Viewpoint: From Responsive to Adaptive and Interactive Materials and Materials Systems: A Roadmap

Abstract

toward higher levels of complexity and takes increasing inspiration from the concepts of living species, it feels imminent and of high importance to foster the discussion on this topic and provide a roadmap to evolve synthetic systems from responsive to adaptive and interactive systems and materials. This is not only important in the context of highlighting landmark advances of future systems over present ones, but also relevant for the education of the next generation of researchers going to operate in the field. Furthermore, we are often faced with an inadequate inflation of terminology, which may also not help to develop new conceptual research directions in a clear manner.It is the objective of this Viewpoint to discuss relevant conceptual differences between these material classes (responsive vs adaptive vs interactive) in a generally accessible way-albeit certainly from a personal perspective-and fertilize and contribute to this discussion, and hopefully provide some definitions and a roadmap for future materials system design. Given the brevity of this viewpoint, it will only relate at selected places shortly to some existing literature, but has the main objective on communicating concepts underlying advanced adaptivity and interactivity. Responsive SystemsLet us first look back at the class of stimuli-responsive materials, which have been an outstanding success story for the design of advanced switchable soft materials that continue to widely Soft matter systems and materials are moving toward adaptive and interactive behavior, which holds outstanding promise to make the next generation of intelligent soft materials systems inspired from the dynamics and behavior of living systems. But what is an adaptive material? What is an interactive material? How should classical responsiveness or smart materials be delineated? At present, the literature lacks a comprehensive discussion on these topics, which is however of profound importance in order to identify landmark advances, keep a correct and noninflating terminology, and most importantly educate young scientists going into this direction. By comparing different levels of complex behavior in biological systems, this Viewpoint strives to give some definition of the various different materials systems characteristics. In particular, the importance of thinking in the direction of training and learning materials, and metabolic or behavioral materials is highlighted, as well as communication and information-processing systems. This Viewpoint aims to also serve as a switchboard to further connect the important fields of systems chemistry, synthetic biology, supramolecular chemistry and nano-and microfabrication/3D printing with advanced soft materials research. A convergence of these disciplines will be at the heart of empowering future adaptive and interactive materials systems with increasingly complex and emergent life-like behavior.

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