Tong Chaohui
Department of Physics, Ningbo University , Ningbo 315211, China.
Langmuir. 2014 Dec 23;30(50):15301-8. doi: 10.1021/la503526a. Epub 2014 Dec 12.
The self-consistent field theory (SCFT) is employed to numerically study the response of weak polybase type polymer chains grafted on a sphere to electric fields generated by the uniform positive or negative charges on the grafting substrate in the planar polyelectrolyte brush limit. Also the effect of curvature of the grafting sphere on the brush height of weak polybase brushes in the absence of surface charges is investigated. The numerical study reveals interesting and nontrivial dependence of the brush height on the radius of the grafting substrate. Consistent with experimental results, in the parameter range of the surface charge density examined, the brush height is found to be independent of the applied electric field at intermediate and high grafting densities. At relatively low grafting density, the applied negative surface charge which is termed as negative bias in this study results in a reduction of the brush height. At rather low grafting density, the positive bias corresponding to applied positive surface charges can lead to a slight increase in the brush height. The underlining mechanism governing the response of weak polybase brushes to the applied electric field is elucidated.
采用自洽场理论（SCFT）对平面聚电解质刷极限下接枝在球体上的弱聚碱型聚合物链对接枝基底上均匀正电荷或负电荷产生的电场的响应进行数值研究。此外，还研究了在无表面电荷情况下接枝球体的曲率对弱聚碱刷高度的影响。数值研究揭示了刷高度对接枝基底半径的有趣且非平凡的依赖性。与实验结果一致，在所研究的表面电荷密度参数范围内，发现在中等和高接枝密度下，刷高度与外加电场无关。在相对较低的接枝密度下，本研究中称为负偏压的外加负表面电荷会导致刷高度降低。在相当低的接枝密度下，对应于外加正表面电荷的正偏压会导致刷高度略有增加。阐明了弱聚碱刷对外加电场响应的潜在机制。
