Recent advances and challenges in designing stimuli-responsive polymers

Synthetic materials capable of responses to external or internal stimuli represent one of the most exciting and emerging areas of scientific interest and unexplored commercial applications. While there are many exciting challenges facing this field, there are a number of opportunities in design, synthesis, and engineering of stimuli-responsive polymeric systems and Mother Nature serves as a supplier of endless inspirations. This review examines physico-chemical requirements necessary to achieve stimuli-responsiveness in heterogeneous polymer networks as well as discusses recent developments and future trends. While individual structural components of polymeric networks are responsible for localized chain-responsiveness, desirable spatial and energetic network properties are necessary for collective and orchestrated responsiveness to external or internal stimuli. These attributes significantly vary for stimuli-responsive polymeric solutions, surfaces and interfaces, polymeric gels, and solid networks.