Nanostructurally Controllable Strong Wood Aerogel toward Efficient Thermal Insulation

Abstract

Eco-friendly materials with superior thermal insulation and mechanical properties are desirable for improved energy- and space-efficiency in buildings. Cellulose aerogels with structural anisotropy could fulfill these requirements, but complex processing and high energy demand are challenges for scaling up. Here we propose a scalable, nonadditive, top-down fabrication of strong anisotropic aerogels directly from wood with excellent, near isotropic thermal insulation functions. The aerogel was obtained through cell wall dissolution and controlled precipitation in lumen, using an ionic liquid (IL) mixture comprising DMSO and a guanidinium phosphorus-based IL [MTBD][MMP]. The wood aerogel shows a unique structure with lumen filled with nanofibrils network. In situ formation of a cellulosic nanofibril network in the lumen results in specific surface areas up to 280 m 2 /g and high yield strengths >1.2 MPa. The highly mesoporous structure (average pore diameter ∼20 nm) of freeze-dried wood aerogels leads to low thermal conductivities in both the radial (0.037 W/mK) and axial (0.057 W/mK) directions, showing great potential as scalable thermal insulators. This synthesis route is energy efficient with high nanostructural controllability. The unique nanostructure and rare combination of strength and thermal properties set the material apart from comparable bottom-up aerogels. This nonadditive synthesis approach is believed to contribute significantly toward large-scale design and structure control of biobased aerogels.

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

“…Intriguingly, the carbohydrate, lignin, ash, and extractive analysis showed relatively unchanged chemical composition (Figure 2m). Lignin, hemicellulose, and cellulose contents of the NW-Aerogel were 21, 20, and 57 wt %, respectively, which are similar to those of NW (22,21, and 53 wt %, respectively). A mass balance of the wood treatment can be seen in Table S1 of the Supporting Information.…”

Advancing Hydrovoltaic Energy Harvesting from Wood through Cell Wall Nanoengineering

“…This is a great improvement considering materials efficiency compared to ≈50% weight loss in the previously reported works. [14] Relative hemicellulose content decreased 4 wt.% for NBa-NaOH compared with NBa, whereas DW-NaOH only had ≈1 wt.% remaining (Figure 2f). On the other hand, NBi-NaOH exhibits no reduction in hemicellulose, this could be due to limited penetration of the thick cell walls of NBi.…”

“…Previously, we developed a non-additive strategy to improve wood surface area and permeability via cell wall nano engineering, partial dissolution of the wood cell wall, and transfer of biopolymers to the lumen in the form of nano structured networks. [14] In pursuit of eco-friendly materials, a shift to greener chemicals is necessary. One of the most benign is the water/NaOH system, which has cellulose dissolution capabilities at sub-zero temperatures.…”

Recent advances in flexible and soft gel-based pressure sensors

“…Gels are flexible and soft materials consisting of three-dimensional (3D) crosslinked polymer networks (solid content) and numerous internal open pores filled with either solvents (liquid content, e.g., hydrogels [30][31][32] and ionogels [33][34][35] ) or air (gas content, e.g., aerogels [36][37][38] ) [39][40][41] . Due to the framework of strong bonding between polymer chains and the redundant space of internal open pores for deformation, hydrogels and ionogels exhibit an intrinsic nature of superior flexibility and stretchability.…”

“…Copyright 2019, American Chemical Society)) and aerogels (e.g., lightweight aerogels (reproduced with permission [36] . Copyright 2018, WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim), highly porous aerogels (reproduced with permission [37] . Copyright 2022, American Chemical Society) and thermally insulating aerogels (reproduced with permission [38] .…”