Shape-changing polymer assemblies

A panoply of stimuli-sensitive polymorphic polymer assemblies has been constructed through the intentional synthesis of amphiphilic block copolymers comprising hydrophilic, stimulus-responsive, and hydrophobic blocks. Transformations among canonical micellar forms of polymer assemblies-spherical micelles, wormlike micelles, and vesicles (polymersomes)-have been demonstrated with a number of synthetic systems. This review discusses recent progress in the development and understanding of these systems with a focus on open questions about kinetics of shape change, effects of block copolymer architecture on the rate and nature of the transformation, and potential applications. Factors that influence structural evolution of block copolymer assemblies that undergo stimulus-induced changes in shape and size are discussed.