Detecting bound polymer layers in attractive polymer–nanoparticle hybrids
Detecting bound polymer layers in attractive polymer–nanoparticle hybrids
复制标题
检测有吸引力的聚合物与纳米颗粒混合物中的结合聚合物层
DOI：
10.1039/d1nr02395k
复制
发表时间：
2021
期刊：
影响因子：
6.7
通讯作者：
Kumar, Sanat K.
中科院分区：
文献类型：
--
作者：
Emamy, Hamed;Starr, Francis W.;Kumar, Sanat K.
当聚合物-纳米颗粒（NP）吸引力足够强时，在NP界面处自发地形成具有不同动态特征的结合聚合物层。对于薄聚合物膜，类似的现象发生在固定的有吸引力的基底附近。虽然我们之前的模拟固定了NP以检查稀释极限，但在这里，我们允许NP移动。我们的目标是研究NP移动性如何影响绑定层的签名。对于相对移动的的小NP，束缚层从属于NP的运动，并且中间散射函数中的束缚层松弛的签名基本上消失。当在NP参考系中测量散射函数时，可以恢复束缚层的缓慢弛豫，但是在具有多个NP的实验系统中实现该过程将是具有挑战性的。相反，我们使用的反直觉的结果，NP质量影响其流动性在纳米级的限制，沿着更预期的结果，结合层增加有效的NP质量，表明结合的聚合物的签名表现为NP扩散率的变化。这些发现使我们能够合理化和定量地了解最近的实验结果，重点是测量NP扩散与物理吸附或化学接枝链。
When polymer–nanoparticle (NP) attractions are sufficiently strong, a bound polymer layer with a distinct dynamic signature spontaneously forms at the NP interface. A similar phenomenon occurs near a fixed attractive substrate for thin polymer films. While our previous simulations fixed the NPs to examine the dilute limit, here, we allow the NP to move. Our goal is to investigate how NP mobility affects the signature of the bound layer. For small NPs that are relatively mobile, the bound layer is slaved to the motion of the NP, and the signature of the bound layer relaxation in the intermediate scattering function essentially disappears. The slow relaxation of the bound layer can be recovered when the scattering function is measured in the NP reference frame, but this process would be challenging to implement in experimental systems with multiple NPs. Instead, we use the counterintuitive result that the NP mass affects its mobility in the nanoscale limit, along with the more expected result that the bound layer increases the effective NP mass, to suggest that the signature of the bound polymer manifests as a change in NP diffusivity. These findings allow us to rationalize and quantitatively understand the results of recent experiments focused on measuring NP diffusivity with either physically adsorbed or chemically end-grafted chains.