The mechanical actuation of smart materials has garnered considerable attention in biological and medical research due to their ability to mimic biological processes at both molecular level, such as conformational changes in individual compounds, and at the macroscopic level, where polymeric substrates respond to external stimuli. In this study, we present a polymeric composite incorporating a novel urea macrocycle as a filler, forming a soft actuator that responds to various organic solvent vapors. The underlying actuation mechanism is attributed to crystalline phase transition of urea macrocycle, driven by the host‒guest interactions with diverse guest molecules. This work provides valuable insights for advancing the design of supramolecular hosts in smart material applications.

An Organic Vapor‐Responsive Actuator Based on a Novel Urea Macrocycle