Structure of Polymer-Grafted Nanoparticle Melts.
Structure of Polymer-Grafted Nanoparticle Melts.
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DOI：
10.1021/acsnano.0c06134
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发表时间：
2020-11-24
期刊：
影响因子：
17.1
通讯作者：
Nikoubashman A
中科院分区：
文献类型：
--
作者：
Midya J;Rubinstein M;Kumar SK;Nikoubashman A
通过粗粒分子动力学模拟研究了聚合物接枝纳米粒子（GNP）的纯熔体结构。我们系统地改变聚合度和接枝密度在固定的NP半径，并详细研究了GNP电晕的形状和大小。对于足够高的接枝密度，靠近NP核的链段延伸并形成干燥层。进一步远离NP，存在互穿层，其中相邻GNP的聚合物冠重叠并且链部分具有几乎未扰动的构象。为了更好地理解这种分区，我们开发了一个两层模型，代表接枝聚合物周围的NP球形干燥和互穿层。该模型定量预测，两层的厚度取决于一个通用参数，x，接枝链相对于链在熔体中的过度拥挤的程度。模拟和理论都表明，在固定的接枝密度下，扩链自由能随链长的增加是非单调的，有一个明确的最大值。这个最大值是指示的交叉从干层为主的互穿层为主的制度，它可能会产生深远的影响，我们的理解这些GNP的各种异常传输特性。因此，我们的理论方法为理解和设计无溶剂GNP基材料提供了一种简便的方法。
The structure of neat melts of polymer-grafted nanoparticles (GNPs) is studied via coarse-grained molecular dynamics simulations. We systematically vary the degree of polymerization and grafting density at fixed NP radius, and study in detail the shape and size of the GNP coronas. For sufficiently high grafting density, chain sections close to the NP core are extended and form a dry layer. Further away from the NP there is an interpenetration layer, where the polymer coronas of neighboring GNPs overlap and the chain sections have almost unperturbed conformations. To better understand this partitioning, we develop a two-layer model, representing the grafted polymer around a NP by spherical dry and interpenetration layers. This model quantitatively predicts that the thicknesses of the two layers depend on one universal parameter, x, the degree of overcrowding of grafted chains relative to chains in the melt. Both simulations and theory show that the chain extension free energy is non-monotonic with increasing chain length at fixed grafting density, with a well defined maximum. This maximum is indicative of the crossover from the dry layer-dominated to interpenetration layer-dominated regime, and it could have profound consequences on our understanding of a variety of anomalous transport properties of these GNPs. Our theoretical approach therefore provides a facile means for understanding and designing solvent-free GNP-based materials.
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影响因子：
41.2
作者：
Akcora, Pinar;Liu, Hongjun;Douglas, Jack F.
通讯作者：
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影响因子：
17.1
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作者：
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