Programmable and Reversible Shape-Morphing Nanoassemblies by Synergistically Integrating Photobase Generators and pH-Responsive Polymers

Shape-morphing nanostructures have broad utility in a range of applications, such as biomedicine, sensors, microfluidics, and microrobotics. Considerable progress has been made in developing shape-transformable polymeric micelles that undergo deformation in response to stimuli. Nevertheless, it remains a considerable challenge to achieve programmable, reversible, and well-defined shifts in morphology. Herein, we reported a facile and efficient strategy to produce photocontrolled shape-transformable micelles by the integration of a reversible photobase generator (PBG) (Malachite green carbinol base, MGCB) into pH-responsive micelles, which are derived from the self-assembly of poly(2-(diethylamino) ethyl methacrylate) (PDEAEMA)-containing amphiphilic block copolymers (PDED). Under ultraviolet (UV) irradiation, the presence of MGCB in MGCB-loaded PDED NPs in water could quickly generate hydroxide ions (OH–), leading to an increase in the pH value and the subsequent deprotonation and hydrophobization of the PDEAEMA chain, finally achieving programmable deformation of PDED NPs. Importantly, the change in morphology of PDED NPs among spherical micelles, wormlike micelles, planar lamellae, and bicontinuous structures can be easily controlled by adjusting the UV irradiation time. Moreover, the original shape of MGCB-loaded PDED NPs can be switched back after stopping UV exposure, displaying a desirable reversibility in shape changes. Considering the easily available agents and simple preparation process as well as precise spatiotemporal control, the strategy designed herein provides a facile and universal approach to produce photocontrolled, reversible, switchable shape-morphing nanostructures.