Molecular actuators that can convert chemical stimuli into mechanical motion have attracted considerable attention due to their flexibility, adaptability and high energy density. Molecular actuators capable of performing complex mechanical motion are highly sought after for the development of the next-generation smart robotics. Nevertheless, none of the molecular actuators reported to date have achieved multiple actuation modes using chemical triggers. To overcome this limitation, we present a responsive composite film that displays distinct actuation modes when exposed to organic vapor. This material was readily prepared and scaled up by incorporating novel urea cage compounds into a polymer matrix. Through a comprehensive investigation into the molecular mechanism, we demonstrated that this exceptional actuation behaviour arises from the polymorphic transformations of the crystalline urea cages, which are triggered by selective host‒guest interactions. Moreover, by manipulating the type and concentration of the vapor stimuli, we can precisely control the mechanical motion of the actuator to accomplish various tasks. Undoubtedly, this multi-tasking and molecularly controlled actuator holds great promise in a wide range of state-of-the art applications, including wearable devices and soft robotics.
Niveen Khashab
Physical Sciences and Engineering Division, KAUST