Photo-Controlled Synthesis of Responsive Polymer Capsules from Hybrid Core-Shell Nanoparticles

摘要

Herein, we report for the first time the light-driven supramolecular engineering of water-dispersible polymer vesicles. The hollow capsules were controllably formed and ruptured by stimulating photosensitive, spherical polymer brushes on silica particles with the appropriate phototrigger. The polymer brushes were synthesized by surface-initiated atom transfer radical polymerization (ATRP) and consisted of dual-responsive 2-(dimethylamino)ethyl methacrylate (DMAEMA) and light-sensitive spiropyran (SP) moieties which undergo isomerization to merocyanine (MC) upon UV irradiation. Upon prolonged UV exposure of the sterically crowded polymer brushes, H-type π-π stacks are formed between the MC isomers, which act as physical cross-links between the polymer chains. After HF etching of the inorganic core, dual responsive polymeric vesicles are derived, whose walls’ robustness is provided by the H-type aggregates. The hydrophilic and pH-sensitive properties of the DMAEMA comonomer, facilitate the formation of the hollow capsules in water and their size manipulation via alteration of the solution pH, respectively. The inherent ability of the nanocapsules to fluoresce in water opens new avenues for the development of nanoscale capsules for biomedical applications. Finally, disruption of the stacks and thus the polymer vesicles can be achieved remotely using harmless visible-light irradiation.