A Novel Photoresponsive Azobenzene-Containing Miktoarm Star Polymer: Self-Assembly and Photoresponse Properties

We report the synthesis and characterization of a novel azobenzene-containing miktoarm star polymer AB(3) (M-n = 9700 g mol(-1), D-M = 1.10) as well as its self-assembly properties in water. The miktoarm copolymer is composed of a hydrophobic azopolymer and three hydrophilic PEG arms (M-n = 600 g mol(-1)). The hydrophobic/hydrophilic ratio of the amphiphilic miktoarm polymer is 78/22, leading to the formation of stable polymeric vesicles in water evidenced via TEM and cryo-TEM imaging. The photoresponse of these vesicles has been investigated by irradiation with UV light (lambda = 350-400 nm) causing the disruption of the self-assemblies. Encapsulation of both hydrophilic and hydrophobic fluorescent probes, i.e., Nile Red and Rhodamine B, and the use of light as an external stimulus to trigger the release of the probes have also been demonstrated.