Bi2S3纳米线的类聚合物构象和生长动力学,Journal of the American Chemical Society

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Bi2S3纳米线的类聚合物构象和生长动力学
Journal of the American Chemical Society ( IF 14.4 ) Pub Date : 2012-05-23 , DOI: 10.1021/ja301855z
Ludovico Cademartiri _{1,

2} , Gerald Guerin ₁ , Kyle J. M. Bishop ₃ , Mitchell A. Winnik ₁ , Geoffrey A. Ozin ₁

Affiliation

一维无机晶体（即晶体纳米线）是过去二十年来研究最深入的一类材料。尽管付出了巨大的努力，但一个重要的问题尚未得到解答：随着直径逐渐减小，纳米线是否显示出聚合物的一些独特特性？这项工作通过关于超薄 Bi(2)S(3) 纳米线的生长和形式的三个显着发现解决了这个问题。(i) 它们在溶液中的结晶可定量地描述为一种活性逐步生长聚合形式：在纳米线末端添加“单体”和完全形成的纳米线“端到端”耦合的明显独特的组合，终止和启动可忽略不计。(ii) 这两个主要过程的速率常数与聚合中发现的类似过程的速率常数相当。(iii) 这些纳米线的构象被定量描述为蠕虫状构象，在分析上类似于半柔性聚合物，其特征是持续长度为 17.5 nm（比双链 DNA 短）和数百微米的轮廓长度（比大多数合成聚合物长）。这些发现并没有证明晶体和聚合物之间的化学类比（尚不清楚单体是否是一个分子实体），但证明了结晶和聚合之间的物理类比。具体来说，

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Polymer-like Conformation and Growth Kinetics of Bi2S3Nanowires

One-dimensional inorganic crystals (i.e., crystalline nanowires) are one of the most intensely investigated classes of materials of the past two decades. Despite this intense effort, an important question has yet to be answered: do nanowires display some of the unique characteristics of polymers as their diameter is progressively decreased? This work addresses this question with three remarkable findings on the growth and form of ultrathin Bi(2)S(3) nanowires. (i) Their crystallization in solution is quantitatively describable as a form of living step-growth polymerization: an apparently exclusive combination of addition of "monomer" to the ends of the nanowires and coupling of fully formed nanowires "end-to-end", with negligible termination and initiation. (ii) The rate constants of these two main processes are comparable to those of analogous processes found in polymerization. (iii) The conformation of these nanowires is quantitatively described as a worm-like conformation analytically analogous to that of semiflexible polymers and characterized by a persistence length of 17.5 nm (shorter than that of double-stranded DNA) and contour lengths of hundreds of micrometers (longer than those of most synthetic polymers). These findings do not prove a chemical analogy between crystals and polymers (it is unclear if the monomer is a molecular entity tout court) but demonstrate a physical analogy between crystallization and polymerization. Specifically, they (i) show that the crystallization of ensembles of nanoscale inorganic crystals can be conceptually analogous to polymerization and can be described quantitatively with the same experimental and mathematical tools, (ii) demonstrate that one-dimensional nanocrystals can display topological characteristics of polymers (e.g., worm-like conformation in solution), (iii) establish a unique experimental model system for the investigation of polymer-like topological properties in inorganic crystals, and (iv) provide new heuristic guidelines for the synthesis of polymer-like nanowires.

更新日期：2012-05-23

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