Photo-induced fusion of monodisperse polymer microspheres: A novel strategy for constructing topological microsphere clusters with improved stability

The preparation of monodisperse azobenzene (Azo) polymer microspheres by dispersion polymerization was reported. The photo-induced fusion of Azo polymer microspheres was successfully achieved during the process of reversible trans - cis - trans photoisomerization of Azo units, and induced various unique “microsphere molecular” clusters or “microsphere polymers”. Encouraged by this interesting phenomenon, microsphere clusters of different topological structures were stabilized by the in situ acetal cross-linking chemistry. The photo-induced fusion polymerization of monodisperse polymer microspheres provides a new strategy for designing photo-responsive clusters and allows for control over the mechanical properties of microspheres with high spatiotemporal resolution.