Possible explanation of the Λ-shape anomaly in polymer surface diffusion

被引:19
作者
Mukherji, Debashish [1 ]
Muser, Martin H.
机构
[1] Univ Western Ontario, Dept Appl Math, London, ON N6A 5B7, Canada
[2] Univ Western Ontario, Dept Phys & Astron, London, ON N6A 3K7, Canada
来源
PHYSICAL REVIEW E | 2006年 / 74卷 / 01期
关键词
D O I
10.1103/PhysRevE.74.010601
中图分类号
O35 [流体力学]; O53 [等离子体物理学];
学科分类号
070204 ; 080103 ; 080704 ;
摘要
We suggest an explanation for the anomalous behavior of the polymer surface-diffusion coefficient D reported by Zhao and Granick [J. Am. Chem. Soc. 126, 6242 (2004)]: D first increased with increasing polymer surface concentration Gamma, then suddenly dropped at a threshold value Gamma(*). Our molecular dynamics simulations show the same behavior. We find that polymers form single-layered pancake structures for Gamma <Gamma(*), while double layers form for Gamma >Gamma(*). The double-layer structures allow the polymers to better adapt to the substrate corrugation. This increases barriers for lateral diffusion and is thus consistent with small values of D at larger Gamma.
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页数:4
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