Toward photocontrolled release using light-dissociable block copolymer micelles

A study on photocontrolled release of a model hydrophobic guest from light-dissociable polymer micelles, using a new dye-containing amphiphilic block copolymer (BCP), is presented. Tree types of micelles were prepared and utilized in the study. Polymer micelles without Nile Red (NR) were obtained in a mixed solvent of THF/water and used for all static light scattering experiments and related scanning electron microscopy observations. Fluorescence emission measurements show that NR encapsulated by the BCP micelles can be released upon irradiation as a result of the disruption of the BCP micelles. The rate of photoinduced release can be controlled by a number of means, particularly by varying the irradiation intensity that determines the rate of the photolysis reaction. The study reveals that micelles of the amphiphilic block copolymers comprising hydrophilic poly(ethylene oxide) can be dissociated by light via either one-photon UV or two-photon near infrared absorption.