A supramolecular approach for fabrication of photo-responsive block-controllable supramolecular polymers

Self-assembly of stimuli-responsive block copolymers in aqueous solution has attracted considerable attention in the past few decades. Herein, we report a supramolecular modular synthetic approach for the fabrication of photo-responsive block-controllable supramolecular polymers (BSPs) based on the assembly of two homopolymers in water. The homopolymers, namely, the polystyrene modified with adamantane and azobenzene as the end groups (Ad–PS–Azo) and poly(ethylene glycol) modified with β-CD (PEG–β-CD), were successfully synthesized via atom transfer radical polymerization (ATRP) and click chemistry, respectively. The supramolecular triblock copolymer (STP) was constructed through host–guest interactions between β-CD and Ad/Azo moieties, and further self-assembled into micelles in aqueous solution, which were investigated by transmission electron microscopy (TEM) and dynamic light scattering (DLS). This well-defined supramolecular triblock copolymer can reversibly disassemble into a supramolecular diblock copolymer (SDP) by alternating irradiation of UV/visible light, which was revealed by TEM, UV-vis and 1H NMR.