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Effect of Neutralization on the Structure and Dynamics of Model Ionomer Melts
Macromolecules ( IF 5.5 ) Pub Date : 2018-01-03 00:00:00 , DOI: 10.1021/acs.macromol.7b02073
Janani Sampath 1 , Lisa M. Hall 1
Affiliation  

Using coarse-grained molecular dynamics simulations, we investigate how ionomer behavior depends on ion and acid content. Our coarse-grained model builds on a prior model that was successful in capturing the low wavevector ionomer peak observed in X-ray scattering. As in prior work, we consider a linear backbone of neutral monomer beads with charged pendant beads and unbound counterions; we now also include “stickers” pendant to the backbone to represent unneutralized acid groups. These stickers are similar to backbone monomers but have higher cohesive interaction strength with each other and with the ionic groups, chosen to approximately match structural features of prior atomistic simulations. This allows us to simulate partially neutralized materials over longer time and length scales than is possible atomistically. We find that stickers can aid in ionic aggregate rearrangements such that samples containing sticker groups can show a lower viscosity than samples with the same ion content but without stickers; this agrees with experimental results of analogous materials.

中文翻译:

中和对模型离聚物熔体结构和动力学的影响

使用粗粒度的分子动力学模拟,我们研究了离聚物行为如何取决于离子和酸含量。我们的粗粒度模型建立在现有模型的基础上,该模型成功捕获了X射线散射中观察到的低波矢离聚物峰。与先前的工作一样,我们考虑中性单体珠的线性骨架,其中带电的侧珠和未结合的抗衡离子;我们现在还在骨架上包括“贴纸”侧链,以代表未中和的酸基团。这些标签类似于主链单体,但彼此之间以及与离子基团具有更高的内聚相互作用强度,其选择为与现有原子模拟的结构特征大致匹配。这使我们能够以比原子方法更长的时间和更长的比例来模拟部分中和的材料。我们发现,不干胶标签可以帮助离子聚合重排,从而使含有不干胶标签基团的样品比具有相同离子含量但不具有不干胶标签的样品具有更低的粘度。这与类似材料的实验结果一致。
更新日期:2018-01-03
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