層狀二維分子編織物的自組裝
作者:
小柯機器人發布時間:2020/12/19 15:46:25
曼徹斯特大學David A. Leigh等近日取得一項新成果。經過不懈努力,他們通過自組裝構建了類似編織物的層狀二維分子網格結構。 這一研究成果發表在2020年12月16日出版的國際學術期刊《自然》上。
在本文中,研究人員報導了一種超分子二維Kagome型編織物和一種表面支撐的單層交織二維聚合物材料。此前,由分子模塊自下而上直接組裝成線性有機高分子鏈然後編成的二維聚合物已在一些報導中被設計過,但從未真正被成功合成過。
這裡,研究人員通過使用一個含陰離子和金屬離子的模板,將「分子絲」橫豎編成由脂肪鏈和芳香烴交替排列的聚合物股,然後在分立的層中交織。通過緩慢沉澱的預編格子間形成的連接,以及之後離子模板的移除,研究人員得到了一種以薄層堆積成的全有機分子材料,每一層有數百微米長寬但只有約四納米厚,其中縱橫的聚合物單鏈通過層中周期性的機械互鎖結合在一起。
用原子力顯微鏡和掃描電子顯微鏡對其團簇和一些獨立的層的分析表明,在去金屬化後,原來交織聚合過程中產生的層間堆積已發生滑動。這一層狀二維分子編織材料具有長程有序性,具有雙折射性,其韌性是構成其的線性聚合物的兩倍,並沿著一條明確的線像宏觀編織物那樣被撕裂。當被整合到一個聚合物支撐的膜中時,該材料就像一張網一樣,可以讓小離子自由穿透的同時減慢大離子的通過。
據介紹,包含多層編制纖維的紡織物是日常生活中最重要的材料之一。以往的納米編織物主要包括在三個維度上由剛性螺旋股纏繞的各向同性晶態共價有機框架化合物,但具有類似傳統編織物的柔性、超薄、各向異性和多孔紋理的二維層狀柔性編織物較少被報導。
附:英文原文
Title: Self-assembly of a layered two-dimensional molecularly woven fabric
Author: David P. August, Robert A. W. Dryfe, Sarah J. Haigh, Paige R. C. Kent, David A. Leigh, Jean-Franois Lemonnier, Zheling Li, Christopher A. Muryn, Leoni I. Palmer, Yiwei Song, George F. S. Whitehead, Robert J. Young
Issue&Volume: 2020-12-16
Abstract: Fabrics—materials consisting of layers of woven fibres—are some of the most important materials in everyday life. Previous nanoscale weaves include isotropic crystalline covalent organic frameworks that feature rigid helical strands interlaced in all three dimensions, rather than the two-dimensional layers of flexible woven strands that give conventional textiles their characteristic flexibility, thinness, anisotropic strength and porosity. A supramolecular two-dimensional kagome weave and a single-layer, surface-supported, interwoven two-dimensional polymer have also been reported. The direct, bottom-up assembly of molecular building blocks into linear organic polymer chains woven in two dimensions has been proposed on a number of occasions, but has not previously been achieved. Here we demonstrate that by using an anion and metal ion template, woven molecular 『tiles』 can be tessellated into a material consisting of alternating aliphatic and aromatic segmented polymer strands, interwoven within discrete layers. Connections between slowly precipitating pre-woven grids, followed by the removal of the ion template, result in a wholly organic molecular material that forms as stacks and clusters of thin sheets—each sheet up to hundreds of micrometres long and wide but only about four nanometres thick—in which warp and weft single-chain polymer strands remain associated through periodic mechanical entanglements within each sheet. Atomic force microscopy and scanning electron microscopy show clusters and, occasionally, isolated individual sheets that, following demetallation, have slid apart from others with which they were stacked during the tessellation and polymerization process. The layered two-dimensional molecularly woven material has long-range order, is birefringent, is twice as stiff as the constituent linear polymer, and delaminates and tears along well-defined lines in the manner of a macroscopic textile. When incorporated into a polymer-supported membrane, it acts as a net, slowing the passage of large ions while letting smaller ions through.
DOI: 10.1038/s41586-020-3019-9
Source: https://www.nature.com/articles/s41586-020-3019-9