragrance for more than 80 days, even in a harsh environment of 15% sodium dodecyl sulfate at 60 °C, whereas the fragrance compound in those without additional TEOS treatment was completely released within seven days. Practical qualitative evaluation of fragrance was also performed for application in fragrance delivery because of the enhanced long-term fragrance retention ability. Our findings show the widespread potential of microcapsules synthesized from eco-friendly materials in industrial applications.