Soft Functionally Gradient Materials and Structures - Natural and Manmade: A Review.

TL;DR: In this paper , the basic design and functional principles of biological FGMs and their manmade counterparts using representative examples are discussed, and the challenges and potential pathways to leverage soft materials' facile processability and unique properties to ward functional FGMs.

Abstract: Functionally gradient materials (FGM) have gradual variations in their properties along one or more dimensions due to local compositional or structural distinctions by design. Traditionally, hard materials (e.g., metals, ceramics) have been used to design and fabricate FGMs; however, there has been increasing interest in polymer-based soft and compliant FGMs mainly because of their potential application in the human environment. Soft FGMs are not only ideally suitable to manage interfacial problems in dissimilar materials used in many emerging devices and systems for human interaction, such as soft robotics and electronic textiles and beyond. Soft systems are ubiquitous in our everyday lives; they are resilient and can easily deform, absorb energy and adapt to changing environments. Here, we discuss the basic design and functional principles of biological FGMs and their manmade counterparts using representative examples. The remarkable multifunctional properties of natural FGMs resulting from their sophisticated hierarchical structures, built from a relatively limited choice of materials, offer a rich source of new design paradigms and manufacturing strategies for manmade materials and systems for emerging technological needs. Finally, we highlight the challenges and potential pathways to leverage soft materials' facile processability and unique properties to wards functional FGMs. This article is protected by copyright. All rights reserved.