Friction between Strongly Compressed Polymer Brushes

IF 4.1 2区化学 Q2 POLYMER SCIENCE Chinese Journal of Polymer Science Pub Date : 2024-06-05 DOI:10.1007/s10118-024-3151-3

Qi Liao

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Abstract

We present the results of molecular dynamics simulations of steady shear between a pair of neutral polymer brushes, as well as a pair of charged polymer brushes in the strongly compressed regime. The results of the molecular dynamic simulations of neutral and polyelectrolyte brushes in implicit solvent including normal forces, shear forces, viscosities and friction coefficients as a function of separation between brushes, are presented in the study. The comparison of the simulation results of neutral and charged brushes shows that the charged brushes is in the quasi-neutral regime, and the dependence of viscosity on the separation distance show the similar power law of neutral brushes. Our simulation results confirm that the implicit solvent simulations of polyelectrolyte brushes that ignore hydrodynamics interaction are in agreement with the scaling predictions qualitatively because of screening of hydrodynamic interaction and long-range electrostatic interactions on the correlation length scale. Both of neutral and charged brushes show the lubrication properties that the friction coefficient decreases with the separation decreases at enough large loads. However, a maximum of friction coefficients is observed for polyelectrolyte brushes, which is in contrast to the neutral brushes with monotonical dependence.

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强压缩聚合物刷之间的摩擦力

我们介绍了一对中性聚合物刷和一对带电聚合物刷在强压缩状态下稳定剪切的分子动力学模拟结果。研究中介绍了隐式溶剂中的中性刷和聚电解质刷的分子动力学模拟结果，包括法向力、剪切力、粘度和摩擦系数与刷之间分离度的函数关系。对中性电刷和带电电刷的模拟结果进行比较后发现，带电电刷处于准中性状态，而粘度与分离距离的关系则显示出与中性电刷类似的幂律。我们的模拟结果证实，由于流体动力学相互作用和长程静电相互作用在相关长度尺度上的屏蔽作用，忽略流体动力学相互作用的隐式溶剂模拟聚电解质电刷与缩放预测定性一致。中性电刷和带电电刷都显示出润滑特性，即在足够大的载荷下，摩擦系数随着分离度的减小而减小。然而，聚电解质电刷的摩擦系数达到最大值，这与中性电刷的单调依赖性形成鲜明对比。

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来源期刊

Chinese Journal of Polymer Science 化学-高分子科学

CiteScore

7.10

自引率

11.60%

发文量

218

审稿时长

6.0 months

期刊介绍： Chinese Journal of Polymer Science (CJPS) is a monthly journal published in English and sponsored by the Chinese Chemical Society and the Institute of Chemistry, Chinese Academy of Sciences. CJPS is edited by a distinguished Editorial Board headed by Professor Qi-Feng Zhou and supported by an International Advisory Board in which many famous active polymer scientists all over the world are included. The journal was first published in 1983 under the title Polymer Communications and has the current name since 1985. CJPS is a peer-reviewed journal dedicated to the timely publication of original research ideas and results in the field of polymer science. The issues may carry regular papers, rapid communications and notes as well as feature articles. As a leading polymer journal in China published in English, CJPS reflects the new achievements obtained in various laboratories of China, CJPS also includes papers submitted by scientists of different countries and regions outside of China, reflecting the international nature of the journal.