UV-triggered encapsulation and release from polyelectrolyte microcapsules decorated with photoacid generators

Abstract

In the present study, a versatile layer-by-layer technique using polyelectrolyte multilayers (PEMs) was used to prepare microcapsules with walls containing photoacid generators (PAGs), which made them optically addressable. By exposure to UV light with a wavelength of 254 nm, the PAGs within the capsule walls were activated, which caused the release of protons from the capsules. This release of protons caused a decrease in the pH of the capsule solution, which then triggered a swelling of the microcapsules. The resulting microcapsules could be opened and closed via alternate repetition of exposure to UV light and washing with neutral water. Prolonged exposure led to a breakage of the capsules, which promoted a rapid release of the entrapped substances.