Conformational Properties of Comb-shaped Polyelectrolytes with Negatively Charged Backbone and Neutral Side Chains Studied by a Generic Coarse-grained Bead-and-Spring Model
Conformational Properties of Comb-shaped Polyelectrolytes with Negatively Charged Backbone and Neutral Side Chains Studied by a Generic Coarse-grained Bead-and-Spring Model
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DOI：
10.1007/s10118-020-2350-9
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发表时间：
2019-10-25
影响因子：
4.3
通讯作者：
Ran, Qian-Ping
中科院分区：
文献类型：
--
作者：
Chen, Jian-Hua;Lu, Li-Qun;Ran, Qian-Ping
一个通用的粗粒珠和弹簧模型，映射到梳形聚羧酸酯基（PCE）高效减水剂，开发和研究Langevin分子动力学模拟与隐式溶剂和显式抗衡离子。与实验结果的一致表明，我们的模型可以用于研究溶液中的PCE的平衡尺寸。探讨了离子强度、侧链数目和侧链长度对PCE溶液构象行为的影响。单链平衡性质，包括回转半径，端到端的距离和持久性长度的聚合物主链，形状非球面参数，和平均跨度尺寸，被确定。结果表明，随着离子强度的增加，聚合物的平衡尺寸略有减小，骨架的持久长度与德拜屏蔽长度呈线性关系，这与Dobrynin的理论一致.增加侧链数目和/或侧链长度不仅增加了聚合物整体的平衡尺寸（回转半径和平均跨度），而且由于排除的体积相互作用而增加了主链的持久长度。
A generic coarse-grained bead-and-spring model, mapped onto comb-shaped polycarboxylate-based (PCE) superplasticizers, is developed and studied by Langevin molecular dynamics simulations with implicit solvent and explicit counterions. The agreement on the radius of gyration of the PCEs with experiments shows that our model can be useful in studying the equilibrium sizes of PCEs in solution. The effects of ionic strength, side-chain number, and side-chain length on the conformational behavior of PCEs in solution are explored. Single-chain equilibrium properties, including the radius of gyration, end-to-end distance and persistence length of the polymer backbone, shape-asphericity parameter, and the mean span dimension, are determined. It is found that with the increase of ionic strength, the equilibrium sizes of the polymers decrease only slightly, and a linear dependence of the persistence length of backbone on the Debye screening length is found, in good agreement with the theory developed by Dobrynin. Increasing side-chain numbers and/or side-chain lengths increases not only the equilibrium sizes (radius of gyration and mean span) of the polymer as a whole, but also the persistence length of the backbone due to excluded volume interactions.