Reconfigurable single-material soft microstructures

Abstract

Living organisms are often equipped with integrated microscale architectures that actively modulate motion, transport, as well as optical and mechanical properties by means of dynamically adjusting microscale feature sizes, shapes, connectivities, and distributions in highly coordinated ways. The development of synthetic materials emulating nature to create multi-functional reconfiguration soft structures has promised applications in a wide range of fields. However, current efforts mostly rely on hierarchical multimaterial designs with elaborate macro-/meso-scale architectures, which often become difficult and even impractical at the microscale. In this dissertation, we develop new strategies and mechanisms for creating reconfigurable single-material soft microstructures through multiscale synergistic actions, whose complexity of deformation arises from the symmetry breakings from the interplay across the molecular (M) and architectural (A) scales that are elicited and modulated via external stimuli (S). To illustrate the potential for our design principle, we first show how diverse complex non-reciprocal trajectories can emerge, through bottom-up MSA self-regulation, in a minimalist, single-material micropost fabricated out of a photoresponsive liquid crystalline elastomer by a simple molding procedure. Next, we explore how the network interconnectivity of cellular microstructures can introduce an additional level of geometric regulation to the MA interplay, which unlocks unusual mechanical deformations. Furthermore, beyond shape alterations of microstructures, we delve deeper into strategies for transforming the fundamental topologies of cellular microlattices through orchestrated interactions of polymer softening/stiffening (M) and elastocapillary-assembly (SA). Overall, we emphasize that the inherent simplicity of our design guarantees superior robustness and applicability as compared to systems relying on sophisticated manufacturing and controls. We envision this material platform and fundamental understandings will provide insight into the future development of truly intelligent soft materials.