Silica replication of the hierarchical structure of wood with nanometer precision

Abstract

The structural features of wood were replicated in silica on all levels of hierarchy from the macroscopic to the nanoscopic level of the cellulose elementary fibrils. This was achieved by a series of processing steps on spruce wood templates. Sodium chlorite was used to partially remove the lignin matrix from the wood cell walls, exposing the cellulose fibrils. These were optionally functionalized with maleic acid anhydride to stabilize the fibrillar structure and reduce the shrinkage of the template. Repeated infiltration with tetraethyl orthosilicate in ethanol deposited silica on the fibrils. Calcination at 500°C removed the rest of the organic template by oxidation and resulted in the fusion of the deposited material into a positive silica replica. Small-angle x-ray scattering evidenced fibrillar structures parallel to the original cellulose fibrils at length scales in the order of 10 nm, suggesting the successful nanoscopic replication of the cellulose fibrils and their orientation.

Chemistry and water-repelling properties of phenyl-incorporating wood composites

“…In its monomeric state, TEOS can penetrate into cell walls (Saka et al 1992), whereas this is not possible for prehydrolyzed and precondensed siloxane species due to their larger molecular dimensions (Unger et al 2012). The penetration of TEOS into cell wall pores down to a size of as low as 1 nm was recently described by means of a combined delignification and chemical functionalization approach (Van Opdenbosch et al 2011;Fritz-Popovski et al 2013). If the presence of water is limited to the cell wall, hydrolysis and condensation (as shown in Figure 1a and b) will mainly occur within the cell wall.…”

Preparation of CaCO3 and CaO Replicas Retaining the Hierarchical Structure of SpruceWood

“…Also, a highly crystalline porous oxide material was produced by infiltrating a Ce 0.5 Zr 0.5 O 2 sol into the tissue of wood [20]. Furthermore, a nanoscopic replication of the cellulose fibril was successfully fabricated by infiltrating TEOS into delignified and functionalized spruce wood templates [15]. Using tailor-made precursor sols and salt solutions, hierarchically structured phosphor materials based on softwood could be fabricated [21 -23].…”

Cellular complexity captured in durable silica biocomposites

“…Inter-and intracellular heterogeneity from the nano-to macroscale is captured and dimensionally preserved in CSCs following drying and subjection to extreme temperatures allowing, for instance, size and shape preserving pyrolysis of cellular architectures to form conductive carbon replicas. The structural and behavioral malleability of the starting material (cultured cells) provides opportunities to develop robust and economical biocomposites with programmed structures and functions.sol-gel | biomineralization | biopreservation | frustule T he synthesis of inorganic materials with controlled and complex forms has been facilitated through discoveries such as vesicle, micelle, and liquid crystalline templating of silicates (1-3), which provided inspiration to explore a range of templating strategies based on self-assembled molecular precursors (4-8), colloids (9-11), and biological templates and vessels (12)(13)(14). A driving force for these efforts is the many complex inorganic structures found in nature.…”

“…sol-gel | biomineralization | biopreservation | frustule T he synthesis of inorganic materials with controlled and complex forms has been facilitated through discoveries such as vesicle, micelle, and liquid crystalline templating of silicates (1)(2)(3), which provided inspiration to explore a range of templating strategies based on self-assembled molecular precursors (4)(5)(6)(7)(8), colloids (9)(10)(11), and biological templates and vessels (12)(13)(14). A driving force for these efforts is the many complex inorganic structures found in nature.…”