Formulation of polyphthalaldehyde microcapsules for immediate UV-light triggered release
Journal article, 2020

Triggered release from responsive drug reservoirs activated by remote stimuli is desired in a range of fields. Critical bottlenecks are cost-efficient formulation avenues applicable for industrial scale-up, viable triggers and immediate release rather than continuous release upon activation. UV-sensitive microcapsules based on self-immolating polymers in combination with thin shells and morphological weak spots should allow for immediate triggered release. Polyphthalaldehyde-based microcapsules were prepared using several variations of the internal phase separation route. In addition, a fluorescence microscopy method was developed to study both the microcapsule morphology and the triggered release in-situ. The microcapsule formation was driven by the surface activity of the stabilizer, effectively lowering the high polymer-water interfacial tension, which is in sharp contrast to conventional encapsulation systems. Contrary to previous findings, a core–shell morphology was obtained via slow emulsion-to-suspension transformation. Rapid transformation captured intermediate inverted core–shell structures. The capsules were highly sensitive to both acid- and UV-mediated triggers, leading to an unzipping and rupturing of the shell that released the core content. Poly(methacrylic acid)-stabilized microcapsules displayed immediate UV-triggered release provided by their stimuli-sensitive blueberry morphology. Both capsules in aqueous and dry environment started to lose their core content after less than one minute of UV light exposure.


Internal phase separation

Core–shell particle

Triggered release


Viktor Eriksson

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry

Markus Andersson Trojer

RISE Research Institutes of Sweden

Szilvia Vavra

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry

Mats Hulander

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry

Lars Nordstierna

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry

Journal of Colloid and Interface Science

0021-9797 (ISSN) 1095-7103 (eISSN)

Vol. 579 645-653

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Polymer Chemistry

Physical Chemistry

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