Self-Assembly and Photoresponsivity Property of Amphiphilic ABA Triblock Copolymers Containing Azobenzene Moieties in Dilute Solution

The self-assembly and photoresponsivity of amphiphilic azobenzene-containing ABA triblock copolymers PA6C(m)-b-PEG(n)-b-PA6C(m) synthesized by atom transfer radical polymerization (ATRP) were reported. Different self-assembly morphologies formed by the gradual addition of water to the copolymer solutions in THF. The formation process and aggregate morphology were characterized by UV-Visible spectroscopy and transmission electron microscope (TEM). The triblock copolymers start to form aggregates at the critical water content (CWC). With the addition of water, the aggregates show different morphologies, such as spherical micelles, vesicles, network-like aggregates, and colloidal spheres, which involves the transformation between primary and secondary aggregates and the association/disassociation of aggregates. Photoresponsive property and aggregation behavior of these copolymers in solution under UV-Visible light irradiation were also investigated.