Photo-induced micellization of poly(4-pyridinemethoxymethylstyrene)-block-polystyrene using a photo-acid generator

The photo-induced micellization was attained for a poly(4-pyridinemethoxymethylstyrene)-block-polystyrene diblock copolymer using diphenyliodonium hexafluorophosphate, a photo-acid generator. Dynamic light scattering demonstrated that the copolymers with a 27.2-nm hydrodynamic diameter self-assembled into micelles with a 68.9-nm diameter by irradiation of a 1,4-dioxane solution of the copolymer using a high-pressure mercury lamp. The micellization was completed within 5 h based on the variation in the scattering intensity and the hydrodynamic diameter of the copolymer. It was found that the copolymer formed monodispersed spherical micelles because G₁(τ), the normalized time correlation function of the scattered field, showed a linear decay. Furthermore, the proton nuclear magnetic resonance analysis confirmed that the micelles had cores formed by the poly(4-pyridinemethoxymethylstyrene) blocks. It was suggested that the micellization occurred by electron transfer from the pyridine to the photo-acid generator in their excited states.