Photoregulated Morphological Transformation of Spiropyran Derivatives Achieving the Tunability of Interfacial Hydrophilicity

Regulation of self-assembly morphology is an effective strategy to obtain advanced functional materials with expected properties. However, achieving remarkable morphological transformation by light irradiation is still a challenge. Herein, three simple spiropyran derivatives (SP1, SP2, and SP3) are constructed, achieving different degrees of morphological transformation from nanospheres to hollow tadpole-like structures (SP3), tubular structures (SP2), and microsheets (SP1) after ultraviolet light irradiation. Interestingly, the hollow tadpole-like structures (SP3) can further extend to Y-shaped or T-shaped tubular morphology. In the process, SP1, SP2, and SP3 can be isomerized from a closed-ring form (hydrophobicity) to an open-ring form (hydrophilicity) in different degrees, interacting differently with methanol solvent molecules. The formation of hollow structures or microsheets along with the isomerization of spiropyran derivatives contributes to the adjustment of the hydrophilicity of the interface. Therefore, SP1, SP2, and SP3 with photoregulated morphological transformation show promising applications in tunable interface materials.