Shi Xuetong, Bi Ran, Wan Zhangmin, Jiang Feng, Rojas Orlando J
Bioproducts Institute, Department of Chemical & Biological Engineering, The University of British Columbia, 2360 East Mall, Vancouver, British Columbia V6T 1Z3, Canada.
Sustainable Functional Biomaterials Laboratory, Department of Wood Science, The University of British Columbia, Vancouver, British Columbia V6T 1Z4, Canada.
ACS Nano. 2024 Mar 19;18(11):7959-7971. doi: 10.1021/acsnano.3c10650. Epub 2024 Mar 4.
The methods used to date to produce compressible wood foam by top-down approaches generally involve the removal of lignin and hemicelluloses. Herein, we introduce a route to convert solid wood into a super elastic and insulative foam-like material. The process uses sequential oxidation and reduction with partial removal of lignin but high hemicellulose retention (process yield of 72.8%), revealing fibril nanostructures from the wood's cell walls. The elasticity of the material is shown to result from a lamellar structure, which provides reversible shape recovery along the transverse direction at compression strains of up to 60% with no significant axial deformation. The compressibility is readily modulated by the oxidation degree, which changes the crystallinity and mobility of the solid phase around the lumina. The performance of the highly resilient foam-like material is also ascribed to the amorphization of cellulosic fibrils, confirmed by experimental and computational (molecular dynamics) methods that highlight the role of secondary interactions. The foam-like wood is optionally hydrophobized by chemical vapor deposition of short-chained organosilanes, which also provides flame retardancy. Overall, we introduce a foam-like material derived from wood based on multifunctional nanostructures (anisotropically compressible, thermally insulative, hydrophobic, and flame retardant) that are relevant to cushioning, protection, and packaging.
通过自上而下的方法制备可压缩木泡沫通常采用的方法一般涉及去除木质素和半纤维素。在此，我们介绍一种将实木转化为超弹性且绝缘的泡沫状材料的途径。该过程采用顺序氧化和还原，部分去除木质素但高保留半纤维素（工艺产率为72.8%），揭示了木材细胞壁的原纤纳米结构。材料的弹性源于层状结构，在高达60%的压缩应变下，该结构沿横向提供可逆的形状恢复，且无明显轴向变形。压缩性可通过氧化程度轻松调节，氧化程度会改变管腔周围固相的结晶度和流动性。这种高弹性泡沫状材料的性能还归因于纤维素原纤的非晶化，实验和计算（分子动力学）方法证实了这一点，这些方法突出了二级相互作用的作用。通过短链有机硅烷的化学气相沉积可选择性地使泡沫状木材疏水，这也提供了阻燃性。总体而言，我们介绍了一种基于多功能纳米结构（各向异性可压缩、隔热、疏水和阻燃）的源自木材的泡沫状材料，这些结构与缓冲、保护和包装相关。
