Light-Controlling Janus Micro-Nanoparticles Satellite-Like Structure Self-Assembly by Azobenzene/Cyclodextrin Host-Guest Interaction

Stimuli-responsive Janus micro- and nanoparticles are drawing more and more attention from scientific research personnel due to its controllable, reversible and inhomogeneous change of surface properties under the external stimuli. However, there are few researches on Janus micro- and nanoparticles with switchable physical structure under external stimuli (especially light irradiation). In this work, we have fabricated SiO₂ Au-Azo Janus microparticles and SiO₂-Azo nanoparticles by introducing azobenzene (Azo) radicals onto the particle surface through surface chemical modification. Then α-cyclodextrin (α-CD) is grafted onto polyacrylic acid (PAA) chain gragment to synthesize the main polymer PAA-α-CD. With the help of Azo/CD host-guest interactions, Janus micro- and nanoparticles satellite-like structure can be formed between SiO₂|Au-Azo Janus microparticles and SiO₂-Azo nanoparticles. Under the UV light irradiation, the trans-cis isomerization of Azo can further decompose the satellite-like structure. The satellite-like structure can be reformed under green-light irradiation. Therefore, light-controlling of Janus micro- and nanoparticles satellite-like structure self-assembly is realized, which is expected to be applied in fabricating precise and orderly micro-nano 3D structure.