Carbon Dioxide-Switchable Polymers: Where Are the Future Opportunities?

Carbon dioxide has emerged as a new and innovative trigger for stimuli-responsive materials. It is abundant, inexpensive, nontoxic, and environmentally benign. Carbon dioxide-switchable polymers are a class of stimuli-responsive polymers for which CO2 is a trigger used to reversibly switch the polymer properties, typically from hydrophobic (in the absence of CO2) to hydrophilic (in the presence of CO2). Recent years have witnessed a surge in interest in polymers incorporating CO2-switchable moieties, where the change in properties upon switching has enabled the development of a new generation of stimuli-responsive materials, including switchable particles, surfaces, catalysts, and a plethora of nonspherical polymer particle morphologies such as wormlike micelles, vesicles, tubules, and gels. This Perspective introduces the principles of CO2-switching, highlights recent major developments, and presents our personal insights into challenges with commercialization of CO2-switchable polymers and future opportunities for new research directions and materials applications.