Wood elasticity and compressible wood-based materials: Functional design and applications

The typical strength of wood makes it suitable as a structural material. Under load, natural wood exhibits a small strain within the elastic range. Such elasticity is associated with fast recovery materials, which hold relevance to applications that include piezoelectric sensors and actuators, bionic systems, soft robots and artificial muscles. Any progress to advance such advanced functions requires control on the hierarchical structure of wood as well as the multiscale and multicomponent interactions affecting its elasticity and compressibility. Herein, we review the key structural features, from the molecular to the macroscopic levels, that define wood elasticity and compressibility. They relate to the assembly pattern of wood's lignocellulosic components, corresponding helical arrangement in the cell wall, and the anisotropy that controls the elastic and compression properties. We summarize the research progress achieved so far in the area, exploring the origins and feasible routes to modulate wood compressibility. Finally, we provide critical perspective on future impact of the area along with new applications of wood-based structures that take advantages of their latent elasticity.