Facile Synthesis of Alternating Azopolymers via Ugi Multicomponent Polymerization toward Photo- and pH-Responsive Polymersomes

Alternating azopolymers are notable in smart material design for their unique self-assembly behavior, which stems from the precisely controlled hydrophilic-hydrophobic balance and stimuli-responsiveness. Herein, we report the facile synthesis of light- and pH-responsive alternating copolymers, namely P(Azo-alt-PyEG₂tBu), via Ugi multicomponent polymerization using commercially available azobenzene and pyridine derivatives. P(Azo-alt-PyEG₂tBu) specifically self-assembled into polymersomes with ultrathin membranes (∼2.0 nm) through a folded chain model, serving as potential fluorescent probes when end groups are dye-modified. These polymersomes exhibit reversible morphological transitions between vesicles and micelles under alternating UV and blue light irradiation, driven by the azobenzene isomerization. Similarly, acidic pH triggers disassembly of the polymersomes due to protonation of pyridine groups. Light- and pH-triggered cargo-release studies reveal efficient encapsulation and controlled release of hydrophilic cargos. We have established a versatile strategy for constructing dual-responsive nanocarriers with tailored morphologies and stimuli-adaptive functionalities, advancing smart material applications in drug delivery and bioimaging.