Nanorod position and orientation in vertical cylinder block copolymer films
Nanorod position and orientation in vertical cylinder block copolymer films
复制标题
垂直圆柱嵌段共聚物薄膜中纳米棒的位置和方向
DOI：
10.1039/d0sm00043d
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发表时间：
2020
期刊：
影响因子：
3.4
通讯作者：
Composto, Russell J.
中科院分区：
文献类型：
--
作者：
Rasin, Boris;Lindsay, Benjamin J.;Ye, Xingchen;Meth, Jeffrey S.;Murray, Christopher B.;Riggleman, Robert A.;Composto, Russell J.
研究了不同尺寸的金纳米棒与嵌段共聚物(BCP)的自组装行为。含有P2VP功能化AuNR的聚苯乙烯-嵌段-聚(2-乙烯基吡啶)(PS-b-P2VP)薄膜经溶剂热处理后，在PS基质中形成垂直的P2VP圆柱体的BCP形态。在PS-b-P2VP薄膜的表面，发现了长的AuNRs，分别处于桥联态和垂直态。桥联状态是AuNR的长轴平行于薄膜表面，AuNR嵌在薄膜中，AuNR的两端位于最近相邻的P2VP柱面的顶部。垂直状态是AuNR位于垂直的P2VP圆柱体内，AuNR长轴垂直于薄膜表面，AuNR的上尖端位于薄膜表面。在桥联态和垂直态以及在长AuNR(中心态)中没有观察到的状态中，发现了短AuNR。居中状态是指AuNR的长轴平行于薄膜表面，嵌入在薄膜中，并位于垂直的P2VP圆柱体的中心。模拟实验系统的混合粒子场理论(HPFT)模拟表明，对于长的AuNRs，只能观察到桥联状态，而对于短的AuNRs，只能观察到桥联和中心态。讨论了为什么在实验中观察到垂直态，尽管在模拟中热力学上是不利的，这是可能的。HPFT模拟还表明，当纳米棒处于桥联状态时，它连接的两个圆柱体保持完好，并从纳米棒延伸到衬底。此外，BCP的少数块被显示为湿了桥接纳米棒的底部。这种桥联状态对未来自组装纳米器件的发展非常有前景。
The self-assembly of gold nanorods (AuNRs) of different sizes with a block copolymer (BCP) is studied. Polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP) films containing P2VP functionalized AuNRs are solvent annealed resulting in a BCP morphology of vertical P2VP cylinders in a PS matrix. At the surface of the PS-b-P2VP films long AuNRs are found in the bridging and vertical states. The bridging state is where the long axis of the AuNR is parallel to the film surface, the AuNR is embedded in the film, and each end of the AuNR is at the top of nearest neighbor P2VP cylinders. The vertical state is where the AuNR is localized within a vertical P2VP cylinder, the AuNR long axis is perpendicular to the film surface and the upper tip of the AuNR is at the film surface. Short AuNRs were found in the bridging and vertical states as well as in a state not observed for the long AuNRs, the centered state. The centered state is where an AuNR has its long axis parallel to the film surface, is embedded in the film, and is centered over a vertical P2VP cylinder. Hybrid particle-field theory (HPFT) simulations modeling the experimental system predict that for the long AuNRs only the bridging state should be observed while for the short AuNRs only the bridging and centered states should be observed. Possible explanations for why the vertical state is observed in experiments despite being thermodynamically unfavorable in simulations are discussed. HPFT simulations also show that when a nanorod is in the bridging state the two cylinders it bridges remain intact and extend from the nanorod to the substrate. Further, the minority block of the BCP is shown to wet the bottom of the bridging nanorod. The bridging state is very promising for the future development of self-assembled nanoscale devices.