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Self‐Densification of Highly Mesoporous Wood Structure into a Strong and Transparent Film
Author(s) -
Li Kai,
Wang Shennan,
Chen Hui,
Yang Xuan,
Berglund Lars A.,
Zhou Qi
Publication year - 2020
Publication title -
advanced materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 10.707
H-Index - 527
eISSN - 1521-4095
pISSN - 0935-9648
DOI - 10.1002/adma.202003653
Subject(s) - materials science , cellulose , ultimate tensile strength , mesoporous material , composite material , supercritical drying , bacterial cellulose , supercritical fluid , porosity , fiber , compressive strength , chemical engineering , biochemistry , chemistry , organic chemistry , engineering , catalysis
In the native wood cell wall, cellulose microfibrils are highly aligned and organized in the secondary cell wall. A new preparation strategy is developed to achieve individualization of cellulose microfibrils within the wood cell wall structure without introducing mechanical disintegration. The resulting mesoporous wood structure has a high specific surface area of 197 m 2 g −1 when prepared by freeze‐drying using liquid nitrogen, and 249 m 2 g −1 by supercritical drying. These values are 5 to 7 times higher than conventional delignified wood (36 m 2 g −1 ) dried by supercritical drying. Such highly mesoporous structure with individualized cellulose microfibrils maintaining their natural alignment and organization can be processed into aerogels with high porosity and high compressive strength. In addition, a strong film with a tensile strength of 449.1 ± 21.8 MPa and a Young's modulus of 51.1 ± 5.2 GPa along the fiber direction is obtained simply by air drying owing to the self‐densification of cellulose microfibrils driven by the elastocapillary forces upon water evaporation. The self‐densified film also shows high optical transmittance (80%) and high optical haze (70%) with interesting biaxial light scattering behavior owing to the natural alignment of cellulose microfibrils.