Light‐Triggered Reversible Swelling of Azobenzene‐Containing Block Copolymer Worms via Confined Deformation Prepared by Polymerization‐Induced Self‐Assembly

Abstract

Stimuli‐responsive block copolymer nanoparticles (NPs) have received close attention in recent years owing to their tremendous application potential in smart materials. Azobenzene‐containing NPs are widely studied due to the advantages of light as a stimulus and fast reversible trans–cis isomerization of azobenzene chromophores. However, the inefficient preparation process and difficult reversible transformation of morphologies limit their development. Herein it is demonstrated that the light‐triggered reversible swelling behavior of wormlike NPs with high azobenzene content could be realized via confined deformation. These worms are prepared in large quantities via polymerization‐induced self‐assembly based on the copolymerization of 11‐(4‐(4‐butylphenylazo)phenoxy)undecyl methacrylate (MAAz) and N‐(methacryloxy)succinimide (NMAS) monomers. Upon UV/visible light irradiation, the reversible deformation of worms is achieved when the feed molar ratio of NMAS/MAAz is relatively high or via crosslinking using diamines, which leads to the reduction of the photoisomerization efficiency. The diameter variation of the worms is influenced by the amount and types of crosslinkers. Moreover, the scalability of this strategy is further proved by the fabrication of photo‐ and reductant‐responsive crosslinked worms. It is expected that this study not only provides a new route to affording reversible photoresponsive NPs but also offers a unique insight into the reversible photodeformation mechanism of azobenzene‐containing NPs.

Photoresponsive Block Copolymer Nanostructures through Implementation of Arylazopyrazoles

“…The amphiphilic epoxy-based alternating azo copolymer can assemble in water into colloidal spheres that transform into ellipsoids under irradiation with 488 nm laser. Another recent example by Deng et al shows the reversible swelling of cylindrical micelles . In this work, azobenzene-containing BCPs underwent a confined deformation upon irradiation.…”

“…Another recent example by Deng et al shows the reversible swelling of cylindrical micelles. 41 has also been reported that assembled alternating copolymers or BCP structures containing azobenzene can be disassembled and reassembled by irradiation. 28,42−45 In this study, we report AAP-bearing amphiphilic BCPs capable of forming different assemblies in solution upon photoisomerization of the AAP.…”