Polymers Science in Modeling Mushy, Squishy Systems

Over the last few decades, there has been rapidly growing interest in soft, stimuli-responsive polymeric materials (“mushy, squishy systems”) that exhibit a global response to a local signal. One motivation for creating such polymers arises from a technological need to produce energy efficient devices that can amplify or convert a small-scale input into a large-scale action. Another inspiration for focusing on responsive polymers comes from biology. One of the exquisitely evolved properties of biological systems is the ability to convert local information into a global action. Few synthetic materials can match the ability of biological systems to undergo large-scale, rapid motion in response to local changes. There are a number of design challenges that must be met in order to create such efficient systems. First, the polymeric material must be capable of not only sensing a local signal, but also reacting in a specified manner. Second, the polymers should ideally be capable of transducing one form of energy (e.g., electromagnetic, optical, chemical) into a mechanical action and thus must be “active”. Developing such responsive polymeric materials poses significant and intriguing scientific challenges, and necessitates the development of robust theoretical and computational models for the behavior of active materials systems. A few examples of these kinds of modeling approaches will be discussed, highlighting efforts that are valuable for developments in future technologies, such as soft robotics and autonomously operating devices.