Strong, Shape-Memory Lignocellulosic Aerogel via Wood Cell Wall Nanoscale Reassembly

Polymer shape-memory aerogels (PSMAs) are prospects in various fields of application ranging from aerospace to biomedicine, as advanced thermal insulators, actuators, or sensors. However, the fabrication of PSMAs with good mechanical performance is challenging and is currently dominated by fossil-based polymers. In this work, strong, shape-memory bio-aerogels with high specific surface areas (up to 220 m²/g) and low radial thermal conductivity (0.042 W/mK) were prepared through a one-step treatment of native wood using an ionic liquid mixture of [MTBD]⁺[MMP]^-/DMSO. The aerogel showed similar chemical composition similar to native wood. Nanoscale spatial rearrangement of wood biopolymers in the cell wall and lumen was achieved, resulting in flexible hydrogels, offering design freedom for subsequent aerogels with intricate geometries. Shape-memory function under stimuli of water was reported. The chemical composition and distribution, morphology, and mechanical performance of the aerogel were carefully studied using confocal Raman spectroscopy, AFM, SAXS/WAXS, NMR, digital image correlation, etc. With its simplicity, sustainability, and the broad range of applicability, the methodology developed for nanoscale reassembly of wood is an advancement for the design of biobased shape-memory aerogels.