Self-Densification of Highly Mesoporous Wood Structure into a Strong and Transparent Film.,Advanced Materials

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Self-Densification of Highly Mesoporous Wood Structure into a Strong and Transparent Film.
Advanced Materials ( IF 27.4 ) Pub Date : 2020-09-02 , DOI: 10.1002/adma.202003653
Kai Li _{1,

2} , Shennan Wang _{1,

2} , Hui Chen ₂ , Xuan Yang ₂ , Lars A Berglund ₂ , Qi Zhou _{1,

2}

Affiliation

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 m² g⁻¹ when prepared by freeze‐drying using liquid nitrogen, and 249 m² g⁻¹ by supercritical drying. These values are 5 to 7 times higher than conventional delignified wood (36 m² 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.

中文翻译：

高介孔木结构的自致密化成坚固透明的薄膜。

在天然木细胞壁中，纤维素微纤维高度排列并排列在次级细胞壁中。开发了一种新的制备策略，以实现木质细胞壁结构内纤维素微纤维的个体化，而不会引起机械崩解。将得到的介孔木结构具有197微米的高比表面积的²克^-1时通过冷冻干燥使用液氮制备，并且249米²克^-1通过超临界干燥。这些值是常规脱木素木（36 m ² g ^-1）的5至7倍）通过超临界干燥进行干燥。可以将这种高度介孔的结构保持个性化的纤维素微纤维的自然排列和组织，将其加工成具有高孔隙率和高抗压强度的气凝胶。此外，由于在水上的弹性毛细管力的作用下，纤维素微纤维的自致密化，仅通过空气干燥，即可获得沿纤维方向的拉伸强度为449.1±21.8 MPa和杨氏模量为51.1±5.2 GPa的坚固膜蒸发。由于纤维素微纤维的自然排列，自致密膜还显示出高光学透射率（80％）和高光学雾度（70％），以及令人感兴趣的双轴光散射行为。

更新日期：2020-10-20

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