Engineering Laboratory for Functionalized Carbon Materials and Shenzhen Key Laboratory for Graphene-based Materials, Graduate School at Shenzhen, Tsinghua University , The University Town, Shenzhen 518055, China.
Institute of Multidisciplinary Research for Advanced Materials, Tohoku University , 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan.
ACS Nano. 2016 Dec 27;10(12):10689-10697. doi: 10.1021/acsnano.6b05808. Epub 2016 Nov 9.
Honeycomb structures have been attracting attention from researchers mainly for their high strength-to-weight ratio. As one type of structure, honeycomb monoliths having microscopically dimensioned channels have recently gained many achievements since their emergence. Inspired by the microhoneycomb structure that occurs in natural tree xylems, we have been focusing on the assembly of such a structure by using the major component in tree xylem, cellulose, as the starting material. Through the path that finally led us to the successful reconstruction of tree xylems by the unidirectional freeze-drying (UDF) approach, we verified the function of cellulose nanofibers, toward forming xylem-like monoliths (XMs). The strong tendency of cellulose nanofibers to form XMs through the UDF approach was extensively confirmed with surface grafting or a combination of a variety of second components (or even a third component). The resulting composite XMs were thus imparted with extra properties, which extends the versatility of this kind of material. Particularly, we demonstrated in this paper that XMs containing reduced graphene oxide (denoted as XM/rGO) could be used as strain sensors, taking advantage of their penetrating microchannels and the bulk elasticity property. Our methodology is flexible in its processing and could be utilized to prepare various functional composite XMs.
蜂窝结构因其高比强度而引起了研究人员的关注。作为一种结构，具有微观尺寸通道的蜂窝整体结构最近取得了许多成就，因为它们的出现。受天然树木木质部中存在的微蜂窝结构的启发，我们一直专注于使用树木木质部中的主要成分纤维素作为起始材料来组装这种结构。通过最终使我们能够通过单向冻干 (UDF) 方法成功重建树木木质部的途径，我们验证了纤维素纳米纤维的功能，以形成木质部样整体结构 (XMs)。纤维素纳米纤维通过 UDF 方法形成 XMs 的强烈趋势得到了广泛证实，通过表面接枝或结合各种第二组分（甚至第三组分）。由此得到的复合 XMs 因此赋予了额外的特性，从而扩展了这种材料的多功能性。特别是，我们在本文中证明了含有还原氧化石墨烯的 XMs（表示为 XM/rGO）可以用作应变传感器，利用其贯穿的微通道和整体弹性特性。我们的方法在处理方面具有灵活性，可用于制备各种功能复合 XMs。
