Designing nanoporosity in a swollen polymer for the controlled release of a highly volatile fragrance

• Published in: Flavour and fragrance journal Vol. 34; no. 2; pp. 124 - 132
• Main Authors: Chen, Xinwei, Bhardwaj, Ankit, Sharifah, Nursyahirah Syed Isha, Zhang, Liling, Man, Shu Mei, Andriani, Yosephine, Tan, Wui Siew
• Format: Journal Article
• Language: English
• Published: Chichester Wiley Subscription Services, Inc 01-03-2019
• Subjects: Acetic acid; Computer applications; Controlled release; diffusion; Evaporation; Evaporation rate; modulator; Perfumes; Polyurethane; Polyurethane resins; pore; Pore size; Porosity; Predictive control; UV‐curable resins
• ISSN: 0882-5734; 1099-1026
• DOI: 10.1002/ffj.3484

Controlling the fragrance release profile, especially the highly volatile top note, can prolong the desired scent of the fragrance. Here, the porosity of a swollen cross‐linked polyurethane acrylate (PUA) polymer, which is tuned by the length of a modulator, can influence the evaporation rate of the top note. In particular, the evaporation rate of benzyl acetate (BA), a common top note, is reduced by a factor of 6.5 (from 134 to 17 mg m–2 min–1) when BA is released from the best‐performing PUA against a reservoir of BA. The average diameter of an opening in the fragrance‐loaded PUA is ~6 nm, as determined by the thermoporosimetry approach. Such a pore size can effectively control the evaporation rate of BA, as predicted by the theoretical model, which reveals that a pore diameter of <16 nm is required. Computational modelling reveals the optimal chain length for a modulator used for the sustained released of fragrance, confirming the experimental data. Finally, BA continues to be released from the PUA matrix for a prolonged period, even after 3 months, whereas the same quantity of BA would completely evaporate after 1 week in the absence of PUA matrix. Approximately 50wt% of BA remains after 60 days, making it one of the best techniques in sustaining the release of a top note.
The free volume of a cross‐linked polymer can be designed to sustain the release of top notes of a fragrance. The evaporation rate of benzyl acetate (BA), a common top note, reduces by a factor of 6.5. This material of study can be processed using traditional methods or additive manufacturing, and can be applied for controlled released of compounds with small molecular weight.