Light-Triggered Reversible Slimming of Cross-linked Nanowires Synthesized by Polymerization-Induced Hierarchical Self-assembly and Photodimerization

Stimulus-responsive nanowires are attractive and expected to be used in diversified fields, but their application is usually affected by an inefficient synthetic process, impure morphologies, and unsteadiness in organic solvents. Meanwhile, the reversibility of the response is also challenging. Here, we present a new method incorporating polymerization-induced hierarchical self-assembly (PIHSA) and photodimerization to prepare cross-linked triblock copolymer nanowires, which were synthesized by the successive polymerization of methacrylate monomers containing azobenzene (MAAz) and stilbene (MAStb). The formation of nanowires was related to the highly ordered stacking of stilbene, and their heterostructures could be clearly identified by the distinct regions comprising azobenzene and stilbene at the periphery and center of the cores, respectively. Upon UV irradiation, the dimerization of stilbene cross-linked the structure and made the nanowires tolerant to good solvents. The cross-linked nanowires with appropriate block ratios were photoresponsive, which could reversibly expand and slim upon alternative UV/visible light irradiation due to the well-defined distribution of azobenzene and stilbene. This work will open a new door for the development and application of stimulus-responsive nanowires owing to their fascinating reversible deformation and distinguished stability.